No matter how a dog's coat colour is described, the genetics that create the colour are always the same. But sometimes colours that look alike are caused by different genes.

Why is Huckleberry Hound blue? Can a dog be striped like a tiger? Why are some dogs born with spots, while other dogs get spots as they get older? The answer lies in the genes that control coat colour. In dogs, there are really just two basic colours: black and red. Genetic modifiers can cause those colours to become lighter, striped, mottled or spotted, or to be combined with white markings, tan points or a face mask. The following are some of the more common colours and patterns and how to recognize and describe them.

Variations on the red colour in Labrador Retrievers: traditional yellow and fox red.

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The Base Coat Colours in Dogs: Black and Red

The genetics of coat, nose and eye colour in dogs is complex, so this article will only touch on the most basic ways of explaining colour.

Black is true black, like a black Labrador Retriever and black Cocker Spaniel. Black dogs always have black noses and dark eyes. Some may have a modifying gene that causes the nose to fade to a pinkish shade in winter (called a snow nose) or to fade to brown or pink as the dog ages, but always the edge of the nose will retain the black pigment. Black is a dominant colour, meaning only one copy of it is needed to make a dog's coat black.

The recessive version of black is brown (also called chocolate or liver). A dog with two black genes is black. A dog with one black gene and one brown gene will be black, but is said to be a "carrier" of the brown colour. A dog with two brown genes will be brown. A brown dog can have a brown or pink nose and light brown, hazel or golden eyes, but it will never have a black nose.

Red coats are, in essence, "not-black" coats. The red colour ranges from dark mahogany red like an Irish Setter to light orange. The coat colour becomes more intense as the dog matures from puppy to adult. Yellow, which ranges from fox-red (dark reddish orange) to nearly white, was once thought to be genetically separate from red, but now it appears that both red and yellow are genetically the same base colour, so from now on in this article it is referred to simply as red. Modifying genes that control the intensity of the colour determine whether the coat colour will be dark red, golden, palest cream or somewhere in between.

Nose and eye colours vary in red dogs, because the gene that makes the coat red does not affect them. Therefore, some red dogs have black noses and dark brown eyes, some have brown noses and light brown eyes and some have pink noses and amber eyes. Again, these are affected by the presence of other genes.

Dilute Coat Colours in Dogs

The base colours of black, brown and red can be changed to a lighter colour if there are two copies of a modifying dilution gene present. A dog born with a dilute colour will be that colour at birth and will stay that colour, although the shade may change slightly over time. All dilution genes affect the coat, nose and eyes. A dog with one copy of the gene will be a carrier, able to pass it on, but will appear to be the normal colour of black, brown or red.

Blue is caused by a gene that changes black to a grey-blue colour. The gene that changes black to blue also changes the nose to grey and the eyes to a light colour (blue or yellow). This is found in Great Danes, Doberman Pinschers, American Pit Bull Terriers and many other breeds.

Fawn (also called Isabella) is the dilution of brown. It has many names, depending on the breed. It is a greyish-tan shade, different from the “fawn” used to describe many yellow dogs. The nose will be a similar colour to the coat and eyes will be light coloured. This is the colour of a Weimaraner and of a fawn Doberman.

Buff (also called chinchilla) is the dilution of red. This is not a lighter shade of red, but an actual bleaching out of the colour. Dark and medium red becomes sort of a dusty greyish-brown, while the lighter red shades of orange and gold become a silver-gold or platinum shade. The nose will be a greyish-pink and the eyes will be light. Buff is occasionally found in Nova Scotia Duck Tolling Retrievers (where it is undesirable). All Chesapeake Bay Retrievers carry two copies of this gene, creating the desired "dead grass" colour.

Patterns Affecting the Dog's Base Colour: Agouti and Its Variations

In addition to the main base colour of a dog, there can be other genes that organize coloured hairs into specific patterns. Some dogs have more than one pattern, creating interesting combinations. The Agouti gene is the basic version of a series of genes that do this. The different types of agouti always causes some dark hair to be light or partly light coloured, so it can be based on any colour.

The true agouti pattern, or wild colour, is often called wolf grey. It is found in many breeds, and is best represented by the Norwegian Elkhound and Keeshond. In a true agouti, each individual hair will have horizontal bands of light and dark colour of differing widths.

Sable is a variation of agouti in which the light hairs on the body are tipped with black to varying degrees, instead of being banded. Some dogs have a lot of black shading in the coat, while others only have a little. It can be difficult to tell by looking at some dogs to know whether the pattern is true agouti or sable.

Tan points is another variation of agouti in which the light and dark hairs are organized much more specifically. A tan-pointed dog will have tan markings on the sides of the face, a spot over each eye, tan triangles on the chest, and tan on the lower legs and under the tail. The Doberman and Rottweiler are breeds that are always tan-pointed. Sometimes modifiers affect the depth of the tan colour, so it can range all the way from dark mahogany red to gold, cream or almost white. Tan points can be combined with any base colour.

Saddle is caused by a modifier working on the tan-pointed pattern. These dogs are born with tan points, but as they get older, the black recedes, leaving more and more tan. The amount of back remaining varies from a lot to almost none. Airedale Terriers are good examples of this pattern.

Some dogs have a face mask. A mask always is the same as the nose colour. Boxers, Great Danes and Mastiffs all have masks. Some masks are so large that they "spill" onto the entire head, ears and chest, something commonly seen in Belgian Tervurens and Belgian Malinois, as well as some other breeds. When a mask is combined with tan points, it can cover up the points on the face. This is often seen in German Shepherds. Red masks on a red dog can be very hard to see, since the colour of the mask and body coat may be nearly the same.

A brindle (striped) dog can have just a few stripes or be covered with stripes, and the length and width of the stripes can vary widely. As with the other agouti variations, brindle can occur with any base colour. The stripes may be dark or light, depending on the presence of dilution genes, but they are always darker than the base coat. If the dog appears mostly dark with a few lighter stripes, it is because there are so many stripes grouped so close together that the lighter colour is almost completely hidden by the stripes. This is commonly called reverse brindle.

In a tan-pointed dog with a gene for brindle, only the tan markings will have visible stripes.

Cream Dogs, White Dogs, and Dogs With White Markings

Cream Golden Retriever. This is the lightest shade of red. (Handler: Colin Brownlee)

The colour "white" is actually a complete absence of any colour in the hair. Some dogs that are called white are actually the very palest version of red. These are dogs with a gene that reduces the intensity of red colour to the point where there is, in essence, no colour remaining in the hair. Since this gene does not affect black or brown, the eyes and nose stay dark. The West Highland White Terrier and Maltese are perfect examples. Some white dogs also come in cream or biscuit with dark eyes and noses, including Samoyeds, Golden Retrievers, Poodles and White Shepherds.

Other white dogs are actually particolour (spotted) dogs in which the spots are so small that they seem to have completely vanished, as if all the colour that should be there has fallen right off the dog. This is found in several breeds, including the Dogo Argentino. Generally, a close examination of such a dog will show some spots of pigment inside the ears and around the eyes.

Research is still ongoing to determine how white and coloured hairs are organized into the familiar spotting patterns, but here is the traditional view of how the two spotting patterns work.

Irish spotting varies from a little bit of white on the toes and/or chest all the way to a full blaze on the face, white chest, white neck collar and white on the legs and tail tip, but with no other white on the body. Almost all Nova Scotia Duck Tolling Retrievers are Irish spotted.

Splash white (also called particolour or piebald) in its minimal expression can look similar to an Irish spotted dog that has a little white on the neck. But in its maximum expression, a splash dog will be nearly all white with just a bit of colour left on the ears and/or around the eyes and/or at the base of tail. White Bull Terriers are splash white, as are most particolour Cocker Spaniels, English Springer Spaniels and many other spotted breeds. Some breeds carry both patterns.

Both Irish spotting and splash white can occur in combination with many other patterns. When it is found in conjunction with tan points, the pattern is called tricolour.

Brown and white German Shorthaired Pointer with splash white, ticking and roaning.

Dog Coat Colours That Change Over Time

Sometimes, dogs are born one colour or pattern and change as they get older, as previously described with the tan-point saddle pattern. Here are a few more.

Ticking causes spots to form on a white base coat. Pups are born white or white with coloured patches. The small spots gradually appear on the white parts of the coat as the puppy gets older. Ticking causes freckles and flecks of colour in many breeds, including Dalmatians, pointers, hounds and spaniels.

Roan causes white and coloured hairs to mix together instead of separating into spots. Like ticking, the roaned areas start out white and the coloured hairs gradually appear over time. This is very different from roan horses, which are born roan and stay that colour. Many dogs, such as Bluetick Coonhounds, English Setters, German Shorthaired Pointers roan Cocker Spaniels, are both ticked and roaned and may also have patches of colour. The cartoon dog Huckleberry Hound is painted blue because he is a bluetick hound.

There is another gene sometimes referred to as fading or greying. In the Kerry Blue Terrier and in silver, apricot and cream Poodles, the birth colour is dark, then gradually lightens to the adult colour. A silver Poodle and a Kerry Blue are both born black and have black noses, but the adult colour is silver to silver-blue of various shades. Apricot and cream Poodles are born some shade of red and then lighten with age. Other breeds that have this characteristic colour change include Bedlington Terriers, Old English Sheepdogs, Bearded Collies, Lowchens and several more. It seems to be confined to dogs with long coats.

Merles and Harlequins

A merle dog has part of the coat the regular colour and part of the coat diluted in a random series of patches, giving a sort of marbled appearance. Some dogs may be almost all the base colour with only a few flecks of the dilute colour, while others may be the opposite. Many Australian Shepherds are merle. The edges of merle patches generally appear torn or very irregular in shape, white different from the more symmetrical patches on a spotted dog. In Dachshunds, merle is referred to as dapple, but it is the same gene that causes the colour.

Merles often have eyes of different colours, or two light eyes, or even eyes that are half dark and half light.

In a double merle, both colours are lightened: for example, black becomes blue and blue becomes white. Double merles are often born deaf and/or blind and may die as puppies. Double merle can cause birth defects in puppies. Because of this, two merles should never to bred to reach other.

Merle is a dominant gene, which means that every merle dog must have one merle parent. It cannot just appear as a "hidden gene". Merle acts only on black, brown and fawn base colours, and does not affect red. Thus, a red merle is actually a brown dog with the merle gene. Tan markings on a tan-pointed merle will not be merle.

Since merle only affects black, brown and fawn, if combined with a dark mask, the mask can be merled; with brindle, the dark stripes will be merled; with saddle, the saddle marking will be merled; and with sable, the dark parts of the hair will be diluted, resulting in an unusual sable merle.

Harlequin is a colour found in Great Danes in which the spots are black and the rest of the coat is white. The spots have the same torn-edge appearance as merle spots, and sometimes a few of the spots will be blue. To be harlequin, the dog must carry both a single merle gene and a single harlequin gene.

Harlequins are seldom bred to each other for fear of producing double merle and/or double harlequin puppies, either of which are likely to die, have severe deformities or be born blind and and deaf. If a dog has the harlequin gene but not the merle gene, it will be a solid colour, because harlequin needs a merle gene for it to be expressed. Since in the absence of merle, harlequin can be carried without being seen, good breeders of Great Danes keep careful track of the colours in their dogs' pedigrees to avoid accidentally doubling up on merle and harlequin genes. Genetic testing has been a useful tool for this.

Merle plus harlequin or merle on its own also can be expressed on brindle, black and blue Great Danes, and on reds (called fawns in this breed) that carry a sable gene. These colours are considered very undesirable by good breeders because they are not included in the breed standard as correct Great Dane colours.

Correctly marked harlequin Great Dane

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Merle Great Dane, no harlequin gene (...

What Colour Is That Dog?

Different breeds use different names for colours, resulting in exotic descriptions like belton, grizzle, champagne, biscuit, apricot, lemon, wheaten, bronze, badger, mouse and wild boar. Unlike in horses, there has been no standard description for the various colours and combination of colours from one breed to the next.

Thus, a fawn Doberman refers to a dog that is a dilute brown, while a fawn Great Dane is a clear red. A red Doberman, a chocolate Labrador and a liver Field Spaniel are all brown. A buff Cocker Spaniel, a wheaten Scottish Terrier and a yellow Labrador are all red dogs with modifying genes that have lightened the coat colour.

However, a buff Nova Scotia Duck Tolling Retriever is a red dog with a dilution gene that lightens, not just the coat, but the nose and eyes as well. That same colour in a Chesapeake Bay Retriever is called dead grass.

For Further Reading

Here are some books that provide additional information about coat colour and its inheritance in dogs. The breed books listed here cover a variety of coat colours, since these breeds come in many colours and patterns.

Comments

I have just checked inheritance in Shelties. This breed has a recessive black gene, which in essence is agouti minus the modifying gene that allows red to show up, as in a normal sable red in other breeds. So the hairs, instead of being tipped in black, are entirely black. Thus it's not the same "black" as the regular dominant black/brown/grey gene. So a Sheltie carrying two genes for sable will always reproduce sable when bred to another Sheltie. However, that same Sheltie bred to a dog of another breed carrying the more common dominant black gene should produce some black puppies.

I've always been fascinated by coat color inheritance. I used to show Shetland Sheepdogs and in that breed, the sable color is dominant. A pure for sable will always have sable puppies no matter what they are bred to including black. How does that figure in with the other breeds?