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29 Blue Dog Breeds Dog Coat Color Genotypes & Genetics Merle, Locus, Liver, Fawn, Fallow, Brindle What Color Will my Puppies Be? Dog Coat Colors and Patterns Blue Dog Color Genetics Dog and Puppy Fur and Nose Colors Variety of Dog Eyes and Coat Colors Extreme Dog Color Schemes What Determines a Dog Coat Color? Do Dogs See in Color? Do Dogs Dream in Color? What does an albino dog look like? Free Dog Coloring Templates Breeding Dogs in Colors Aussie & Brindle Dog Colors White vs Albino Dogs Dog Nose Colors Dog Color Genetics Chart Eumelanin, Pheomelanin & Albinism Dog Coat Colors Chart Dog Eyes Colors Albino Dogs
DOG COLORING & COAT GENETICS The material is proudly presented by
EUMELANIN Does your dog have black fur? Eumelanin is a pigment in a dog's genes that expresses itself in a dog,s coat color, nose color, and eye color. This will determine how "black" a dog's coat is or if they have any black markings on their coat at all. Breeds such as a Black Lab or a Newfoundland dog, for example, will have a strong concentration of Eumelanin in their coats. Do you wonder why most dogs have black noses? This is because the Eumelanin pigment is the default coloration for most dogs! Eumelanin can be altered slightly so that it produces a pigment closer to gray, brown, or light brown. These hues respectively are called "blue," "liver," and "isabella." If a dog's Eumelanin goes more liver, for example, not only will their coat color be affected but also their nose color and eye color.
PHEOMELANIN Does your pup's fur stray more into the red-tones? A secondary pigment called Phaeomelanin is also an important determinant of a dog's fur. Unlike the way that Eumelanin also affects the coloration of a dog's nose and eyes, Phaeomelanin only affects their coat color. Also, Phaeomelanin only expresses one color - red - as opposed to two groups of color like Eumelanin's liver and black. It includes dogs with truly red coats - such as an Irish Setter, and also includes a wider range of hues including golden tans, yellows, and oranges. A dog's genetics determine how pronounced the Phaeomelanin is and how dense the hue of their coat is. Think your dog's coat is totally unique? You are absolutely correct: while families tend to have similar coat patterns, stray spots here and there will differ from dog to dog. This is how every coat color and combination end up being truly unique!
ALBINISM What if your dog's coat is white? Good question: it really doesn't fall under either of the pigments we have explained! White, the presence of all color in the visible light spectrum, is the absence of all color and information in a dog coat. Dogs have white coats whenever both of these pigments are inhibited or whenever the Eumelanin and the Phaeomelanin are extremely weak. For example, whenever a dog has a completely white body and a black nose and darker eyes, it means that the Phaeomelanin is dominant but unpronounced. However, in the case of albino dogs or breeds where the genetics don't clearly delineate a dominant/recessive relationship, the eyes will be blue and the nose will likely be pink because the Eumelanin is not affecting those traits. A true albino dog would have red eyes, but it is more common to find dogs with weakened traits as opposed to the anomaly of actual albinism. "White spotting" under the technical term epistasis, in a dog refers to white patches that lay on top of any Eumelanin or Phaeomelanin on a dog. This means that any dog coat color can be speckled with white regardless of their dominant pigmentation. Like the primary colors on the color wheel, small bits of pigment help determine a wide variety of color. These fundamental principles help us better understand the reasons behind each pup's uniquely colored coat.
B/- D/- E/- K/- = black b/b D/- E/- K/- = brown (chocolate) B/- d/d E/- K/- = blue b/b d/d E/- K/- = fawn ("-" is either the dominant or recessive allele)
AGOUTI: at^at B/- D/- E/- k/k = black with tan points at^at b/b D/- E/- k/k = chocolate with tan points at^at B/- d/d E/- k/k = blue with dilute tan points at^at b/b d/d E/- k/k = fawn with dilute tan points
NON-EXTENSION RED (cream): B/B d/d e/e = dilute red to pale cream with gray nose (dog is genetically a
dilute black, but will be a cream color) B/b d/d e/e = dilute red to pale cream with gray nose (dog is genetically a dilute
black, but will be a cream color) b/b d/d e/e = dilute red to pale cream with rosey-brown nose (dog is genetically
dilute brown, but will be cream color) b/b D/d e/e = dilute red to pale cream with brown nose (dog is genetically
brown, but will be cream color) b/b D/D e/e = dilute red to pale cream with brown nose (dog is genetically
brown, but will be cream color) B/B D/D e/e = dilute red to pale cream with black nose (dog is genetically black,
but will be cream color) B/b D/d e/e = dilute red to pale cream with black nose (dog is genetically black,
but will be cream color)
First of all, please aknowledge and get familiar with the following gene-related definitions:
Gene: Genes control just about everything about a living creature. They control how the creature grows and develops, how it functions and how it looks too. On this site we're focusing on just one aspect of looks - colour.A gene is basically a set of instructions which tells the cell how to produce a particular protein (in our case, pigment). The genetic make-up of a creature is described as its genotype.
Chromosome: The nuclear structure which houses (contains) the genetic information. Chromosomes exist in pairs and therefore there are always two copies of a given gene.
Locus \ Locci: the position of a gene on a chromosome. Every gene has a specific locus. Genes are all tied together into a long strand of DNA. Each point on this strand of DNA is called a locus (locii is the plural). At each locus there are two alleles forming the gene. The alleles present at each locus are picked from a list of possible alleles, which is called a series. There may be any number of alleles in a series, but it's usually 2-5. Each locus has its own series, and the alleles in that series can only occur at that locus. For example, in the E series in dogs there are three alleles - E, Em and e. Each dog has a combination of two of those alleles from the E series on its E locus. It might have one copy of e and one of E, or maybe two copies of Em. See the "Summary of series" page for a list of all the series.
Genotype: the genetic make-up of an individual
Phenotype: While a genotype is the genetic makeup of an organism (a technical list of locii, genes and alleles), phenotype describes the effect of the genotype on the look of the organism. If we talk about a black dog with white markings then we are talking about its phenotype. If we talk about a KkSii dog then we are talking about its genotype.
Homozygous: the condition when both alleles of a gene pair are identical
Heterozygous: the condition when both alleles of a gene pair are different
Dominant: term describing a gene which can produce a phenotype when present only once; also the
Phenotype which results
Recessive: term describing a gene which must be present twice to produce a phenotype; also refers to the phenotype which results
Wild: the "normal" phenotype
Mutant: the non-normal phenotype; is a relative term (relative to the population from which the organism originates
Color Genes: genes that affect the pigment color of hairs
Pattern Genes: genes that affect the distribution of a particular color.
Alleles: Different variants of genes are known as alleles. Alleles come in pairs - one from each parent. When we write about alleles we use letters to denote them, for example a and b.
A true blue friend is one that will loyally stand by your side, and this is the perfect way to describe these blue dog breeds. Each of these canine companions carries the genes for a blue coat color - maybe a light, pale blue or a deeper, steely shade of blue.
Regardless of what shade it takes, all blue-colored dogs are displaying a coat that is in reality influenced by a gene for either a diluted black coat. There are both large and small blue dog breeds. Some of these breeds are recognized within their breed standard as carrying the gene for a blue coat, while others manifest a blue coat that falls outside of the guidelines for the breed. Regardless, many of these blue dog breeds are sought after and highly prized for their good looks and unique blue coat!
There are four types of blue coats, depending on the pattern and whether or not the dog is born blue. They are all inherited differently.
TYPES OF BLUE DOG COATS
1. Blue (dilute): a genetically black or dark brown coat becomes metallic blue-gray in appearance - blue Great Dane, blue Weimaraner. Always with a grey nose or paw pads.
2. Blue (progressive silvering): Puppies are born black, but become blue-gray in adulthood - Kerry blue terrier. Other breeds in which progressive blue can be found: Puli, Havanese, Briard, Poodle and other breeds. Always with a black nose.
3. Blue-tick: Black roaning on white. The blue coloring results from a black / white mottling which gives the impression of a navy blue color. Always with a black nose, e.g. Petit Blue de Gascogne, Blue Belton.
4. Blue Merle: This is a color pattern, more than a color, which looks like marbled gray on black as in the Catahoula leopard dog and the Australian Shepherd dog. Always with a black nose, sometimes blue eyes.
THE GENETICS The dog's coat color is determined by a substance called melanin. There are two distinct types of melanin in the dog, eumelanin and phaeomelanin. Eumelanin will, in the absence of other modifying genes, give the color black or dark brown. Phaeomelanin is, in its unmodified form, red/yellow. In some dogs the coat color dilution can be accompanied by hair loss and recurrent skin inflammation, the so called color dilution alopecia (CDA) or black hair follicular dysplasia (BHFD). Dogs with coat color dilution show a characteristic pigmentation phenotype. The coat colors are lighter in shade, diluted black (eumelanin dilution) giving a silvery grey (blue) and red / yellow giving a cream color - Isabella fawn, also referred to as lilac in some breeds. Note that dark phaeomelanin can ressemble lighter forms of eumelanin and both dark phaeomelanin and brown eumelanin are likely to be considered "red" by many breeders, which only adds to the confusion.
In some breeds blue dilute is termed grey or silver, which further adds to the confusion. This is the case, for example, in the Tervueren, where a dog with diluted red hairs appearing as blue, is usually called grey. In some dog breeds the blue color variety is associated with a specific coat texture. That is the case for example in the Thai ridgeback, where the blue color is almost always associated with a velvet coat texture, while the other colored Thai ridgebacks are can have either a short, a velvet or a long coat.
Blue dilution can sometimes be associated with health issues. An affection called CDA (Color Dilution Alopecia), formerly known as Blue Balding Syndrome or Blue Doberman Syndrome, causes the melanin in the hairshaft to clump together making the hair weak and breakable. Despite its former name this affection is not limited to Dobermans, but can occur in many breeds, most notable are blue Chow Chows, Dachshunds, Whippets, Standard Poodles, and Great Danes. Though fawn (dilute brown) dogs also tend to suffer from the same affection, CDA seems less common in fawns than in blues. Dilute coats also tend to be sparser in general than non-dilutes, with fewer hairs to the inch. In collies there is another type of dilution (Grey collie syndrome) causing acyclic neutropenia, a disorder of the immune system, which renders them defenseless against infection. Puppies with this affection die within a few weeks unless kept on stringent regimens of antibiotics their whole lives.
BLUE DOG BREEDS
1. Australian Cattle Dog Also known as the blue heeler, it's no surprise that the Australian Cattle dog lands on the list of best blue dog breeds. While a red coat is also possible - known as the red heeler, a blue coat on this dog may be solid, mottled, or speckled according to the breed standard. Other markings in black or tan may be present, but the overall impression of a blue heeler is well, blue. Height: 17 to 20 inches, Weight: 35 to 50 pounds. Physical Characteristics: An athletic, muscular and broad dog, smooth, hard double-coat, coat color is usually blue, blue mottled or blue speckled but may also be red.
2. Kerry Blue Terrier As the name suggests, the Kerry blue terrier only comes in one color: blue. This breed has a unique, curly coat that ranges in shade from a deep slate to a light blue gray. While the muzzle, head, ears, tail, and feet may be darker or even black, the breed standard calls for a dog that is described as either "blue gray" or "gray blue," with either color showing more dominantly. However, the blue hue should not be missing. The most interesting thing about this blue dog breed is the fact that puppies are born black. Through a process described as "clearing," the coat of a Kerry blue terrier gradually changes to the characteristic blue coat color. Generally, a dog will have it is mature coat by the age of 18 months. Height: 17 to 19 inches, Weight: 30 to 40 pounds. Physical Characteristics: Medium-size breed with a short coat of curls that is soft and wavy with no undercoat, a bearded face with heavy eyebrows often conceal this breed's eyes.
3. Weimaraner Weimaraners typically are known by their steely gray coat that is actually the dilute of the gene for a brown coat, but in some dogs a black dilute gene is present instead. This produces a dark grey colored dog, often described as a blue Weimaraner. According to the breed standard, this coat color is a disqualified, but regardless, people in search of blue dog breeds are often drawn to the athletic and striking look of the blue Weimaraner. Height: 23 to 27 inches, Weight: 55 to 90 pounds. Physical Characteristics: Sleek body, short coat, blue to gray color.
4. Chihuahua One of the smallest dog breeds, there is no shortage of coat colors for the Chihuahua - including a beautiful blue coat. The gene responsible for producing this rare coat color is recessive, so this is not a common blue dog breed. When it does appear, the blue may be solid, or it can appear in combination with tan, white, fawn, or brown markings. Both long-haired and short-haired chihuahuas may have a blue coat color. Height: 5 to 8 inches, Weight: Up to 6 pounds. Physical Characteristics: Prominent ears and alert expression, short or long coat in many different colors, including black, white, fawn, blue and more. Height: 20 to 22 inches, Weight: 45 to 55 pounds. Physical Characteristics: Medium-sized breed with a distinctive shaggy look, long, coarse topcoat; colors include white with red, brown or brindle markings.
5. Bearded Collie The shaggy coat of the bearded collie comes in a handful colors, including blue. Commonly seen with white markings on the face, chest, legs, and tail, the body is always solid in color from the shoulders back. Blue bearded collies may be born with a darker color coat-blue or grey and gradually lighten as they mature.
6. Boston Terrier The Boston terrier wears a little tuxedo, and while his coat is usually black-and-white in color, a red or blue coat is possible too! Like some other blue dog breeds, the blue coat color is not recognized in the AKC breed standard for Boston Terriers. Regardless, however, this recessive gene does sometimes appear. The blue coat of a Boston terrier may appear distinctly blue in color, or have a silver or grey shade. Height: 15 to 17 inches, Weight: 12 to 25 pounds. Physical Characteristics: Compact but sturdy build with round face and upright ears, smooth coat in solid colors or accented with white.
7. Italian Greyhound The long legs and petite body of the Italian greyhound give this dog a graceful look, especially when it happens to be sporting a blue coat. While not exclusively a blue dog breed, the Italia greyhound does carry the gene for a dilute black coat, which manifests itself as a dark grey with a distinctly blue cast. Height: 13 to 15 inches, Weight: 7 to 14 pounds. Physical Characteristics: Dainty body with deep chest and long legs, thin tail, short, smooth coat in variety of colors including black, blue, fawn, and more.
8. Blue Lacy The Blue Lacy is a rare blue dog breed, originating in the United States in the middle 1800's as a rancher's right-hand companion. While not yet AKC-recognized, the Blue Lacy is the state dog of Texas. These dogs carry the recessive gene responsible for producing a blue coat, but they may also produce puppies that are red, cream, or tricolor. Regardless of coat color, the Blue Lacy is known for having a natural aptitude for work and a high level of intelligence. Height: 18 to 21 inches, Weight: 25 to 50 pounds. Physical Characteristics: Elongated muzzle with folded ears and athletic body type, short and smooth coat in various shades of blue, such as gray, light silver, or deeper charcoal but may also be red or tricolored.
9. Neapolitan Mastiff For a BIG blue dog breed, look no further than the Neapolitan mastiff. This large breed is recognized by its imposing frame and loose skin, which often wrinkles around the head. A blue coat is relatively common, along with black, mahogany, and tawny coat colors. No matter what color coat they have, these dogs are large and in charge! Height: 24 to 31 inches, Weight: 110 to 150 pounds. Physical Characteristics: Large, heavy boned dog with an abundance of loose skin across the body, short coat that comes in black, blue, mahogany, and tawny colors.
10. Chinese Shar-Pei Most people know the Shar-Pei for their folds of skin and wrinkled appearance. However, you may not realize that this dog breed carries the capacity for a variety of coat colors, including blue. The breed standard allows for a Shar-Pei coat to be any color as long as it is solid. Blue Shar-Peis can range from a lighter hue of grey blue to a deeper slate color. Some of these dogs have shading along the back and ears, but it must be of the same color as the rest of the coat. Interestingly, this blue dog breed has a blue-black tongue, regardless of coat color! Height: 18 to 20 inches, Weight: 45 to 60 pounds. Physical Characteristics: Compact, medium-sized dog known for distinctive appearance; wrinkled faces with loose skin, a blue-black tongue, small, round eyes, and very small, triangular ears, coats are very short and bristly, coming in black, brown, cream, and blue.
11. Irish Wolfhound The gene responsible for diluting a black coat into a blue one is present in Irish wolfhounds as well. It is believed that this trait was inherited from another blue dog breed, the Great Dane. While many blue Irish wolfhounds may appear somewhat gray at first glance, those with a blue coat have a distinctive blue tint to their coat and might also have liver-colored paw pads, nose, and eye rims. Height: 30 inches and up, Weight: 105 to 120 pounds. Physical Characteristics: Tall, long body, rough coat, colors include black, blue, brindle, cream, gray, and more.
12. American Staffordshire Terrier The American Staffordshire terrier is a breed of many colors, but is included on the list of blue dog breeds for its steel grey coat that often is described as blue. It generally appears in combination with white patches. Regardless of coat color, these dogs have short, coarse hair. Height: 17 to 19 inches at the shoulder, Weight: 40 to 70 pounds. Physical Characteristics: Medium to large dog with a muscular build and square head, short, smooth coat in many different colors.
13. Thai Ridgeback The Thai Ridgeback traces its history to the mid-17th century in eastern Thailand. Given the relative isolation of eastern Thailand and primitive transportation options, limited cross breeding allowed the Thai Ridgeback to remain pure for centuries. This hunting dog and watchdog is still little known outside Thailand. The Thai Ridgeback name refers to the ridge line of hair growing in the opposite direction of the main coat - creating a ridge, or crest, behind the ears. This muscular large breed has a natural hunting instinct and must be well trained at an early age. The Thai Ridgeback was an independent breed and most likely survived on the spoils of the hunt and small barn animals. This would have been nutritionally insufficient should the Thai Ridgeback been suffering from sensitive stomach issues.
14. Great Dane Blue Great Dane puppy's coat color is a standard Great Dane breed color. The blue puppy Danes are favored generally and would develop into dog show acceptable dogs. They are also regarded as a tainted variant of a black Great Dane coat color. Both these coat colors are revered as standard Great Dane coat colors. The Blue Great Danes are standard Danes. As, the Blue Great Dane puppy is born with the recessive blue gene in its genetic makeup. Transforming the coat color of a Black Dane into its dilute coat bearing Blue color. A Blue Great Dane puppy require particular feed and exercise alike Great Dane dogs. This beautiful coat colored dog is joyful, faithful, appeasing, and friendly indeed.
15. Chow Chow The blue Chow Chow is one of the most ancient dog breeds on Earth and also one of the noblest. Even today, to see a blue Chow Chow walk past is like watching history itself walk by. With this dog's lion-like head ruff and dignified bearing, there is no mistaking a Chow Chow when you meet one!
16. Bedlington Terrier The Bedlington Terrier is a breed of small dog named after the mining town of Bedlington, Northumberland in North East England. Originally bred to hunt vermin the Bedlington Terrier has since been used in dog racing, numerous dog sports, as well as in conformation shows and as a companion dog.
17. Doberman Most of us are familiar with the Doberman dog breed - the attractive black and tan dogs known for making great guardians. But not many of us may be familiar with the blue doberman, a color variation of this breed. No, these dogs are not blue in the real sense of the word, so don't imagine them as being Smurf blue or electric blue. The word blue in this case refers to the dilution of the black coat color, which gives these dogs an attractive grayish hue that draws the attention of many people in search of an unusual looking Doberman. Dobermans are known to come in several coat colors. The American Kennel Club lists four coat colors for this breed: black and rust, blue and rust, fawn (isabella) and rust, and red and rust. The rust markings are typically found above each eye, on the muzzle, throat and fore chest, on all legs and feet, and below the tail. While Dobermans can also come in a white color, this coat color is not accepted as standard.
18. Glen of Imaal Terrier Glens are scruffy, sturdy, low-slung terriers standing no more than 14 inches at the shoulder. There is nothing fancy or fussed-over about Glens. Rather, their wiry no-frills coat, broad head, and bowed front legs suggest a working farm dog from a time and place where substance was more important than style. And yet, they are also ridiculously cute. It takes a heart of stone to resist reaching down to give a Glen a scratch behind the ear and a pat on the well-muscled rump. Height: 12.5-14 inches, Weight: 32-40 pounds.
19. Havanese Distinctive features of the Havanese include a curled-over tail and a gorgeous silky coat, which comes in a variety of colors. Some owners enjoy cording the coat, in the manner of a Puli, and others clip it short to reduce grooming time. Happily, Havenese are just as cute no matter what hairdo you give them. Their small but sturdy bodies, adaptable nature, and social skills make Havanese an ideal city dog, but they are content to be anywhere that they can command the attention of admirers young and old alike. Havanese, smart and trainable extroverts with the comic instincts of a born clown, are natural trick dogs. Havanese are also excellent watchdogs and take the job seriously, but will usually keep the barking to a minimum. Height: 8.5-11.5 inches, Weight: 7-13 pounds.
20. Lakeland Terrier A bold, zesty "big dog in a small package," the Lakeland Terrier, named for the Lake District of his native England, was once a farmer's dog bred to work in packs on sheep-stealing foxes. The Lakeland's coat is hard, wiry, and low-shedding. Square and sturdy Lakelands, standing less than 15 inches at the shoulder and weighing about 17 pounds, are small dogs. But don't tell them that. With their cock of the walk swagger, Lakelands personify the old dog-lover's cliche "a big dog in a small package." They come in several colors, some have a sporty saddle mark on the back. With folded V-shaped ears, straight front, rectangular head, and a mischievous twinkle in their eye, Lakelands are the blueprint of a long-legged British terrier. Height: 14-15 inches (male), slightly smaller (female), Weight: 17 pounds (male), slightly smaller (female).
21. Old English Sheepdog The Old English Sheepdog is the archetypical shaggy dog, famous for his profuse coat and peak-a-boo hair, a distinctive bear-like gait, and a mellow, agreeable nature. The OES is a big, agile dog who enjoys exploring and a good romp. Beneath the Old English Sheepdog's profuse double coat is a muscular and compact drover, with plenty of bone and a big rump, standing 21 or 22 inches at the shoulder. Their eyes, when you can see them, are dark brown, or blue, or one of each. The OES breed standard says the skull is capacious and rather squarely formed, giving plenty of room for brain power. OES move with a bear-like shuffle but are famous for their nimbleness afoot. Regular exercise is required for these strong, able-bodied workers. Equally famed are their many fine housedog qualities: watchfulness, courage, kindliness, and intelligence. Great with children, OES make patient, protective playmates. They are sensible watchdogs known for a loud, ringing bark. Height: 22 inches & up (male), 21 inches & up (female), Weight: 60-100 pounds.
22. Plott Hound The Plott Hound, a hound with a curious name and a unique history, is a rugged, relentless hunting dog who is a mellow gentleman at home but fearless, implacable, and bold at work. This eye-catching scenthound is North Carolina's state dog. The hound with the curious name and unique history is a streamlined, long-tailed, light-footed hunter standing as high as 25 inches at the shoulder. The flashy coat comes in an array of brindle-stripe patterns, from black flecked with gold to flaming orange and russet, in addition to some solid colors. The medium-length ears hang gracefully, and the leather of the nose, lips, and eye rims are black, setting off an inquisitive and confident expression. Height: 20-25 inches (male), 20-23 inches (female), Weight: 50-60 pounds (male), 40-55 pounds (female).
23. Pomeranian The tiny Pomeranian, long a favorite of royals and commoners alike, has been called the ideal companion. The glorious coat, smiling, foxy face, and vivacious personality have helped make the Pom one of the world's most popular toy breeds, The Pomeranian combines a tiny body (no more than seven pounds) and a commanding big-dog demeanor. The abundant double coat, with its frill extending over the chest and shoulders, comes in almost two dozen colors, and various patterns and markings, but is most commonly seen in orange or red. Alert and intelligent, Pomeranians are easily trained and make fine watchdogs and perky pets for families with children old enough to know the difference between a toy dog and a toy. Poms are active but can be exercised with indoor play and short walks, so they are content in both the city and suburbs. They will master tricks and games with ease, though their favorite activity is providing laughs and companionship to their special human.
24. Pyrenean Sheepdog Enthusiastic, mischievous, and whip-smart, the Pyrenean Shepherd is an indefatigable herder descended from ancient sheepdogs of the Pyrenees mountains. Tough and sinewy Pyr Sheps come in "rough-faced" and "smooth-faced" coat varieties. These tough, lean, and lively herders, famous for their vigorous and free-flowing movement, come in two coat varieties: rough-faced and smooth-faced. Roughs have profuse, "windswept" hair above the muzzle and a generally harsh coat, smooths have short facial hair, a finer-textured coat, and a slightly longer, pointier muzzle. Both varieties of this sinewy, rectangular breed come in many colors and patterns. Pyr Sheps see the world through dark almond-shaped eyes conveying an alert and cunning expression. Height: 15.5-18.5 inches (male rough-faced), 15-18 inches (female rough-faced), 15.5-21 inches (male smooth-faced), 15.5-20.5 inches (female smooth-faced), Weight: 15-30 pounds.
25. Bluetick Coonhound The sleekly beautiful Bluetick Coonhound is a sweet and affectionate charmer who might enjoy snoozing in the shade, but in pursuit of quarry he is relentless, bold, and single-minded. His off the charts prey drive must be channeled. Blueticks are speedy and compact nocturnal hunters named for the mottled or "ticked" black-and-blue pattern of the glossy coat. A large male can top out at 27 inches and 80 pounds, females are smaller. Blueticks are well-muscled but sleek and racy, never chunky or clumsy. The baying, bawling, and chopping bark of Blueticks might be cacophonous to some, but to coon hunters it's the music of the night. The droopy-eared charm of Blueticks is irresistible. They crave affection and are deeply devoted to those who provide it. Blueticks have tremendous prey drive. Neglected, underemployed coonhounds with no outlet for their hardwired impulses can develop problem behaviors, like serenading the neighbors with loud, mournful "music."
26. Grand Blue de Gascogne The Grand Bleu de Gascogne is a breed of dog of the scenthound type, originating in France and used for hunting in packs. Today's breed is the descendant of a very old type of large hunting dog, and is an important breed in the ancestry of many other hounds. The Grand Bleu de Gascogne is one of the original bloodhound breeds in Europe. In the Middle Ages, noblemen often kept a pack of these fine dogs to use in their favourite pursuit, hunting. Their melodious howls would often be heard as they chased deer and other large game through the countryside. However, the breed lost much of its popularity in France between the 18th and 20th centuries. Instead, the mantle of preserving the breed fell to the United States where they had been exported to French colonies. Here the breed successfully managed to make it into the modern age. Grand Bleu are extremely active dogs who are still most suited to a working environment or at least a rural setting. They are pack animals who would prefer to spend as much time as possible with their families. Any alone time will probably be spent practising their howling. However, with the right amount of exercise and companionship, a Grand Bleu will prove to be a friendly hunting companion who is always ready to follow a scent and set off on another adventure. Height: Male: 65-72 cm, Female: 62-68 cm, Weight: Male: 35-39 kg, Female: 35-39 kg.
27. Petit Blue de Gascogne The dark brown eyes, slate blue coat and pendulous ears of the Petit Bleu de Gascogne will be very familiar to any fans of the original Grand Bleu de Gascogne dog. Indeed, the two share many physical and character traits, differing only by their size and the prey that they are best suited to hunt. The Petit Bleu de Gascogne breed was deliberately bred by those French hunters who wanted to hunt rabbits and hares rather than boar and deer. Though commonly kept as a pet nowadays, the Petit Bleu de Gascogne retains its hunting instincts and still has superb scenting abilities and the endurance to track for miles. Despite this, they can make wonderful and affectionate family members, as long as their owner dedicates plenty of time to keeping them entertained and are strict with their training.
28. Petit Griffon de Gascogne The Griffon Bleu de Gascogne, Is a breed of dog of the scenthound type, originating in France, and is a versatile hunting dog, used on small and large game, in packs or individually. The Griffon Bleu de Gascogne has a speckled, rough coat. The Griffon Bleu de Gascogne is descended from crosses between the Bleu de Gascogne and the Griffon Nivernais, and possibly the Grand Griffon Vendeen as well. The breed declined for many years, but is now experiencing a revival. The breed has a good nose and a good voice, and is a good and very alert hunting dog for all kinds of hunting, not just as a pack hound for large game. Examples of the Griffon Bleu de Gascogne have been exported to other countries, where they are promoted as a rare breed for those seeking a unique pet. The Griffon Bleu de Gascogne is a medium-large dog, 50 to 57 cm (10.5-22.4 ins) at the withers, with a distinctive rough (shaggy) blue speckled coat, drop ears that are not as long as those on other hounds, and a tail carried up and in a slight curve.
29. Basset Blue de Gascogne Often confused with its cousin, the Basset Hound, the Basset Bleu de Gascogne is a much rarer breed, with only a handful being registered by the Kennel Club. Like the Basset Hound, it originated in France as a slow-and-steady type of hunting dog with which hunters could keep pace on foot. True to its origin, today's Basset Bleu retains a strong prey drive and an incredible sense of smell, with which it can track scent trails that are several days old. As a working dog, it is generally kept in packs, and it is extremely sociable and easy-going with other dogs. It develops a strong bond with its owners, and makes a playful and good-natured pet for people of all ages. While it is not built for speed, it does need a good deal of exercise, and is an ideal walking or hiking companion for active owners. Like many hounds, the Basset Bleu de Gascogne has a musical voice that it is fond of using, which can create tensions with neighbours in urban areas, especially if the dog is left alone for periods during the day. Its coat is easy to care for, but it sheds steadily throughout the year, and often has a strong "doggy" odour that some owners may find off-putting. It is generally a healthy breed, but prospective owners do need to do their research before buying a pup, especially given that there are currently no UK-registered breeders, and so the few dogs that are imported each year are often not viewed in the flesh before being bought. The average life expectancy for the breed is 12 to 14 years.
ALBINISM IN DOGS This article proudly presented by WWW.DOGICA.COM and WWW.PETCARERX.COM
There are two main types of albinism: Oculocutaneous - eyes, skin, and hair. Ocular - just eyes.
There are also different levels of albinism, and different types within those two classifications. In fact, until recently, a lot of people denied they even existed. Sure, white dogs are everywhere!
But albino dogs aren't just white - they a complete or almost complete lack of pigment in the fur, skin, eyes, and nose. True albino dogs with no pigment at all are extremely rare.
In 1976, a white female Doberman Pinscher named Padula's Queen Shebah was born to two black and rust parents. Shebah was bred to her son to produce more white Dobermans. Since then, several thousand Dobermans, many of them white, have descended from Shebah. Although they are called white, they are actually light cream, with blue eyes and pink nose, lips and eye rims. The Doberman Pinscher Club of America (DPCA), backed by several geneticists, contended they were albinos. But many of their breeders insisted they weren't because they didn't fit the image of the prototypical albino with white fur and pink eyes.
Dobermans are the only breed in which albinos appear to be purposefully bred, very much against the wishes of the DPCA. They squint in bright light, and they're prone to sunburn, which may lead to skin tumors. A recent study (Winkler PA, Gornik KR, Ramsey DT, Dubielzig RR, Venta PJ, et al. (2014) found albino Dobes had a much higher incidence of eye and skin melanocytic tumors than normally pigmented Dobes.
What Causes Albinism? A completely pure white animal with pink eyes and pale pink skin is considered albino, and is technically referred to as tyrosinase-negative. Tyrosinase is an enzyme involved in melanin production, and melanin is the natural substance that gives color (or pigment) to the eyes, skin, and hair. Albinism is a lack or defect of this enzyme and is caused by a recessive gene that is inherited from both parents. Many true albino dogs will suffer from deafness because the unpigmented skin in the ear canal causes the nerve endings to degenerate.
The truth is, more than 60 different gene mutations in various species are known to cause albinism, often with slightly different effects. Light fur with blue eyes is typical of the most common type of albinism, oculocutaneous albinism type 2 (OCA2), in humans. It is now acknowledged that white Dobermans are in fact albinos, and the causative gene has recently been discovered.
The mutation is not a part of any of the known dog color loci. This includes the C series, where mutations causing albinism in many others species, including cats, rats and mice, have been identified. However, mutations in SLC45A2 cause the OCA4 type of albinism responsible for cream-colored Bengal tigers, horses, and gorillas, as well as some albino humans.
But Dobes are not the only breed with albinos. Pekingese seem to have the second largest number, but they have also been seen in Shih Tzu, Poodles, Pit Bulls, Beagles, Pugs, Dachshunds and doubtless, many others. In the few individuals tested, they don't seem to share the same mutant gene with the albino Dobes, nor do they seem to share the C-series allele seen in so many other domestic albino animals. In no breed is the purposeful breeding of these dogs encouraged. Nonetheless, if you have one, they make fine companions but you need to take steps to keep them from being dazzled by bright light or from getting sunburned.
Despite the fact that albinism is equally rare among all vertebrates from humans to fish and birds, the real albino dogs are even rarer due to two reasons. The first reason is that the most "albino" dogs pictures on the internet depicting pretty normal dogs with white fur. The second one, it's a bit hard to figure out if your dog is real albino.
Tip #1 - Inspect the dog's coat. If the dog is predominantly white, but has some brown or black fur around the nose or feet, the dog is not an albino. The albino dog is unable to produce hair color of any kind.
Tip #2 - Spread the fur and look at the dog's skin. Many dogs have mottled skin with large colored patches beneath their fur. These are normal skin colorations and prove that the dog has the ability to produce melanin, the key component in skin coloration. Albinos lack the ability to produce melanin.
Tip #3 - Look at the dog's eyes. If the iris of the eyes is brown, the dog has normal melanin distribution. If the iris of the eyes is pink, the dog is an albino. The iris appears pink because the eyes lack the pigment to shelter the blood vessels of the eye.
Albinism is rare in all animals, including dogs, and many people easily confuse white-coated dogs, or dogs that exhibit forms of albinism, for albinos. True albinism is a genetic condition in which pigmentation of eyes, coat, and skin is completely absent. An important distinction to draw between dogs with white coats and albino dogs is that white-coated dogs produce the color white, while albinos only appear white due to lack of pigmentation.
All-white dogs have genetic markers by virtue of which the white pigment masks, or suppresses, all other colors. Albinism, on the other hand, is caused by the absence of both melanin and the enzymes that produce it. That said, some dogs exhibit characteristics of albinism without being true albinos. Let's explore the distinctions, as plainly and legibly as possible, and see what makes an albino dog an albino.
Partial albinism in dogs Some dogs may appear to be true albinos, but retain some pigmentation, which will be most noticeable on the nose or stomach. We can call this partial albinism, but there is actually a range of melanins, and as such, a wide variety of albinisms are possible and observable in dogs. Eyes and skin of albino dogs may appear pink, but it is the diffused color of blood vessels:
In cases of partial albinism, dogs produce only a small amount of melanin, sufficient to produce limited coloration. With the exception of small areas of pigmentation, whether in eyes, skin, or coat, what remains will retain that extremely pale, color-drained appearance.
Coat patterns confused with albinism Instances of limited coloration in non-albino dogs produces two coat patterns, each producing limited color swatches on a dog's coat and skin. These patterns are known in breed standards and kennel clubs as "piebald" and "merle." Piebald dogs have mostly white-colored coats that display large spots or patches of dark coloration. Merle-coated dogs exhibit splotches or patches of color, not only on the coat, but on the skin as well.
Dogs with merle coats are also prone to having heterochromatic, or different-colored, eyes. As in white cats, the genes responsible for coat color, eye, and ear health are not causally linked, so white and albino dogs are not necessarily more likely to be born blind or deaf. However, a rare genetic combination, known as "double merle", does carry inherent health risks. Double merle dogs, like Keller in the photo above, may be mistaken for albino dogs. Unlike true albino dogs, who, aside from light sensitivity, are generally healthy, double-merle-coated dogs are at higher risk for both deafness and blindness. This beautiful dog is Keller, a double merle Australian Shepherd. Her owner writes very movingly about the difficulties and health issues of double merle dogs, not to be confused with albinos:
Light sensitivity in albino dogs Melanin serves a number of uses in the body aside from providing pigmentation. In the eyes, the presence of melanin is one thing that allows dogs to process and filter light. For a true albino dog, without melanin or without much, direct sunlight causes pain in their eyes which makes them squint. True albino dogs should get minimal and carefully managed exposure to direct sunlight.
Light filtration is not the only purpose for melanin. With regard to the skin and body, it provides natural protection from the sun, as well as contributing to the body's ability to fight off infection. Further, albino dogs are far more prone to sunburn and to developing skin cancers due to their extreme photosensitivity.
CONTENTS OF LOCUSes The material is proudly presented by
A locus ("agouti series", affects distribution of both eumelanin and phaeomelanin)
- Ay: Sable (red with or without black tipping). Used to be labelled ay when dominant black was believed to be above it on the A locus, but now black has been given its own locus (K) and sable has been promoted to the most dominant on its locus (so has gained a capital letter!). - aw: Agouti (banded hairs). Like sable above, but the hairs all over are banded with black. This is most likely the gene responsible for wolf grey. - at: Tan points (black body with red on muzzle, chest, eyebrows, legs and vent). Only dominant over recessive black (below), so a dog needs to be homozygous for tan points in order to express them (or heterozygous for recessive black and tan points, but recessive black is very rare). - a - Recessive black (solid black with no red in the coat at all).
B locus ("liver series", affects colour of eumelanin)
- B: Normal pigment. A Bb or BB dog produces normal black eumelanin. - b: Liver pigment. A bb dog produces liver eumelanin instead of black.
D locus ("dilution series", affects intensity of eumelanin)
- D: Normal pigment. - d: Diluted pigment. When homozygous (dd), turns black to blue and liver to isabella.
Breeds Carrying Dilution American Staffordshire Terrier Great Dane Pomeranian Beagle Greyhound Rat Terrier Bearded Collie Harrier Russian Toy Terrier Border Collie Italian Greyhound Schipperke Borzoi Kelpie Shar Pei Canary Dog (Presa Canario) Miniature Pinscher Shih Tzu Cane Corso Mudi Slovakian Pointer Chesapeake Bay Retriever Neapolitan Mastiff Staffordshire Bull Terrier Chihuahua Newfoundland Thai Ridgeback Chow Chow Otterhound Tibetan Mastiff Dobermann Peruvian Inca Orchid Weimaraner Finnish Lapphund Plott Hound Whippet Foxhound (American and English) Podengo Portugueso Xoloitzcuintle German Pinscher
E locus ("extension series", affects distribution of eumelanin)
Grizzle & Domino
- Em: Masked (black on the muzzle and the ears, and sometimes spreading to black tipping on the chest and/or back). - E: Normal extension (no restriction of pigment). Usually written with a capital letter, but is in fact recessive to Em. - Eg: Grizzle/domino (found only in Salukis and Afghan Hounds) - e: Recessive red (solid red all over, except for white markings). An ee dog is unable to produce any eumelanin (black) in its coat. Any black present will be turned to red. The eyes and nose are, however, unaffected (a recessive red dog may still have a black nose).
G locus ("greying series", affects how eumelanin keeps its itensity over time)
- G: Progressive greying. A dog with one or two G genes will be born dark-coloured and its hair will lighten over time. - g: Normal (no lightening of pigment).
Breeds Carrying Greying Gene Old English Sheepdog Bearded Collie Tibetan Terrier Polish Lowland Sheepdog Bedlington Terrier Dandie Dinmont Terrier Basset Griffon Vendeen (Grand and Petit) Poodle (Standard, Miniature and Toy) Irish Wolfhound Deerhound Cesky Terrier Kerry Blue Terrier Havanese Glen of Imaal Terrier
H locus ("harlequin series", modifies merle)
Typical harlequin (HhMm)
Harlequin with the dilution gene, turning the patches and nose blue (ddHhMm)
Harlequin with the sable and masking genes (AyAyEmEmHhMm)
Harlequin with the brindle gene (sable is also necessary for the brindle to show all over the body) (ayaykbrkbrHhMm). The brindle will be broken up and patchy because of the merle gene.
Harlequin with irish spotting (HhMmsisi). The red line shows the border between the harlequin markings and the white spotting.
Merle without the harlequin gene (hhMm)
Lightly-marked harlequin, most likely a double merle (HhMM)
- H: Harlequin. Areas between patches on a merle dog are turned to white, leaving solid pigmented patches on a white base. Only works with merle gene and does not affect non-merle dogs.
- h: Non-harlequin (normal expression of merle).
I locus ("Intensity series", affects the richness of phaeomelanin)
Dilution of phaeomelanin in dogs is now thought to be due to the Intensity locus. Currently, it is not known how this locus works or which alleles are present on it. However, the general idea is that is causes the phaeomelanin in the coat to lighten or darken. The above photos show the range of phaeomelanin colour in recessive red and sable dogs. The I locus does not affect eumelanin in any way, and so doesn't affect the nose or the eyes. The "dudley" noses and unpigmented eye rims sometimes seen in dogs with light-coloured phaeomelanin are in fact generally due to the recessive red gene and not the phaeomelanin dilution itself.
- alleles not yet known
K locus ("black series", "Brindle" affects eumelanin)
Variations In Base Color
The base colour on a brindle can vary as much as red can usually vary, from a deep Irish Setter colour to a light cream. A light base coat on a brindle is generally due to the Intensity locus, which dilutes phaeomelanin (red pigment) to cream, but has no effect on eumelanin (black pigment). These are all details taken from photographs of brindles with black stripes.
Brindle with a Mask
A dog which has at least one Em gene on its E locus will have a black mask. This is an area of eumelanin covering the muzzle and sometimes the ears. If a dog is a brindled sable (brindle gene + sable gene), it'll be brindle all over, and on dogs like this masks may be visible. You may notice that on the Great Dane above the phaeomelanin (red) is deeper on the back and on the chest and legs is almost white. This is most likely due to the urajiro pattern (see the C and I locus page). As urajiro only affects phaeomelanin, the black stripes are unaffected.
Sometimes a brindle dog with black pigment may have silver stripes, usually on a cream background (never deep red). This colouration is generally associated with sighthounds, particularly Afghan Hounds. The overall effect may be similar to how a blue brindle (dd dilution gene) would look. Silver brindle is caused by the greying gene (G locus), which turns black to grey as the dog ages. Sometimes dogs with black stripes and a very light cream base are also referred to as silver brindles.
Brindle and Long Fur
Long and wirey fur can obscure brindle markings by making the stripes less distinct. Even between longhaired breeds, the visibility of brindle can vary. The Dachshund here has very distinct stripes and is obviously a brindle, but the Skye Terrier just appears to be a muddy grey/brown. The main way we can tell this Skye is brindled is simply its muddy-coloured coat - this colour occurs almost exclusively on brindles and never on normal solid reds or sables. It also appears to have some lighter and darker areas, which also suggest it is a brindle. This Glen of Imaal's brindling is very obvious on the short fur on its body, but less obvious on the longer fur on its head. If the Skye above were to be shaved down, it would look something like this.
The Wolfhound and Deerhound show brindling on wirey coats. On the first two dogs, greying has caused the black striping to fade out.
Brindle Tan Points and Saddle Markings
Because the brindle gene allows expression of the A locus, any A locus coat patterns can show brindling on their red sections. The main patterns are sable (AyAy) and tan points (atat). A sable brindle will appear solid brindle (in fact, all solid brindles are sables), although any areas of shading will remain dark. A tan pointed dog with the brindle gene will appear black with brindle points instead of tan. All of these dogs display black-pigmented dogs with brindled points, with or without white markings.
These two dogs are brindle with saddle markings(atat plus an unknown modifier, see the Agouti page). Note the large areas of solid black on the back and brindled tan on the legs and head. The Cardigan Welsh Corgi also shows white in the irish spotting pattern.
Liver and Dilute Brindles
A brindle dog will have liver (brown) stripes if it is bb on the B locus, blue stripes if it is dd on the D locus, and isabella stripes if it is both dd and bb. Dilution affects phaeomelanin (red) too to some extent, so the base colour will be relatively light (certainly not a deep red colour, but more likely cream). Here are three blue brindles. The Whippet is a very light brindle, and the blue colouration is mostly visible on the mask and nose. The Neapolitan Mastiff, on the other hand, is a heavy brindle, so the overall appearance is blue.
On some light brindles there may be solid red areas where it appears stripes are "missing". This is particularly common in Whippets, but the genetic basis is unknown. Have a look at the Whippet below. In the first picture the brindle appears normal - however in the third picture you can see a large clear area on the dog's side.
Please, check the MERLES section.
- K: Black (solid black all over). Overrides A (agouti) series. Any genes on the A locus will not be expressed. - kbr:Brindle (black stripes on a red base). kbr is dominant over k, so a dog only needs one kbr in order to be brindle (but will be overriden by one K gene). Brindle dogs will express whichever genes are on their A locus, but the red parts of the coat (phaeomelanin) will be brindled (black parts will not be affected). - k: Non-solid black. A kk dog will express whichever genes are on its A locus.
M locus ("merle series", affects intensity of eumelanin)
The first dog has very few black patches, and they are mainly quite small. The second dog shows the normal merle pattern - a mixture of larger and smaller patches, covering roughly 50% of the body. This pattern is generally the most preferred in breed standards. The third dog has very large black patches, sometimes referred to as blanketing. The last dog is known as a minimal merle. It is almost completely black with just a very small amount of merling. This pattern is rare and generally discouraged because it can "hide" the merle gene if the black covers up all the merle in the coat. Dogs with little or no visible merling are sometimes called cryptic merles.
The dogs above are called "blue merles" because of the bluish colour between the patches in their coat. This is a widely-used term but is actually misleading. Technically they should be "black merles". Their nose pigment is black and their eyes are brown or blue. They are able to make normal eumelanin in their coat, so their patches are black. If they didn't have the merle gene, they would be solid black. "Blue merle" is misleading because it seems to say that these dogs have blue pigment (dd acting on black - see Dilution page), when in fact they have black.
An example of the genotype of one of the above dogs would be: BBDDEEggMmSSKK (most of these aren't necessarily homozygous, but I will assume they are for ease, otherwise I'd have to keep saying, "KK, kK or Kk" etc). The genotype translates as: no liver colour (BB), no dilution (DD), no mask or recessive red (EE), no greying (gg), merle (Mm), no white spotting (SS), and solid black (KK).
Two solid blue merles (the Border Collie also has white in the irish spotting pattern and bronzing on its side).
This mixed breed could be classed as a cryptic merle as one side of the dog is almost completely solid black. The merling is only visible on the right side (first photo). This dog also has tan points (atat) and white spotting in the irish pattern.
Examples of the variation in base colour of merles. In some cases the black may be diluted almost to white, but it is mostly somewhere between light "powder" grey and dark "grizzled" grey. It is not certain whether this variation has a genetic basis.
Eyes and Noses
The random coat dilution caused by merle also affects the eyes and nose. The eyes may be all or partly blue, and the nose may be all or partly pink. Above are examples of "butterfly" noses on merles, which are partly pink.
The harlequin Great Dane here also shows a butterfly nose and wall eyes (one blue, one brown). Harlequin is a modified type of merle where the areas between the patches are diluted completely to white. See the Harlequin page for more information.
Sometimes merles have patches that are only partially diluted, and are between the base and the patch colour. These are known as dilute spots, and they may sometimes appear brownish. The Australian Shepherd above has a large dilute spot on its knee.
A normal "blue" merle becomes a "red" merle when it has bb on the B locus, i.e. when it has the liver gene. "Red merle" is also a misleading term because "red" is usually used to refer to phaeomelanin (tan, gold, cream etc) rather than eumelanin. A red merle should correctly be called a liver merle. Liver turns all of the patches on a blue merle into brown and the colour between the patches becomes pale brown. As with all livers, liver merles have liver noses and amber eyes. Here we have two long-haired Dachshunds. The dog at the back is a red (liver) merle with tan points, and the dog in the front is a normal blue (black) merle with tan points.
More examples of liver merles with tan markings and with or without white.
As the examples in the sections above have shown, merles can come with or without any of the tan patterns (A locus). The most common is normal tan points, but creeping tan and saddle patterns also occur. All dogs which show tan markings must be kk on the K locus (K is dominant black, so if a dog has even one copy of it then they will be solid black, or solid merle if they are also Mm, regardless of what they have on the A locus). A tan pointed dog will be atat on the A locus (tan points are recessive and only dominant over recessive black, a, so a dog must have two at genes to display tan points).
The Norwegian Dunker is one of the only breeds where the saddle pattern and the merle gene occur together. This dog's pattern is between creeping tan and saddle. You can see that the merling covers the back, the tail, the back of the neck and the top of the head. The tan is very light and so is probably affected by the Intensity, which lightens red. This dog also has white in the irish spotting pattern. The Dunker photo was taken by June.
A dog which is Eme, EmE or EmEm on the E locus will have a mask (Em, the mask gene, is dominant). The mask can be black, liver, blue or isabella depending on the dog's pigment. If the dog also has the merle gene, the mask will be merled. Because of this, masks are not be visible on solid merle dogs - they're just merled like the rest of the coat. However, tan-pointed merles with little to no face white sometimes display masks (recognisable because the areas which should be tan on the muzzle are merled instead). Sable (ayay) dogs have masks which are much easier to see. A dog which is ayayEmEmMm (homozygous for sable, homozygous for mask, heterozygous for merle) will appear solid red with a merled mask.
A dog with AyAy on the A locus and kk on the K locus (allowing for the A locus markings to be visible) will be a sable. Sables are solid red with or without black tipping. Sometimes, especially if sable is combined with a mask, the black tipping can be quite extensive and can cause large black areas on the back, head and tail. In a sable merle, all of these black areas are merled. As you can imagine, how obvious it is that a dog is a sable merle depends heavily on how much black tipping they have. A sable merle with no black tipping (a "clear sable") will just appear to be a solid sable, possibly with one or two blue eyes (the only indication that they are a merle). In some breeds, such as Shetland Sheepdogs and Rough Collies, a slightly different version of sable exists. This type consists of brownish hairs on the back and head (even though these dogs have black pigment), and is often called "shaded sable". On this type of sable coat, merling can be quite visible (if there is a lot of dark brown shading) or very hard to see (if the shading is lighter and not so extensive). However, the merling is usually visible at birth, so breeders will generally know if their dogs are sable merles or just sables. A sable merle will have some faint, darker brown/tan patches on a lighter base, and the merling will usually be confined to the back and head. It is often most visible on the ears, where the fur is shorter.
Simon is also a shaded sable merle. These pictures show him from five months to 2 years old. His shorter puppy coat displays the merle much more clearly than his longer adult coat.
Grizzle / Agouti
Haiku shows beautifully the effect of merle on agouti (aw). The agouti pattern consists of banded hairs scattered over the dog (and mostly concentrated on the head and back). As only the black (eumelanin) parts are affected by the merle gene, the overall effect of merle on grizzle is of scattered small black spots and flecks, with some patterns forming where the black would usually be on the grizzle (as can easily be seen in the photo of Haiku to the front, where the spots on his head form lines). These two alleles do not generally occur within the same breeds, so grizzle/agouti merle is very rare and is usually seen on Husky crosses. Haiku the Husky mix, photos by Dariana Kamenova:
If a dog is kbrkbr (or kbrk, because kbr is dominant over k) on the K locus then any phaeomelanin (red) in their coat will be brindled. This applies to merle dogs too - there is no reason why a merle cannot also have brindle. If a merle dog is kbrkbr and has atat on the A locus then it will be merle with brindled tan points. If a merle dog is kbrkbr and AyAy (sable), it will be solid red with brindling all over ( and possibly with larger areas of black than is normal for a brindle on the back and/or head, if the sable has dark shading). The brindle in both the brindle-pointed merle and the solid brindle dog will be broken up into uneven spots rather than being complete stripes. This is because the stripes on a brindle are eumelanin (affected by merle, so random parts are diluted) and the base is phaeomelanin (not affected by merle). A solid brindle merle is relatively easy to identify because of its broken-up stripes. However, when a merle dog has just brindle points it can be harder to recognise because the stripes are even less visible. The points will generally have a few black spots on them and will appear a darkish, muddy brown.
The Cardigan Welsh Corgi is one of the few breeds where brindle and merle regularly occur together (the other main one being the Catahoula Leopard Dog). The dog on the left has tan points, but they are very dull and brownish compared to normal tan points (see the dog on the right, which does not have the brindle allele). This points to this dog being a brindle-pointed blue merle, which is very common in the breed. The brindle appears only on the points, where it is broken up by the merle gene. In this case, the dog is a very light-marked merle, so the points are very washed out with few spots. Brindle can also appear on merles with the creeping tan and saddle patterns.
A dog with TT or Tt on the T locus will have ticking on any white areas in their coat. It is thought that TT produces roan or heavy ticking and Tt produces lighter ticking. Ticking will only show up on a merle if it has white markings, and the ticking will be a mix of the merle base colour and the patch colour (so in a blue merle, black and grey).
Recessive red is when a dog has the genotype ee on the E locus. This means it is unable to produce eumelanin (except in its nose and eyes), and can only produce phaeomelanin, so its coat is red all over (except for any white markings). Merle only affects eumelanin, so if there's none there, there can't be any merle. Just like with clear sable, a recessive red merle can be impossible to distinguish from a non-merle dog. It will simply appear solid red, and the only giveaway is if it has one or two blue eyes.
Lastly, we need to mention dilutes. A dilute is a dog which is dd on the D locus. dd stops a dog from producing full eumelanin pigment and also affects phaeomelanin to a lesser extent, meaning that the pigment it produces is weak and pale. It turns a black dog into a blue dog with a blue nose and amber eyes) and a liver dog into an isabella. A merle with the dilution gene will appear very washed-out. The black or liver patches will be diluted almost to the same shade as the base colour. So a blue merle (a proper blue merle with the dilution gene, not a black merle like the ones we've been dealing with so far! will appear almost completely light grey with some faint darker grey patches, and an isabella merle will be light greyish brown with faint darker brown patches. On a longhaired dog, it can be next to impossible to tell a blue or isabella merle from a non-merle. To distinguish between a merle with dilution and a merle with greying (which produces much the same effect on the patches in the coat), look at the nose. If the dog has a blue nose, it has the dilution gene.
A double merle is one which is homozygous. That means it has two copies of the dominant M gene, so its genotype is MM. This impairs its ability to make pigment. Double merles are typically mostly white and have merle patches on the head and sometimes the body. They do not necessarily have the allele for piebald, although if they do, they are likely to have even more white than double merles without a white spotting allele), but the MM genotype causes loss of pigment to such an extent that it tends to remain only on the upper areas of the dog - the top of the head, the back and the base of the tail, similar to the extreme spotting pattern. Sometimes double merles are even born completely white. The nose is generally mostly or all pink, and the eyes are generally wall or blue.
This Dachshund is a blue (black) double merle with tan called a double "dapple" in this breed). She has a large amount of colour on her body, probably because she has been bred from solid merle parents rather than merles with white spotting the amount of white on the merle parents tends to affect the amount of white on the double merle puppy, so high-white parents will generally produce higher-white puppies, but she does have a lot of white on her face. The eye on the side with the white is blue because of the lack of pigment, and she has a butterfly nose.
This Border Collie type has a typical double merle coat pattern. However, the full pigment on the nose and around the eyes suggests that she may in fact just be a high-white normal merle. It would be unusual for a double merle to have so much pigment.
Photos by Cat of Dog Rad Design
Here we have a probable harlequin double merle. Harlequins are merles with a modifier that changes the way the merle looks (see the page on merle modifiers). The same principles therefore apply to harlequin double merles as do to normal double merles - the patches will generally be smaller and confined to the head and the back, and there will often be a more pronounced lack of pigment around the eyes and nose.
The breeding of double merles is generally frowned upon, not just because double merle dogs rarely match breed standards (for example, a double merle Dachshund like Casey above would be disqualified for too much white and bad pigment), but also because of the health problems linked to them. Some double merles are perfectly healthy, but eye defects and deafness (due to lack of pigment in parts of the inner ear) are common, as well as sunburn and skin cancer on exposed pink areas.
Merle puppies are circled in blue and double merles are circled in red. Non merles are not circled.
It's clear from this that breeding a double merle to a non merle is the only way to get a completely merle litter. Double merle to non merle and merle to non merle are the only "safe" breedings - i.e. the only ones which cannot produce double merle puppies. Breeding merles of any sort (single or double) together is always risky. I haven't included a Punnet square for a double/double breeding, but that one is easy enough to work out - each parent can only possibly pass on the M gene, so all puppies will be MM (double). Because of this, double merles should never be bred together.
Double merles are often referred to as "lethal whites". This is an incorrect and misleading term. There is nothing lethal about the merle gene, it can just be problematic. Lethal white is a completely separate gene which does not occur in dogs. It occurs in horses, and is recessive, unlike the dominant merle in dogs. Lethal white (also known as Overo Lethal White Syndrome) kills 100% of horses which are homozygous for the gene. A lethal white will be completely white with blue eyes. It is unable to produce any pigment, like an albino, and because the cells in the intestine are linked (embryonically) to the cells which control skin pigment, they don't develop properly. The intestine is therefore contracted and lethal white foals are unable to pass faeces. This eventually results in death.
Sometimes black and white dogs with heavy ticking or roaning can be mistaken for merles. The main giveaway is that a ticked or roaned dog will have very uneven grey areas, with flecks of white showing through. Also, if the dog has tan points, they will be ticked too (if they're on the "white" areas rather than the black patches), whereas in a merle they would be solid, and the patches on a blue roan or ticked dog will be more regular than on a merle (appearing only on the back and head in the piebald or extreme white pattern, rather than all over the dog). In addition, if the dog has a butterfly nose or any blue in its eyes then it is most likely a merle as these pigment issues do not generally affect roaned dogs. All of these dogs are merle "look-a-likes", but none of their breeds (English Cocker Spaniel, Australian Cattle Dog and Basset Bleu de Gascogne) actually carry merle:
- M: Merle (black patches on a grey base). Dilutes random sections of the coat to a lighter colour, leaving patches of full pigment. Phaeomelanin is not affected - only areas of eumelanin can be merled. - m: Non-merle (normal expression of eumelanin).
Breeds With the Merle Allele Australian Shepherd Catahoula Leopard Dog Dunker Border Collie Old English Sheepdog Mudi Cardigan Welsh Corgi Collie (Rough and Smooth) Shetland Sheepdog Dachshund (known as dapple) Beauceron Bergamasco Pyrenean Shepherd Great Dane
S locus ("spotting series", affects distribution of all pigment)
White spotting on dogs is mostly determined by the genes on the S locus. When we use the term "white spotting" we simply mean white areas, not actually white spots. White spotting can occur on any colour, and will cover up both eumelanin and phaeomelanin. In technical terms this is known as epistasis. So any dog can have white markings, whether they are black, blue, liver, isabella, brindle, sable, tan-pointed, merle or whatever.
White hair occurs when the skin cells are unable to produce any pigment. The white spotting gene impairs the ability of cells on particular parts of the skin to make pigment, so the skin becomes pink and the fur white. Nails and paw pads will also become pink in areas where pigment is not produced.
Currently, only two white alleles have been proven to exist on the S locus: S - no white sp - piebald
A third allele may exist for "extreme white" (sw), however this has not been proven and so far all dogs with high white have been shown to be homozygous for sp instead. The white spotting alleles are thought to be examples of incomplete dominance. This means that a heterozygous dog will express its most dominant gene, but may also be affected by the more recessive one to a lesser extent. For example an Ssp dog may have some white spotting (see below). However, the relationship between the alleles is complicated and can vary between breeds.
It has recently been shown that some dogs with white spotting do not have an sp allele at all. These are mostly dogs with "true" irish spotting (in other words, irish spotting that breeds true - this should be made clear further down the page). The allele that causes this pattern has not yet been identified and it is not known if it is also located on the S locus. For the purposes of this site we will refer to this gene as si, but remember that this may not be accurate.
Spread of White
Whichever white pattern a dog has, its white will always follow the same rules of spread. White starts on the farthest "edges" of the dog - the tail tip, the tip of the muzzle, the paws and the tip of the breastbone. This is known as the "trim" pattern. From there it spreads to cover the muzzle and forehead, the front of the chest, the lower legs and more of the tailtip, creating irish spotting. Next it spreads round from the front to the back of the neck, and creeps up the legs and tail. On a piebald dog, only the head, back and tail base may still be coloured. The back colouring is the next to go, followed by the tail base, then the face markings. The ears will always remain coloured unless the dog has a very high amount of white. The ears are generally the last part of the dog to turn white.
Of course the idea of white "spreading" is mainly metaphorical, to give you a picture of how white patterning works. White doesn't spread like this on one particular dog (i.e. you won't get a solid coloured puppy that gradually loses colour as it grows, until it's almost white! Although puppies do often lose or gain a little colour as they grow), it's just to show which areas remain coloured on dogs with more and more white. One way to think of it is that the dog retains colour best in the most important areas of its body - around its internal organs (body and tail base patches) and its brain (ears and face patches) - and loses colour easiest from the parts farthest from these areas. In technical terms, pigment "migrates" to different parts of the body during the development of the embryo, and the S gene determines how far the pigment migrates. Sometimes it simply doesn't reach the furthest extremities (this can be caused by a minor problem or illness during development), and this can result in a small amount of white trim on a dog without sp, for example a small chest patch on an otherwise solid-coloured dog.
The white rules aren't set in stone - sometimes individual dogs can have unusual white patterns, where, for example, the white on the legs is very uneven, or they have piebald patches in unexpected places, like on the neck or chest. However, in general, they do hold relatively true.
Residual White and White Trim
A very small amount of white on the chest, toes or tail may occur when the pigment doesn't migrate fully as the embryo develops. This is known as residual white and has no genetic basis. If a slightly larger amount of white is present then the dog may be heterozygous for sp, in other words Ssp. In a breed such as the Newfoundland you may get such a dog from crossing a "Landseer" (piebald, spsp) with a solid (SS). However, in breeds carrying piebald there is no real way to know whether minimal white markings are just residual white or indicate the presence of the piebald gene without genetic testing or test breeding, as piebald heterozygotes may have anything from a tiny chest spot to pseudo-irish markings (see below).
We can assume that the two dogs above are SS and that their markings are just residual white. This is because neither breed comes in piebald or irish spotting. If either of these dogs did have an sp or si gene then we would expect to see dogs with much more white being produced in these breeds. As it is, their white is non-genetic and breeding two dogs with white markings in these breeds will not necessarily produce puppies with any white at all.
This Staffie is a possible piebald heterozygote (i.e. carrier of the piebald allele). We cannot know for sure, but this is the most likely explanation for its white chest patch as the Staffie breed is known to commonly have the piebald gene. If this dog were bred to another sp carrier then some of the puppies may be piebalds and have much more white than either of their parents.
Irish Spotting Pattern
Irish spotting (si) is the pattern sometimes known as "boston" or "mantle", although these terms do not always refer to "true" irish spotting. On a dog with irish spotting, white is found on the legs, the tip of the tail, the chest, neck and muzzle. Many dogs with this pattern have a full white neck ring and a blaze.
True irish spotting is caused by an as yet unidentified gene, but we can assume irish spotted dogs to be homozygous for the gene (sisi) as it breeds true. This means that two irish spotted dogs bred together will produce puppies with irish spotting. We can assume that a solid dog bred to an irish spotted dog will produce a heterozygous dog with less white.
The Aussies, Border Collie and Bernese Mountain Dog shown here are all true irish spotted. None of these breeds regularly come in piebald or extreme white and their white markings breed true (implying they are homozygotes).
"Pseudo" irish spotting may look the same or very similar to true irish spotting, but is in fact not caused by sisi but by Ssp, i.e. these dogs are heterozyous piebalds. The incomplete dominance of S means that an Ssp dog may show up to roughly half the amount of white as an spsp dog. These dogs do not breed true and when two are crossed the puppies may be solid, piebald or inbetween. See below for an example of this in Boxers.
Note that not all Ssp dogs show much white, or in some cases any white at all. The amount of white on a piebald heterozygote appears to vary drastically and some may look exactly like homozygous solids. The three breeds (Staffie, Podengo Portugueso and English Pointer) all carry piebald but are not known to carry irish spotting, so these dogs are most likely pseudo-irish. A true irish spotted dog will not usually have white on the hips/knees or underside of the body, so this is another clue that sp is present.
Finally, a "flashy" irish spotted dog (one with more white than usual) may be caused by a combination of si and sp. If a true irish spotted dog also carries an sp allele then the normal white pattern may be extended. This supports the theory that si is actually on a different locus, as the two alleles appear to be inherited completely separately. This has been shown to occur in Shelties, where dogs carrying the sp allele as well as irish spotting can usually be identified by having more white around the neck and underside of the body. An spsp Sheltie has a high amount of white and is known as a "colour-headed white". Shelties are one breed known to carry both true irish spotting and the sp allele, but many breeds only have one or the other.
Piebald (spsp) usually produces a coloured head (with or without white on the muzzle and as a blaze), and patches on the body. Generally the base of the tail is coloured, but other than that the patches may be located anywhere on the body (but rarely on the legs).
Because piebald is a recessive gene and heterozygotes piebald carriers don't always have any white markings, it can remain hidden and pop up unexpectedly. Both the Poodle (as shown here) and the Shar Pei, traditionally solid-coloured breeds, occasionally produce piebald.
Extreme White Pattern
The extreme white pattern consists of a completely or predominantly white dog with just small amounts of colour on its head and sometimes base of tail. Small body patches may sometimes be present too. Sometimes the nose is pink or partly pink, and the eyes may be blue in some breeds due to lack of pigment. So far all extreme white dogs that have undergone genetic testing have been shown to be homozygous for the piebald gene (spsp), just like the piebalds in the section above. However, as there is a fairly large difference between those dogs and the ones shown below, it is possible there is something else going on to cause the high white. In breeds with both true irish spotting and piebald the high white may simply be caused by the interaction between homozygous irish spotting and homozygous piebald (e.g. the Sheltie). In other breeds the cause is less obvious and has led some people to postulate a further S allele - sw.
Extreme white can occasionally cause problems when it removes large amounts of pigment from the face and ears. The most common problem is deafness (due to lack of pigment in certain parts of the inner ear, which prevents it from functioning properly), but dogs with exposed unpigmented (pink) skin are also more prone to skin cancer than those with more pigment.
Split Faces and White Heads
There is thought to be a separate gene or modifier that causes some dogs with irish spotting or the piebald pattern to have a split or completely white face. A split face is when half of the face is white and the other half is coloured. This pattern occurs often on double merles, but it's just a natural part of the double merle pattern, and is not caused by any extra genes. It's only when it appears on irish spotted and piebald dogs that it raises eyebrows.
Ticking and Roan
Any white areas on a dog may be ticked or roaned due to the T gene. The ticking corresponds to the colour the area of the coat would have been if it wasn't white.
Believe it or not, the two Australian Cattle Dogs are extreme white piebalds. The solid black patches on their heads are their actual markings, and the solid appearance of the rest of the coat is created by very heavy roaning. The Large Munsterlander to the right shows heavy ticking on a piebald dog.
Boxers generally come in what appears to be the irish spotting pattern, so we would expect most examples of the breed to have sisi on the S locus. However, sometimes Boxer puppies are born which are completely or almost completely white. How these puppies could be regularly born to parents with much more colour perplexed Boxer breeders for a long time.
However, we can now provide an answer to this. Boxers do not have the si allele, but supposedly irish spotted Boxers are actually pseudo-irish - i.e. Ssp. When two pseudo-irish dogs are bred together some of the puppies will be homozygous piebalds (spsp).
White puppies can therefore be avoided by always breeding pseudo-irish dogs to solid dogs. A solid dog will be SS and therefore there is no possibility of heterozygous sp dogs. A solid dog will not necessarily have no white markings at all however.
The fashion for "flashy" Boxers in the show ring means that many white puppies are born. Luckily these are now usually sold as pets rather than culled.
Sometimes white can occur on dogs separately to the S locus white spotting. One example is as part of the double merle pattern. A double merle will almost always have more white than its parents, and will often appear to have the piebald or extreme white pattern when in fact it does not carry those alleles. The harlequin gene also causes a similar effect. See the double merle page and merle modifiers page for more information.
White can also occur due to dilution of phaeomelanin by the I locus. Phaeomelanin is red pigment, and the I locus can dilute it to cream or sometimes white. Breeds such as the Samoyed have this second type of dilution, so they appear completely white but in fact it's not due to white spotting. They are in fact recessive red (so they cannot produce any black pigment) with dilution of their red pigment to white, resulting in a solid white dog with black nose pigment.
The main way to tell a dog with extreme white spotting apart from a dog with phaeomelanin dilution is to look at the pigment on the nose, lips and eyerims. A dog with extreme white spotting is likely to be missing some pigment in these areas, so they will be partly or completely pink. A dog with phaeomelanin dilution will have solid black in all these areas (possibly with a dudley nose, which are common on dogs with dilution).
These two dogs (a Finnish Lapphund and a Siberian Husky) are genetically black and tan (atat), but with dilution of their tan points to white. It can be easy to mistake diluted points for white markings, but points will generally be in a very regular and symmetrical pattern, with two chest spots and a vent spot, and spots above the eyes. The white will also be confined to the sides of the muzzle and not the top (except in a dog with creeping tan). The Husky has actual white spotting as well, but its cheek pattern gives it away as a black and tan.
One of these dogs is not like the others, but which is it? All are "false" whites except for one, which is an extreme white piebald. If you guessed the Staffie, you'd be right. She has pink around her eyes, ears, muzzle and underside - a sign of lack of pigment, associated with extreme whites, and a few dark spots on her ears. All the other dogs are recessive reds (ee) or clear sables with phaeomelanin dilution. Note the slight cream sheen on the coat of the German Spitz, Samoyed and Shiba, and the jet black lip and eye rim pigment on all of them. The Shiba has a dudley nose, often associated with recessive red.
- S: No white (all of coat is pigmented - no white spotting). - sp: Piebald - homozygous causes over 50% white, with large pigmented patches on a white base). Heterozygous piebalds may have varying amounts of white, from none at all to "pseudo-irish" (phenotypically the same pattern as irish spotting but not caused by the same allele - si: Irish spotting white on muzzle, neck, chest, feet and tail tip. This type of white spotting may not actually be on the S locus but I have included it here for lack of anywhere else to put it! Homozygous sp causes irish markings and heterozygous may have any amount of white inbetween solid and irish.
T locus "ticking series", affects distribution of all pigment)
Ticking and Roan
Ticking is flecks or spots of colour on white areas. It can occur on any white area on a dog, so long as the white is "proper" white ( i.e. so long as it's caused by the white spotting series and not by the chinchilla gene). If a dog has the ticking allele but doesn't have any white areas, there will be no visible effect.
The gene which codes for ticking has not been found yet, but it is thought to be dominant. It has been assigned its own locus - T - and there are traditionally thought be two alleles on that locus. According to the common theory, T is the dominant ticking allele, and t is the recessive clear white allele.
However, this theory does not account for the full variation in ticking and roan in dogs. It is probable that there are at least four T-locus alleles. Recent genetic research has proven ticking and roan to be distinct (but mapped to a similar area), so my own guess is that the T-series is most likely as follows:
T - ticking Tr - roan Td - Dalmatian spots t - clear white
It is not clear how these genes interact or what their order of dominance is, although ticking, roan and Dalmatian spots all appear to be dominant to their absence.
Ticking amount varies greatly between dogs, and this can be partly explained by the idea of incomplete dominance. If the ticking gene (T) displays incomplete dominance over the clear white gene (t), then a TT dog would have heavy ticking and a Tt dog would have lighter ticking. It is not clear whether this is also true for roan and Dalmatian spots.
Generally, ticking is heaviest on the legs and the muzzle. If a dog has only a small amount of ticking, it will appear in these areas before appearing anywhere else. Roan, on the other hand, is more even over the whole body.
The colour of ticking/roan corresponds to the colour that the area would have been if there wasn't any white there. For example, a black-and-tan dog with white markings and ticking would have black ticking on its body and tan ticking on its legs, chest and muzzle, where it would be tan if it didn't have white. The English Setter below shows this well.
Roan is a pattern which produces heavily mottled white areas. Often only a small amount of scattered white is visible.
The three dogs are extreme examples of roan. The Australian Cattle Dog and Basset Bleu de Gascogne are genetically black-and-tan, so the roaning is black on the body and tan on the points. With the Cattle Dog, the whole dog would be white if it didn't have roaning (note there are no black patches), as it is an extreme white piebald. The overall effect on the black areas of these dogs is similar to the "salt-and-pepper" colour found on Schnauzers, except if you got a close-up look at the hairs, you'd be able to see that they're not banded like the hairs on Schnauzers are. The Basset Bleu perhaps gives a better indication that roan actually consists of lots of spots, packed very densely to cover most of the white. This has led some people to believe that roan is, in fact, just very heavy ticking. However, others believe that it is controlled by a separate gene, and recent studies appear to have confirmed this. The German Shorthaired Pointer shows liver roan. The roan here is even more dense and difficult to distinguish from the solid liver patches on the back and head.
Black dogs with roaning often appear a greyish colour, and are commonly called "blue roans". The Cocker Spaniel above is a blue roans. Just like with "blue merles", these dogs are called "blue" but aren't actually genetically blue. The term "blue" is usually used to refer to black dogs with the dilute gene (dd), which dilutes the coat and nose to grey and the eyes to amber, but neither blue roans nor blue merles have this gene.
By contrast, these three dogs show light ticking. They are probably heterozygous for the ticking allele (Tt). As you can see, the ticking is mostly on the legs and muzzle. A dog homozygous for the ticking allele (TT) is more likely to be ticked all over.
These gundogs show heavier ticking and are mostly likely TT.
This Great Dane looks like it has ticking, but in fact the black spots are caused by the harlequin gene. It is genetically a merle, with its grey areas diluted to white. If you look carefully you can just about see a spot of actual white on its chest. This actual white is clear of ticking.
Dogs with ticking or roan are generally born white. The ticking/roaning develops as the dog grows. This can be rather dramatic, as in the Australian Cattle Dog. There is a popular myth that Australian Cattle Dogs are born white because of their Dalmatian ancestry. In fact, they are born white simply because they have the extreme white spotting pattern with roaned white areas. The roaning takes a while to develop, but the extreme white spotting is there from birth, hence the puppies are completely or almost completely white.
Dalmatian spots puzzled geneticists for a long time. They are completely unique to the breed and do not occur anywhere else in the dog world. Contrary to looks, Dalmatian spots and the harlequin pattern in Great Danes are not related.
It is now fairly certain that Dalmatian spots are in fact a modified form of ticking. One of the main differences between standard ticking and Dalmatian spots is that the spots are often more sparse on a Dalmatian, bigger, and do not get more dense on the legs and muzzle. These are all probably to do with the modifier.
As well as the obvious similarity in looks between a dog with ticking and a Dalmatian, there are a few other things which indicate that spots are modified ticking:
- Dalmatians are born white and develop their spots later on.
- Dalmatians occasionally have patches on their head and/or body, as with the dog on the right above). These suggest that they have the piebald pattern, meaning that the spots can't be caused by any of the white genes. The high rate of deafness amongst Dalmatians also supports this high white piebald is sometimes associated with deafness, as in white Boxers.
- Dalmatian crossbreeds are often ticked and never, as far as I am aware, spotted. This suggests that there is a recessive modifier behind Dalmatian ticking, so the Dalmatian parent passes down one copy of the modifier, but unless it's bred to another Dalmatian, there will never be another copy of the modifier, so it cannot be expressed).
- Sometimes Dalmatians are born which display some ticking or roaning - effectively "muddying" the base white. This is probably caused by a slight mutation or error in the modifier, stopping it from being expressed normally.
- T: Ticking white areas are ticked with small flecks or spots of colour). Ticking is whichever colour would have been on that area if the dog did not have white. Suspected to be another case of incomplete dominance - a TT dog has heavier ticking than a Tt dog. - Tr: Roan more dense than ticking - Td: Dalmatian spots - large, round ticking spots - t: Clear white - no ticking on white areas.
A Summary of the Summary
A locus - Ay - sable aw - agouti/wolf grey at - tan points a - recessive black
B locus - B - non-liver b - liver
D locus - D - no dilution d - dilution of eumelanin to blue or isabella
E locus - Em - black mask E - normal extension (no mask) Eg - grizzle/domino e - recessive red
G locus - G - greying g - no greying
H locus - H - harlequin h - non-harlequin
I locus -br>Alleles unknownK locus - K - solid black kbr - brindle k - non-solid black
M locus - M - merle m - non-merle
S locus - S - no white spotting sp - piebald si - irish spotting (may not be on S locus)
T locus - T - ticking Tr - roan Td - Dalmatian spots t - no ticking
A locus alleles will only be expressed when a dog does not have a dominant black (K) gene. S locus alleles (white spotting) appear on top of anything else a dog has - there is nothing that can mask them except for, possibly, I locus alleles, which may make them difficult to see. D and B locus alleles for liver and dilution will override all alleles for black (dominant or recessive) and change all eumelanin on the dog. E locus alleles are not overriden by anything except for the I (intensity) and S (white spotting) locii, so recessive red will be expressed even on a dominant black dog. Black masks will be expressed also but may not be visible on a black dog. The H locus will only be expressed on a dog with the merle allele (M locus) and the T locus will only be expressed on a dog with white spotting (S locus).
Here's a genotype for a dog which we are going to decipher to work out what the dog would actually look like:
That looks daunting, so let's take each pair of genes individually, referring back to the summary of series above to see what each letter means:
Ayat - one allele for tan points, and one for sable. Sable is dominant over tan points, so the dog will be sable. Bb - one allele for liver and one for normal expression of eumelanin. So the dog will not have liver pigment, as the liver allele is recessive. dd - two allele for dilution of eumelanin. So the dog will express blue eumelanin. eEm - one allele for recessive red, one for a eumelanin mask. Mask is dominant over recessive red, so the dog will have a mask. gg - two alleles for no greying. So the dog will not have greying. Hh - one allele for harlequin, one for non-harlequin. So the dog will express harlequin if it is also merle. kk - two alleles for non-solid black. So the dog will not be solid black and will express its A-locus alleles. mm - two alleles for non-merle. So the dog will not be merle. SS - two alleles for no white spotting. So the dog will have no white. Tt - one allele for ticking, one for no ticking. So the dog will have some ticking.
So our dog will have sable (which can show through because there is no dominant black allele to stop them from being expressed), it will be a dilute because it is dd, so it'll have blue eumelanin. It'll have the gene for harlequin but won't express it because it has no merle gene. Likewise, it'll have the gene for ticking but can't express that either because it has no white. It also has no no greying, no brindle, and no recessive red, but it does have a mask.
What we've ended up with is a blue sable ("fawn") with a mask:
DOG NOSE COLORS The material is proudly presented by
The default nose colour for dogs is Black, but a number of genes can affect nose colour.
Liver Liver (bb) dogs and dilute liver (isabella, dd) have noses ranging from deep brown to pink. Liver pigment does not seem to be retained in the nose as easily as black pigment, so many high-white liver dogs have completely pink noses. It is genetically impossible for a liver dog to have a black or blue nose.
Colour range in liver dogs:
Colour range in isabella dogs:
As you can see, it can be impossible to tell a liver-pigmented dog from an liver dilute just by the nose, as the colour ranges are almost identical. However, you may notice a purplish tinge to the nose of an isabella which is not usually present on a liver.
Blue Blue (dd) dogs have noses ranging from light grey to almost black. It is genetically impossible for a blue dog to have a brown nose. Note, however, that sometimes grey dogs can occur that don't have the blue dilution gene. So an apparently "blue" dog may have a black nose and dark eyes, because in fact it is a black dog with the greying gene rather than a proper blue dilute. Sometimes blues can also be very dark, so that their coat and nose appear almost black. It can be very difficult to tell whether such dogs are blacks or blues.
Colour range in blue dogs:
Butterfly or Parti Nose A "butterfly" nose is when a dog has patches of bright pink on its nose leather. These patches are randomly located and can cover any amount of the nose, from just a tiny pink spot to almost the whole nose. Butterfly noses sometimes occur on dogs with the extreme white spotting pattern (e.g. white Boxers, Bull Terriers and Dogo Argentinos), but generally they're associated with merles. Not all merles have butterfly noses though - double merles and normal merles with less dark patches than normal are more prone to them, and they are very common in harlequin Great Danes.
Butterfly noses are created when parts of the nose have no pigment (the colour pink is associated with a lack of pigment). The merle gene dilutes random parts of the pigment on the coat and nose, creating grey areas on the coat and pink areas on the nose. Harlequin Great Danes have an extra gene which dilutes the grey areas on the merle to white, so this extra strong dilution means harlequins are highly likely to have a butterfly nose.
The non-pink parts of the nose can be liver, blue or isabella if the dog is bb (liver) and/or dd (dilute). Livers and isabellas often have very light noses anyway, sometimes bright pink, so a butterfly nose may not show up on a liver or isabella merle (the whole nose may just appear pink). The first example below shows a liver merle with a visible butterfly nose.
Dudley Nose Sometimes, in specific breeds such as the Bull Terrier, the term "dudley nose" is used to describe a dog with a pink nose due to high white on the face (see butterfly nose above). However, usually it's used to describe a dog with pigment loss on its nose. Generally the pigment loss on a dudley nose is in the middle of the nose, spreading outwards to cover almost all of the nose on some dogs. The pigment loss causes the nose to become lighter in these areas, usually ending up as a dull pink. Dudley noses never lose their pigment completely and are never as bright pink as butterfly noses or even the pink noses found on liver dogs. There is also always a darker area remaining around the edge of the nose.
Dudley noses are generally seen on dogs with solid black noses only, simply because the lighter pigment on liver, isabella and blue dogs means that areas with pigment loss are very hard to see. They are, however, very common on black-nosed dogs, including show dogs.
Snow Nose Also known as a "winter nose", this is a dudley nose that appears during the winter months, or sometimes as a result of stress or other factors. Dudley noses are permanent, but snow noses are not.
Nose Injury Injury to the nose can sometimes result in pigment loss, either permanent or temporary. This dog has injured its nose, probably quite recently. You can see stripes of pink and red where the pigment has been damaged.
DOG EYE COLORS The material is proudly presented by
The default eye colour for dogs is brown: However, a number of genes can affect eye colour.
Amber Eyes Amber eyes usually occur when the eumelanin produced is diluted or modified by the recessive genes in the B or D series. In other words, all liver dogs (bb) have amber eyes, and so do blue and isabella dogs (dd). Occasionally dogs with black pigment also have amber eyes, but in general they are found just on livers and dilutes. Amber eyes vary from light brown (overlapping with the lighter eyes sometimes found in black-pigmented dogs) to yellow, yellow-green or grey.
Isabella (dd) Weimaraner, showing very light eyes that almost match the shade of its coat.
Liver grizzle/agouti Siberian Husky. The pink/brown nose gives this dog away as a liver.
This English Springer shows very light amber eyes for a liver.
Blue Eyes Genetically, there are four ways in which a dog can have blue eyes. Three of these are linked with pigment loss in the coat.
The most common way is as a side effect of the merle gene. Merle dilutes random parts of the pigment, including the eyes and nose. This sort of dilution causes blue colour in the iris (contrary to common belief, animals with no pigment around their eyes do not always have pink or red eyes like albino rodents do - lack of pigment or very diluted pigment often results in blue eyes, as it does in albino humans). Because of the random pigment loss, often merle dogs have "butterfly" noses (see nose page) and blue, wall or split eyes. Wall eyes are when a dog has one blue eye and one brown or amber eye, and a split eye has some blue in it and the rest is brown or amber. Split eyes vary from mostly blue to mostly brown or amber.
The more dilution there is in the coat of a merle (i.e. the more grey/diluted areas), the more likely they are to have blue eyes or a butterfly nose. A heavily merled dog (large areas of black or liver) is unlikely to have either of these traits. Double (homozygous) merles are highly likely to have blue eyes and a completely or almost completely pink nose because of the combination of merle dilution and large amounts of white around the face. This red (liver) merle Aussie has one amber eye (because of its bb liver pigment) and one blue. If you look carefully you can see a sliver of blue in the amber eye.
The merle Cardigan Welsh Corgi shown here has two solid blue eyes.
This merle Border Collie has very striking light blue eyes, which is surprising as its merling is fairly heavy.
The second way in which blue eyes can occur is when a dog has large amounts of white around its eyes. White areas on the coat are where the cells are unable to produce any pigment, so if these areas spread to the face then there may be pigment loss in the eyes and on the nose, making the nose pink and the eyes blue. This only tends to occur on very high-white dogs with the extreme spotting pattern, such as white Boxers, and even then is fairly unusual.
The third way is when a dog is affected by the C series. The C series is albino. There are no confirmed cases of true albinism in dogs, however "white" Dobermanns have a very light coat (with the main coat appearing as a very light isabella colour and the tan points light cream), blue eyes and a fully pink nose, and this is thought to be a form of albinism.
Lastly, blue eyes can be inherited as a completely separate gene, unaffected by coat colour. This gene is, however, rare. It is rumoured to occur occasionally in the Border Collie, but mainly it's seen in the Siberian Husky. Huskies can have one or both blue eyes, regardless of their main coat colour, ranging in shade from almost white to sky blue. This is particularly striking when seen on black dogs.
These two Huskies have almost identical coat colours, but one has two deep brown eyes and the other has one blue eye (eyes of different colours are known as "wall eyes"): As you can see, both dogs have full black nose pigment and black around the eyes - eye rims, so the only explanation for the blue eye on the dog on the right is that it is inherited separately to coat colour and pigmentation.
A Husky with two blue eyes.
This mixed breed has wall eyes, but is not a merle (the greyish areas are roaned white). This means it must have the independent blue eye gene, which is most likely from a Border Collie or Husky parent. The large amount of Husky crosses with blue or wall eyes suggests that the independent blue eye gene is dominant, in Huskies at least.
The recessive blue eye allele also appears to crop up in Beagles such as this one. Note the jet black eyerim pigment and the colour surrounding the eyes, proving that the blue eye is not due to white spotting.
DOG COAT COLOR TERMS The material is proudly presented by
The frustrating thing about dog genetics is the vast array of different names given to the same colours in different breeds. For example, genetically recessive red Labradors are "yellow" but Golden Retrievers are "golden". You can't have a golden Labrador or a yellow Golden Retriever, yet they are genetically the same colour! This can be a bit of a barrier when it comes to working out the genetics of particular breeds, so to make things easier, here's a list of some of the terms you will find (either on breed standards or just being used by breeders), and what they actually mean in terms of the genetics we've studied on this site.
Just a diagram with some of the main terms used to describe body parts in dogs. This may help if you're trying to interpret breed standards.
What it means
Not thought to be real albino, just a dog with very, very diluted pigment
American Cocker Spaniel
Any solid colour other than black
Various - general term
Isabella (liver dilute, bbdd) or very washed-out red
Various - general term
When hairs have bands of more than one colour. Associated with agouti (aw)
Various, but mainly Cavalier King Charles Spaniel and King Charles Spaniel (English Toy Spaniel)
Coloured spot in the middle of the forehead blaze on a piebald dog
Sable with black tipping
Roan or heavy ticking in any colour
Black and white with no tan markings
Blue merle and white with no tan markings
Samoyed, American Eskimo
Cream (appearing either as patches or on the whole of the dog)
Black and silver
Various - general term
Black with tan points (atat) which have been diluted to off-white by the Intensity gene
Various - general term
Heavily brindled dog (i.e. with thick black stripes, so very little red shows through)
Cavalier King Charles Spaniel and King Charles Spaniel (English Toy Spaniel)
Deep, clear red (recessive red, ee) with white markings in the piebald pattern. The same colour as the Red and White Setter
Basenji, Rat Terrier
Sable with blue (diluted black, dd) pigment, or sable with isabella (diluted liver, bbdd) pigment, giving a grey/blue cast to the coat
Various - general term
Black-pigmented dog with roaned white, which appears a bluish colour
Great Dane, Boston Terrier
Black (or brindle) dog with white markings in the irish spotting pattern
Harlequin with brindle patches
Various - general term
A brownish cast to the coat of a longhaired black dog, usually caused by sun bleaching
Various - general term
Partly pink nose on a merle
Various - general term
Very dark blue dilute (dd), often appearing almost black
Brindle or fawn (sable) boxer with the piebald white pattern
Various, but particularly the Labrador
Various - general term
One solid colour all over (i.e. no sabling on a red dog). Clear-coloured dogs may still have white markings (white is not a colour)
Reddish liver (bb)
Various - general term
Pattern inbetween traditional tan points and saddle. Generally the tan covers the whole of the muzzle and eyebrows, most of the legs, and the front of the chest. Probably caused by a modifier that extends the normal tan points
Various - general term
Merle dog with little or no visible merling, i.e. one which appears solid black (or liver, etc)
Various - general term
A merle dog with a dark grey base coat (rather than the usual light grey). This is caused by intermingled black hairs
Chesapeake Bay Retriever
Light liver-pigmented red. A duller shade than sedge.
Various - general term
Patch on a merle which is lighter than the other dark patches
Usually a dog with a greyish/brown back and cream/white underparts, caused by the grizzle gene (Eg)
Various - general term
Dark line along the back, often caused by sabling
Various - general term
Pink or liver nose
Various - general term
Clear sable, usually with a black mask
Isabella (dilute liver) with tan points
Harlequin Great Dane with sable (fawn) patches rather than black. Black patches may still appear on the muzzle, where most Danes have black masks
Various - general term
Sable merle. In clear sables, merle may only be visible on the mask (if present)
Various - general term
A dog with more white than normal for its breed, or a dog with clear white (no ticking)
Various - general term
Cardigan Welsh Corgi
Brindle merle with an orangey base coat
Black/brown with tan points/underparts. Caused by grizzle gene Eg, as in domino Afghan Hounds
Intermingled brown and black hairs (usually on a saddle)
Merle dog with white patches in its merling (caused by an unidentified modifier - probably the same as tweed)
Blue merle with tan points
Merle modifier which dilutes the grey parts on a merle to white, leaving jet black patches on a white base. Overall appearance is similar to a Holstein cow
Black brindle (brindle with very thick black stripes). When the coat grows in, such dogs can appear to be a brownish colour, like liver but without liver pigment
Various - general term
Dilute liver (bb on the B locus and dd on the D locus)
A light, dullish red dog with a blue mask and blue sabling (so a blue dilute sable, dd)
Off-white (light cream), caused by dilution of phaeomelanin (red). May have a black or liver saddle.
Various - general term
A solid white dog with a slight cream sheen
Cavalier King Charles Spaniel and King Charles Spaniel (English Toy Spaniel)
Black with traditional tan markings (atat)
Light purplish tongue colour on a dilute Shar Pei
Light red (and red)
Light reddish liver (bb). Dark liver is called copper in this breed.
Various - general term
Blue (diluted black, dd)
White markings in the irish spotting pattern (muzzle, neck, chest, lower legs and tail tip)
Various - general term
Black (or liver, isabella, or blue) on the muzzle area (may include the eyebrows and the ears), caused by the Em gene
Merlequin (aka merlekin, merlikin)
Double merle. The double merle causes broken patches of merle on a white base, giving a pattern similar to harlequin (but more regular)
Various - general term
Merle dog with very little visible merling. In effect, an almost completely black (or liver, etc) dog with just a small patch of diluted fur
Various - general term
Generally a red dog with random black sections on its coat, caused by a very rare somatic mutation
A red or tan spot on an otherwise black-spotted Dalmatian. Caused by a mutation
Various - general term
Blue merle with a brownish sheen to the grey parts of the coat
Dandie Dinmont Terrier
Light tan (probably sable) with white furnishings and head
Various - general term
Black brindle (thick black stripes)
Various - general term
Any dog with two distinct colours in its coat
Isabella (diluted liver, bbdd)
Various - general term
Black lines on the toes of a tan-pointed dog
Dandie Dinmont Terrier
Black with tan points (atat) diluted to white by the Intensity gene. The black is diluted to silver by the progressive greying gene (G). Appearance is of a light grey dog with white underparts.
Various - general term
Dog which has the merle gene, but is solid red because of the recessive red gene (ee) or clear sable. As there is no visible merling, it can be impossible to tell the dog is a merle
Various - general term
Tan markings above the eyebrows and on the cheeks on a tan-pointed dog
Various - general term
Various - general term
Markings (usually tan, or a variant of) on the sides of the muzzle, the neck, chest, eyebrows, lower legs and vent
Harlequin with patches of any colour other than black
Various - general term
Pale-coloured merle with only a few dark patches
Cavalier King Charles Spaniel and King Charles Spaniel (English Toy Spaniel)
Tricolour (black with tan points and white markings)
Australian Cattle Dog
Various - general term
Black brindle (very heavy black striping)
Cavalier King Charles Spaniel and King Charles Spaniel (English Toy Spaniel)
Deep, clear red (recessive red, ee)
German Shepherd Dog
Agouti or wolf grey (aw)
Salt and pepper
Wolf grey (agouti, aw, with very strong dilution of phaeomelanin, turning the red to white). Appears as a grey dog with white points in the traditional tan point pattern. On longer fur, banded hairs are visible
Various - general term
Appears black with a brownish tinge. Genetic basis is unknown.
Chesapeake Bay Retriever
Liver-pigmented sable, sometimes with a liver mask
Shaded red sable with urajiro markings
Various - general term
Brindle with greyish stripes (but not a blue brindle - silver brindles are not dilutes)
Various - general term
Dark blue (which is diluted black, dd)
Various - general term
Merle with diluted pigment, dd (i.e. a proper 'blue' merle!)
Various - general term
Sable with black sabling "muddying" the red. Sometimes called a sabled fawn.
Cream colour around the eyes on a wolf grey dog
Various - general term
Light brindle with sparse stripes
Various - general term
Literally "three colours". Usually a black and tan-pointed dog with white markings (to any extent), although liver, blue and isabella tris occur too
Terriers and hounds
Tan dog with a black saddle and white markings (to any extent)
Various - general term
A small amount of white on the chest, muzzle, toes and/or tail tip
Various - general term
Brindle tricolour (i.e. black with brindle points and white markings. Brindle never appears as the main colour on a tan-pointed dog)
Tweed (tweed merle)
Various - general term
Modified merle, causing patches of brown and tan to appear on a blue merle.
Shiba Inu and others
White markings on the underside, roughly following the same pattern as tan points. Urajiro is caused by a specific gene and affects only phaeomelanin (red)
Various - general term
Tan patch under the tail on a tan-pointed dog
Various - general term
White reaching all the way around the neck
Various - general term
Brown or black marking running down the middle of the forehead on a shaded sable dog
Various - general term
Agouti (aw) with phaeomelanin dilution turning the base coat to grey and the points to cream, leaving some black on the back. This is the colour of the Keeshond and Norwegian Elkhound.
A somatic mutation is a mutation that occurs in the body cells after the embryo has begun to form. Cells are divided into two categories - germline cells (i.e. gametes) and somatic cells (all other body cells). When a mutation occurs at the point of conception (when the first cell begins to replicate) then this mutation may enter the germline and so be passed on to future generations, but after this point the two types of cell replicate separately and any mutations occuring in the somatic cells will only be passed on to the descendents of those cells and will not be passed to the next generation. This is because only the information carried in the gametes will go on to form a new individual - of course, mutations may well happen in the gametes too during the individual's lifetime, and these mutations will be passed on.
This may sound complicated, so perhaps an example will make it clearer. Cancer is a somatic mutation. Sometimes a mutation occurs in a cell that makes the cell "immortal". Most cells can only replicate a certain amount of times, but when this particular mutation happens the cell is able to replicate itself indefinitely - this is the biological definition of immortal, and this is how tumours form and also why they can be very difficult to get rid of. However, although the predisposition to cancer may be genetic, cancer itself is not as it occurs as a mutation in cells which will not go on to form new individuals.
Another type of somatic mutation in dogs involves pigment. If a pigment mutation takes place during the development of the embryo, patches of another colour may appear on the puppy. This is most often seen as black patches on recessive red Labradors and Golden Retrievers (it is not certain why it seems to appear in these breeds more than others). The painting at the top of the page shows what this often looks like. All it takes is for one cell to mutate early on in development - then all cells descended from that one as the embryo grows will be the different colour. Due to the mutation these patches effectively have a different genotype to the rest of the dog, and this is sometimes known as mosaicism.
A very rare form of mosaicism is the chimera. A chimera is a single animal that is the combination of two separate embryos. You may have heard this term used to describe creatures with the DNA of two different species spliced together, such as human/mouse embryos created in labs, but it also occurs naturally when two fertilised eggs combine very early in development. Effectively, the resulting animal is two individuals in one. It has patches of one set of DNA and patches of the other as well. Sometimes it can be impossible to tell a chimera without genetic testing (particularly in humans), but in some cases the resulting animal may be a combination of two different colours. I do not know of any proven dog chimeras, but the effect may be similar to the somatic mutations already discussed, but more extensive (roughly 50/50 of each colour in random patches).
This incredible Labrador appears to show somatic mutations, but is a possible chimera due to the extent of his patching. These photos were taken at a rescue centre in France and sent to me by Damien Ricco but we have been unable to locate the original photographer.
Vitiligo is a condition where the skin/coat cells stop being able to produce pigment, causing areas of white. It can have a variety of causes (including an auto immune disease that attacks pigment cells), but in dogs does not usually have any adverse effects other than coat colour. The pigment loss is generally concentrated around the head/face, but often spreads to the rest of the body.
Phaergus, the Newfoundland above, has developed what appears to be vitiligo on his head, chest, back and tail. The first picture shows Phaergus in May 2010 (at 3 years old), and the second shows him in March 2011. Phaergus and his photos belong to Bobbi Walker.
I have not seen this phenomenon in any other breeds but it appears to occur fairly frequently in black Greyhounds. There are small white spots on the coat, almost like ticking in reverse. These dogs look like they have been sprinkled with snow. It is not clear whether this is caused by some form of greying, vitiligo, or whether it is actually a colour gene. Vitiligo is unlikely as this is usually concentrated around the face and not in small spots all over the body.
Other Strange Things
This unusual pattern appears to occur only in Finnish Lapphunds. Some are darker than this - but all have the tan spectacles around the eyes. It does not fit any of the usual tan patterns, although the spectacles are reminiscent of agouti.
There are a few colour genes which can occasionally cause health problems in dogs, most notably merle.
Double Merles and High Whites A homozygous (or "double") merle is one with two copies of the merle gene, and this severely impairs its ability to make pigment, leaving large areas of the dog pigmentless (white). Pigment is actually necessary for certain parts of the body to function correctly, so lack of pigment can cause health problems. Dogs with large amounts of white caused by the homozygous piebald allele (sp), such as Bull Terriers, Boxers and Dalmatians, can also have some of the same health problems as double merles, particularly deafness (which is a huge problem in Dalmatians).
Lack of pigment in particular parts of the inner ear can cause deafness, which can be unilateral (just one ear) or bilateral (both ears). It is commonly claimed that dogs with white ears are always deaf, but in fact it's been shown that whether or not pigment is visible on the outer ear does not affect whether or not the dog can hear. In other words, a dog may have coloured ears but still be deaf, and a dog with white ears will not necessarily have any problems.
The double merle gene can also cause eye deformities. This is because the location of the eye cells in an embryo happens to be the same place that pigment starts to appear. If there is a problem with the pigment, this can therefore affect the development of the eyes. Problems include irregularly-shaped pupils, subluxated pupils (not positioned in the right place), microphthalmia (abnormally small eyes, usually with impaired vision), and other, less visible abnormalities causing blindness and bad vision.
Lack of pigment anywhere on the dog can make the skin much more sensitive to the sun. This is a particular problem on the nose, as it is so exposed, but any area of pink skin is susceptible to sunburn and skin cancer. The same problem occurs with any animal which has little or no pigment. White cats are probably the most well-known example. Skin cancer rates in white cats are extremely high and a surprising proportion of cats with white ears end up having their eartips amputated to stop the spread of cancer. The main way to prevent sunburn in animals is the same as with humans - apply suncream!
Dilutes There is a common misconception that dilutes are in some way naturally sickly - this is not in fact the case. The dilution gene does impair the ability of the cells to make pigment, but only in that it causes the pigment that is made to be less intense. As with most recessives, the dilute allele is in some way "faulty", but it is only faulty in its ability to produce full-strength eumelanin. The ability or inability of the cells to produce full-strength eumelanin does not affect the health of the dog, simply its colour.
That said, the idea of dilutes as unhealthy most likely has its foundations in Colour Dilution Alopecia. This is an apparently genetic disease causing hair loss and skin problems. A dog with this disorder will typically appear "mangy" and have partial hair loss. It is usually reported from blue dogs, particularly Dobermanns, but presumably it affects isabella dogs too diluted livers. Any colour can carry CDA or be homozygous for it, but only blues and isabellas will have symptoms.
CDA does not occur on all dilutes and its frequency varies between breeds. It is particularly common in Dobermanns, occuring in up to 80% of dilute dogs. Dilutes in other species such as mice are caused by the same gene, and yet CDA is not known in these, implying it is not an unavoidable consequence of dilution. It is thought that CDA may be caused by a specific dilution gene - labelled dl. Just as there are various different b alleles that all cause the liver colour (phenotypically the same, so only distinguishable through genetic testing), it is probable that there are a number of different d alleles as well, and only one of these causes CDA. What this means is that CDA is most likely caused by a recessive allele but could theoretically be bred out of most lines by careful breeding and genetic testing.
This blue German Pinscher appears to have mild alopecia. Its coat is dull rather than having a healthy shine, and it seems thin and patchy.
The same problem can also occur (albeit rarely) on black or liver dogs, and is known as Black Hair Follicular Dysplasia. It affects black/liver hairs only, leaving all other hairs as normal. Because this condition is so rare, it often goes undiagnosed. I used to know a Jack Russell Terrier mix who was white except for a black patch on his back, which was hairless. His condition puzzled a whole string of vets and skin specialists, who suggested various types of mange and allergies, and he was never properly diagnosed as having Black Hair Follicular Dysplasia. Unfortunately for dogs with genetic hair loss conditions, there is no cure, although these conditions do not generally cause the dog to be itchy or uncomfortable and so are mostly harmless.
Two Different Types of Pigment The key to understanding dog genetics is simply this: there are two types of pigment which create coat colour in dogs (and most other mammals). Pigment is just the thing that gives each strand of hair its colour, just like pigment in paint or dye, or pigment in your own hair. All coat colours and patterns in dogs are created by these two pigments, which are both forms of melanin. Each of the pigments has a "default" colour, and it can then be changed by various genes.
Eumelanin is, by default, black pigment. All black areas on a dog are caused by cells producing eumelanin. However, there are genes which turn eumelanin into other colours - liver (brown), blue (grey), or isabella (a dusty pale brown). If a dog has any of the genes to turn its black eumelanin into liver, blue or isabella then all of the black in its coat will be changed. This is because these genes restrict and/or alter the production of eumelanin, so the cells aren't able to produce full-strength pigment. We call blue and isabella dogs "dilutes" for this reason. They either lack the genes which tell their cells how to produce proper eumelanin, or their cells know how to produce it but can't.
As well as being found in the coat, eumelanin is present in the other parts of the dog that need colour - most notably the eyes (irises) and nose. The nose will be black, liver, blue or isabella depending on the type of eumelanin the dog can produce. The colour in irises is produced by layers of pigment, and brown eyes like most dogs have (and like many people have too) are caused by black eumelanin in those layers. When a dog has altered/restricted production of eumelanin, the irises are also unable to produce full-strength eumelanin. This means that the dark pigment in the eye becomes lighter, and the eyes turn into a light brown colour, known as amber or gold. This isn't really a colour we find in human irises, so it's hard to illustrate it with an example. The closest we have are hazel eyes, which are a mixture of green and brown, and so appear lighter than normal brown eyes.
This shows the variation in colour of eumelanin. Black is the default, then it can be turned into liver by one set of genes, and black and liver can be turned into blue or isabella by another set of genes. Blue is diluted black and isabella is diluted liver.
When we talk of dogs that are "black pigmented", "liver pigmented", etc, we mean that is the colour of eumelanin that the dog can produce. Sometimes these dogs have no eumelanin at all in their coats (their skin cells produce only the other type of pigment, phaeomelanin), but we can tell what their "pigment colour" is by looking at their nose. A black nose means the dog produces black eumelanin, and so on. It's confusing to talk of a dog's "pigment colour" like this, because as we know, eumelanin isn't the only type of pigment. But it's common practice, and I'll be using such terms a bit on this site.
The second type of pigment, in some ways less important than eumelanin, is phaeomelanin. This is red pigment. The term "red" covers everything from deep red (like Irish Setters) to light cream, encompassing gold, yellow and orange. Whenever we talk of red, unless we're talking particularly about Setters, we mean the whole range of tan colours.
Phaeomelanin is produced only in the coat. It does not occur in the eyes or the nose, so any genes which affect the colour/intensity of phaeomelanin will not affect the eyes or nose. Only eumelanin occurs in those areas, and so only genes which affect eumelanin can affect the eye or nose colour.
This shows the variation in colour of phaeomelanin. Unlike eumelanin, it doesn't occur in two distinct colours (black and liver, with dilutes counting as shades of those), but rather just one colour, which varies in intensity. The most intense phaeomelanin colour is Irish Setter red. The default colour is probably golden, with different genes causing it to be more or less intense (i.e. telling the cells to produce a higher density of pigment particles, so making the colour stronger, or a lower density, making the colour weaker, so lighter). So far so good, but this doesn't seem to explain all the coat colours in dogs - how about white?
White isn't really a colour, so white hair on animals isn't caused by pigment but a lack of pigment. In dogs it is a lack of both eumelanin and phaeomelanin. White areas on animals are simply caused when the cells cannot or do not produce any pigment at all. Sometimes the whole animal is affected, like in albinos, and sometimes just parts of it are affected, like in dogs with white markings. It can affect the production of eumelanin in eyes and noses too, turning noses pink and eyes blue (or red in proper albinos). There is also a second type of white, which is caused by dilution of red (phaeomelanin) pigment, making the cells produce fewer pigment particles than normal, so the colour gets lighter. If it is diluted enough, it can become white. Many white dogs have a slight ivory/cream sheen to their coats because their cells are still producing a very small amount of pigment. This sort of white does not usually affect eumelanin, so any black/liver/blue/isabella areas on the coat will stay dark, and the eyes and nose will do too.
Distribution of Pigment
The colour genes in dogs do two things - they determine the eumelanin and phaeomelanin colours/shades, and they control the distribution of these two pigments. They tell certain cells to produce eumelanin, others to produce phaeomelanin, and sometimes they tell them to not produce pigment at all. Exactly which cells are told to produce what is determined by the exact set of genes, although it can be random to a certain degree (e.g. puppies may have slightly different white markings to their parents, or patches in different places). Sometimes genes can even tell cells to switch which type of pigment they are producing every once in a while. This means that as a hair grows, it becomes banded with black and red, because the cell produces black (eumelanin) for a while, then changes to red (phaeomelanin), then back to black, etc. It's a bit like when you highlight your hair and after a while the roots start to show through. The overall colour of an animal with this sort of black and red banding will generally be a muddy brown from a distance, and close up you will be able to see the black parts of the hairs. It's called agouti, and it's the colour of wild rabbits and mice, as well as a large amount of other mammals. It's popular amongst wild animals because it provides very good camouflage. It also occurs in dogs, but it looks a bit different, like the colour of a wild wolf rather than a rabbit and isn't very common.
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Getting Started As we have discussed already, every dog has a set of locii (points on its strand of DNA) with two genes on each one. For example, on the B locus they might have the genes B and b, b and b, or B and B. These are picked from a list of possible genes for each locus, which for the B locus is just simply B and b, but for other locii there may be a longer list (the A series, for example, has five possible genes - Ay, aw, as, at and a).
When dogs breed (and every other mammal, including humans), each parent passes on just one gene from each of its locii. This gene is picked at random, so each of the two genes has an equal chance (50%) of being passed on. However, it isn't just a case of the same gene being passed on to all the puppies.
When a sperm cell fertilises an egg, an embryo starts to develop. The sperm cell is just one of thousands that have been produced by the male dog. Each sperm cell is an individual. It carries half the information needed to create a new life, and that information consists of one set of genes. This means it has one gene from each of the male dog's locii, and which of the two genes that is is entirely random. There are lots of different genes, so the exact combination carried by the sperm cell may well be pretty unique.
Egg cells are exactly the same - they also carry one set of genes from the parent - one from each pair. However, fewer of them are produced, as, obviously, it wouldn't be good to have more than a certain amount fertilised at the same time.
Just a few out of the thousands of sperm produced will actually reach the eggs in the female dog's womb. The rest will die. The ones that do reach an egg will join with it and insert their nucleus, which is the part of the cell that carries the genetic information (in this case, the incomplete strand of DNA), into the egg. The nucleii of the egg and the sperm then join together to create a new nucleus which carries all the necessary genetic information to develop into an embryo.
So we can see that genetics involves a lot of random chances. Because of this, it's hard to be certain of anything when you breed a pair of dogs. We can't say that the puppies will definitely be this colour or that pattern. All we can do is predict the chance that the puppy will be a certain colour. It's important to remember this when reading the rest of this page. When predicting litters we usually give at least four possible outcomes for the puppies. This does not mean that you will get four puppies and one will be each of those colours. All it means is that each puppy has a 25% chance of being each colour. Occasionally you may even end up with each puppy in the litter inheriting the same genes and so being the same colour; it just depends on which sperm reach the eggs. It's like throwing dice. Sometimes you may be unlucky or lucky, if you're playing a board game! and get six sixes in a row. That seems really unlikely, but actually, each time you throw the die, the chance of getting a six is the same. Each throw is independent of all the others (the chance of getting a six the second time is not dependent on whether you got a six the first time), and genetics is very similar. Just because only one in six of the puppies are supposed to pure white according to our calculations, it doesn't mean that if the first pup born is white, the second is any less likely to be white too!
Labrador Case Study
Now that we have a basic idea of how breeding works, let's look at a case study. Let's say we have lots of Labradors, and we are going to breed them. Not in some bizarre, frenzied dog orgy, of course, but a pair at a time. First, we decide we want some black puppies, so we pick two lovely, shiny black dogs. Let's call them Blackie and Sooty, because we're uninventive.
We breed Blackie and Sooty, and we get this litter:
Well that all seems to be in order. We bred a black dog with a black dog and we got black puppies. Seems to make sense, doesn't it?
Enthused by the success of our first litter, and anxious to breed some more black puppies to sell to the black Lab-loving public, we choose two more black dogs: Jet and Ed.
We breed Jet and Ed and get this litter:
Looks good... but oh! Hang on a sec! One of those puppies is brown. How on earth did that happen?
Our surprise at getting this chocolate-coloured puppy leads us to look up dog colour genetics on the internet. It turns out that whether a dog is black or liver (chocolate/brown) depends on the genes it has on a particular locus - the B locus. There are two possible genes - B is black, and it's dominant over b, which is liver. Here's a list of the possible genotypes and what dogs with those genotypes would look like: BB - two copies of black, so puppy will be black. Bb or bB - one copy of black, one of liver. Black is dominant, so puppy will be black. bb - two copies of liver. Puppy doesn't carry any black, so it must be liver.
Punnet Squares The mystery of the chocolate puppy can be solved by working out the genotypes of the parents. We can see from the list above that if a dog is black, it must be BB or Bb. If we calculate some breeding results from all the possible crossings of BB/Bb dogs, we can work out which breeding/s will produce chocolate puppies, and so from that we can tell the genotypes of the parents.
The quickest and easiest way to calculate breeding results is to use a Punnet square. Firstly we'll see what happens when we breed a Bb dog with a BB dog.
This is a blank Punnet square, ready for us to fill in. As you can see, there are two rows and two columns. The number of cells in the table, not including the ones we will put the column and row titles i is four, so we'll get four puppy options each time we fill it in.
First we put the genotype of each parent in the boxes at the top and the side (the title cells). We put just one gene letter in each cell, and it doesn't matter which parent goes across the top and which down the side - it makes no difference to the results.
Now we need to fill it in. Each of the four cells represents one possible puppy genotype. To work them out, we trace up from the cell to the column title and across to the row title. It doesn't matter which order we do this in, whether we look at the row or the column first, but I usually do column then row.
Here's the finished Punnet square. If we refer back to the list above, we can see that all the puppies in this litter would be black. There are no bb puppies, and they're the only dogs that can be liver. So we haven't found Jet and Ed's genotypes yet. We need to keep looking!
Crossing a BB dog with another BB dog will obviously only produce BB puppies, so Ed and Jet cannot both be BB. From the example above we now also know that it can't be right that one of them is BB and the other Bb. So the only other option we can try out is Bb x Bb:
So that's three black puppies (BB, Bb and bB), and one liver! It looks like we've found what we were looking for. Because the liver gene (b) is recessive, it can be hidden, which means a dog can carry one copy of it without expressing (displaying) it. That means that two dogs carrying liver can be black themselves, but produce liver puppies. It's a bit of a problem when it comes to breeding, actually, because recessive traits, such as liver and dilution, can remain hidden in lines for many generations, then suddenly crop up when a dog carrying the trait is bred to another with it (if the gene is very rare in the breed then it can be a long time until this happens, if it ever does). This is why breedings sometimes throw complete surprises, like silver (blue) Labrador puppies in a breed which, to all intents and purposes, contains no silver at all. That one lone recessive silver gene (d, on the D locus) has been passed down from generation to generation, completely unknown to the breeders, until finally it's met another one. It might have come from a cross breeding with another breed many years ago, which doesn't show up on the pedigrees and no longer has any effect on the look of the dog, so all the dogs in the line look exactly like normal Labradors. Such rare recessive traits can be impossible to eradicate from a breed, simply because you can't tell which dogs carry them. In recent years, however, genetic testing has helped to identify the carriers.
Anyway, so now we know that Jet and Ed both have the genotype Bb. However, if we wanted to get liver puppies in the future by just breeding black dogs, how would we know which black dogs are Bb and which are BB, without doing any genetic testing? Luckily for us liver is quite common in Labs, so it's not like trying to find out which Labs carry silver, where you could do hundreds of test breedings and still not get silver pups because the chances of finding another dog with the gene are so slim. The way to tell if a black dog is Bb or BB is to breed it to a liver.
We can be certain that the liver parent will be bb, because it can't be anything else. If the black parent is BB, we'll end up with all black pups, because each pup can only possibly inherit B from the black parent. All of the puppies will have the genotype Bb. But if the black parent is Bb, half of the puppies will be liver. How do we know this?
By doing a quick Punnet square:
The resulting puppies will be:
So if any of the puppies in the litter are liver, the black parent must be a carrier of of the liver gene, so it must have the genotype Bb.
Lastly, it's important to note that due to the nature of recessive genes, the only breeding which will produce all liver puppies is bb x bb, so two liver parents.
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