Dog coat

thumb|350px|Coat variation of the dog

The coat of the domestic dog refers to the hair that covers its body. Dogs demonstrate a wide range of coat colors, patterns, textures, and lengths.

As with other mammals, a dog's fur has many uses, including thermoregulation and protection from cuts or scratches; furthermore, a dog's coat plays an important role in the showing of purebred dogs. Breed standards often include a detailed description of the nature and attributes of that breed's ideal coat.

A dog's coat is composed of two layers: a top coat of stiff guard hairs that help repel water and shield from dirt, and an undercoat of soft down hairs, to serve as insulation. Dogs with both under coat and top coat are said to have a double coat. Dogs with a single coat have a coat composed solely of guard hairs, with little or no downy undercoat.

The terms fur and hair are often used interchangeably when describing a dog's coat, however in general, a double coat, like that of the Newfoundland and most livestock guardian dogs, is referred to as a fur coat, while a single coat, like that of the Poodle, is referred to as a hair coat.

Genetics

thumb|A Labrador exhibiting a yellow coat colour

Domestic dogs exhibit diverse coat colours and patterns. In many mammals, different colour patterns are the result of the regulation of the Agouti gene, which can cause hair follicles to switch from making black or brown pigments to yellow or nearly white pigments. The most common coat pattern found in modern wolves is agouti, in which the upperside of the body has banded hairs and the underside exhibits lighter shading. The colour yellow is dominant to the colour black and is found in dogs across much of the world and the dingo in Australia. Research has found that tameness brings associated physical changes, including coat colouring and patterning.

Domestic dogs often display the remnants of countershading, a common natural camouflage pattern. The basic principle of countershading is when the animal is lit from above, shadows will be cast on the ventral side of the body. These shadows could provide a predator or prey with visual cues relating to the movement of the animal. By being lighter colored on the ventral side of the body, an animal can counteract this, and thereby fool the predator or prey. An alternative explanation is that the dorsal and ventral sides of an animal experience different selection pressures (from the need to blend into different backgrounds when viewed from above and below) resulting in differing coloration.

Nomenclature of colours and patterns

Colors

The same colour may be referred to differently in different breeds. Likewise, a same term may mean different colourations in different breeds.

Brown, chocolate, liver

Brown, chocolate and liver are the most common terms used to refer to the bb-dilution of black pigment to a dark brown. Depending on breed and exact shade, terms such as mahogany, midtone brown, grey-brown, blackish brown are used. Sedge and deadgrass are used to describe the desired Chesapeake Bay Retriever color that resembles "that of its working surroundings" as closely as possible.

File:Chesapeake Bay Retriever1.jpg|Brown Chesapeake Bay Retriever

File:Hilu the Australian Kelpie dog.jpg|Red Australian Kelpie

File:Chocolate Labrador Retrievers pair.jpg|Dark and light chocolate Labrador Retrievers

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Red

Red refers to reddish shades of orange, brown, and tan. Terms used include orange, red-gold, cinnamon, tan, and ruby. Genetically a dog called red is usually a clear sable (with little to no eumelanin tipping on hairs) or a ruddy recessive yellow.

In some breeds, "red" refers to what would usually be called brown, chocolate, or liver. A "red merle" is always a liver-based merle. In Australian Cattle Dogs, "red" stands for a densely ticked liver-based colouration with an overall red-grey appearance.

File:Seter irlandzki profil 5o899.jpg|Red Irish Setter

File:01 Chow Chow.jpg|Red Chow Chow

File:Owning the back step (3641313887).jpg|Red Standard Poodle

File:Ariel Cavalier King Charles Spaniel.jpg|Ruby Cavalier King Charles Spaniel

File:Australian Cattle Dog red.JPG|Red Australian Cattle Dog

File:A Shiba Inu.jpg|Red Shiba Inu

File:Basset Fauve de Bretagne portrait.jpg|Red Basset Fauve de Bretagne

File:Cocker spaniel angielski zlotyy.jpg|Red Cocker Spaniel

File:Vizsla-profile.jpg|Vizsla

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Gold and yellow

Gold refers specifically to a rich reddish-yellow and its variants, whereas yellow can refer to any shade of yellow and tan. Terms used include yellow-gold, lion-colored, fawn, apricot, wheaten, tawny, straw, yellow-red, mustard, sandy, honey, blond, and lemon. Dogs called golden or yellow tend to be recessive yellow, but can also be sable.

File:Agility Poodle.jpg|Apricot Poodle

File:3 Golden Retrievers in the water.jpg|Dark Golden Retrievers

File:Stretched Dachshund.jpg|Yellow Dachshund

File:YellowLabradorLooking.jpg|Yellow Labrador Retriever

File:Golden retriever.jpg|Dark Golden Golden Retriever

File:Milù 050.JPG|Orange Pomeranian (dog)

File:Zazu the dog on Lion's Head mountain 24.jpg|Yellow mixed breed of unknown parentage

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Cream

Cream refers to a pale yellowish or tannish colour which can be almost white.

File:Poodle, white standard 01.jpg|Pale cream Standard Poodle

File:FrenchBulldog.jpg|Cream French Bulldog

File:Yuki and Branca - Japanese Akita.jpg|Cream Akita

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Fawn

Fawn typically refers to a yellow, tan, light brown, or cream dog that has a dark melanistic mask.

With Weimaraners, fawn refers to their typical brownish grey colouration that with other breeds is usually called lilac.

File:Pug 600.jpg|Silver Fawn Pug

File:Westgort Anticipation.JPG|Fawn English Mastiff

File:Malinois puppy.JPG|Fawn Belgian Shepherd Malinois with breed-typical extended [dark] mask

File:Male fawn Boxer undocked.jpg|Fawn Boxer

File:HuntHillBoerboelsGunston1.jpeg|Fawn Boerboel

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Black

Black is a pure black that can get grizzled as the dog ages, or have a tendency to gain a brownish cast when exposed to the elements.

File:Newfoundland dog.jpg|Newfoundland

File:Black_labrador_on_green_grass.png|Elderly black Labrador Retriever with age-related grey hairs on head and feet

File:Schipperke image 001.jpg|Black Schipperke

File:Crni Patuljasti šnaucer.jpg|Black Schnauzer

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Blue

Blue is a cool-toned, metallic grey. It typically means a d/d dilution of black pigment, a grey colouration that is grey from birth, but has a wide range of breed-specific meanings.

In Kerry Blue Terriers, Poodles, and Bearded Collies, "blue" refers to colouration that is black at birth and progressively greys out as the dog matures. In Australian Shepherds, Rough Collies, and Shetland Sheepdogs, blue means a blue (black-based) merle. In Australian Silky Terriers, blue means a saddle-type black and tan pattern, where the black parts of the coat progressively fade to a steel grey as the dog matures and in Australian Cattle Dogs, blue stands for a densely ticked black-based colouration with an overall blue-grey appearance.

File:Standing_Neo.jpg|Blue Neapolitan Mastiff

File:PastorBelga-AlemaoDSC 2788.jpg|Blue mixed-breed dog

File:Australian Silky Terrier Karlyermai Classic Touch.jpg|Blue Australian Silky Terrier

File:Australian blue cattle dog 04.JPG|Blue Australian Cattle Dog

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Grey

Grey simply means a grey colouration of any shade. It can be used as an alternative synonym of blue, but tends to mean some other type of grey than the d/d dilution of black. Synonyms include silver, pepper, grizzle, slate, blue-black grey, black and silver, steel. Greys of a dusty or brownish cast are often lilac, a d/d dilution of liver, and this colouration does not have much of a commonly recognised name. Across various breeds, it is called lavender, silver-fawn, isabella, fawn, café au lait or silver beige.

In Poodles, a blue is a very slowly fading, very dark steel grey, whereas a silver is a quicker to clear, much lighter grey that can range from a pale platinum to a steel grey. Both are black at birth with minimal markings to indicate future change. Similarly, café au lait is a slower and darker and silver beige a quicker and lighter progressively greying brown, i.e. liver.

File:Waterloo 027 4x6.JPG|Lighter and darker fawn Weimaraners

File:Miniature Schnauzer 2.jpg|Silver Miniature Schnauzer

File:Spooky (8359203146).jpg|Young Silver Standard Poodle in the earliest stages of graying out

File:Doberman Fawn 001.jpg|Isabella/fawn Dobermann

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White

White: Such a light cream that it is seen and described as pure white, making them distinct from albino dogs. A white dog, as opposed to an albino one, has dark pigment around the eye rims and nose, often coupled with dark-colored eyes. There is often some coat identifiable as cream between the dog's shoulder blades. Extreme piebald dogs can also appear all white, but are caused by a separate factor.

File:American Eskimo Dog.jpg|White American Eskimo Dog

File:Bichon Frise 600.jpg|White Bichon Frisé

File:Maltese at NZ National Dog Show.jpg|White Maltese dog

File:Coton de Tulear puppy.jpg|White Coton de Tulear puppy

File:Bruno spitz japones.jpg|White Japanese Spitz

File:Samoyed Image 001.jpg|Samoyed dog

File:Westhighlandterrier.jpg|West Highland White Terrier

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Patterns

The same pattern may be referred to differently in different breeds.

{| class=wikitable

|align=center|100x100px Black and Tan Dachshund

|align=center|110x110px Black and tan Miniature Pinscher

|Black and tan, liver and tan, blue and tan: Coat has both colors but in clearly defined and separated areas, usually with the darker color on most of the body and tan (reddish variants) underneath and in highlights such as the eyebrows. Black and brindle and liver and brindle, in which the same pattern is evident with brindling in place of tan, are also possible, but less common.

|align=center| 100px Black and white Border Collie

|align=center| 100px Blenheim (Red-brown and white) Cavalier King Charles Spaniel

|Piebald or pied (also called bicolor, tricolor, Irish spotted, Flashy, Patched, Tuxedo): any color or pattern coupled with white spotting. This can range anywhere from white toes and tail tip to a mostly white dog with color around the base of the ears and tail. Some breeds have special names for the color combinations; for example, Cavalier King Charles Spaniel uses Blenheim for reddish brown (chestnut) and white. Irish Spotted or flashy pattern is symmetrical and includes a white chest, white band around the neck, white belly, and white feet or "boots". This pattern is commonly seen in herding dogs, and Boxers, among others. The piebald gene is responsible for this pattern.

|align=center| 100px Extreme piebald Borzoi with small colored patches

|align=center| 100px Piebald white Dogo Argentino

|Extreme piebald or piebald white: an extensive piebald pattern that renders the dog mostly or all white with pink skin. Usually some pigmented specks remain. Governed by the piebald gene.

|align=center|109x109px Tricolor

Basset Hound

|align=center|100px Tricolor Beagle

|Tricolor: Three clearly defined colors, usually either black, liver, or blue on the dog's upper parts, white underneath, with a tan border between and tan highlights; for example, the Smooth Collie, the Rough Collie, the Papillon, or the Sheltie. Tricolor can also refer to a dog whose coat is patched, usually two colors (such as black and tan) on a white background.

|align=center| 100px Blue merle tricolor Shetland Sheepdog

|align=center| 100px Red merle Catahoula Leopard Dogs

|Merle: Marbled coat with darker patches and spots of the specified color. Merle is referred to as "Dapple" in Dachshunds.

|align=center |100px Tuxedo Lab mix.

|align=center| 85px Tuxedo Collie mix

|Tuxedo: Solid (often black) with a white patch (shirt front) on the chest and chin, and white on some or all of the feet (spats.) Named after the tuxedo dinner suit, the pattern is common in dogs that carry only one piebald gene (a heterozygous carrier).

|align=center |100px Harlequin Great Dane

|Harlequin: "ripped" splotches of black on white. The Great Dane is the only breed with this pattern. The term harlequin is also sometimes used to describe a piebald spotting pattern, such as parti-colored poodles.

|align=center|100px Spotted Dalmatian

|align=center |100px Spotted mutt in Sinamaica, Venezuela

|Spotted Coin-sized pigmented spots on a white background. The spotting on Dalmatians is unique as it involves mutations in at least three different spotting genes.

|align=center|100px Red-speckled Australian Cattle Dog

|align=center|100px Liver-ticked German Shorthaired Pointer

|rowspan=2|Flecked, ticked, speckled: also called belton in English Setters

|align=center| 100px Orange belton (orange and white speckled) English Setter

|align=center| 100px Blue speckled Australian Cattle Dog

|align=center|100x100px Brown brindle and white Boxer

|align=center| 100px Very sparsely brindled Great Dane

|Brindle: A mixture of black/liver/blue/lilac and red/yellow/cream arranged in a vertical "tiger stripe" pattern.

|align=center| 100px Airedale Terrier with large black saddle

|align=center| 100px Norwegian Dunker with merle-affected black saddle

|Saddle or blanket: A different color, usually darker, over the centre of the back.

|align=center|100px Dark orange sable Pomeranian

|align=center|131x131px Sable Pembroke Welsh Corgi

|Sable: Black-tipped hairs overlaid onto a different coloured, lighter background, including grey, silver and gold.

|center|135x135pxHairless Chinese Crested Dog

|center|150px Xoloitzcuintle

|Hairless: Some dogs are born without a fur coat.

Length and texture

Dogs demonstrate an enormous diversity in coat length and texture, from the very short and smooth coat seen in the vizslas, to the wiry coat of a Scottish Terrier and the corded coat of the Puli and the Komondor.

Generally, coats vary along three categories: length (long vs. short), texture (curly vs. straight), and coarseness (wire-haired vs. non-wire). These three categories all interact with one another; thus, one can see a short, curly, and wired coat in the Wirehaired Pointing Griffon, and a long, straight, and non-wired coat in the Pomeranian.

Additionally, breeds show variation in patterns of growth - that is to say, parts of the dog's body where the coat may be longer or shorter. The same gene that controls wiriness of hair also causes furnishings to be present (e.g. beard, moustache, eyebrows) Among the other coat types, dogs with fine silky coats (e.g., spaniels) are generally moderate shedders, those with an intermediate coat texture (e.g., mountain dogs) are generally heavy shedders, and those with thick stand-offish coats (e.g., spitzes) are generally very heavy shedders.

thumb|The [[Portuguese Water Dog is an example of a breed with single, low-shedding coat.]]

"Non-shedding" dogs have greatly-reduced shedding due to alterations to the hair follicle growth cycle:

homozygosity for the furnishings (wire) allele - Most breeds with facial furnishings (including ones whose faces are usually shaved removing the furnishings) are low-shedding, but they must be homozygous, so dogs of mixed wire/non-wire parentage (e.g., terrier crosses or breeds with wire and non-wire varieties) can be heavy shedders. There are a few furnished breeds that shed more (e.g., Old English Sheepdog, Bearded Collie, Briard, Otterhound);
at least one copy of the single-coat (non-shedding) allele - Most dogs with a smooth coat are low shedding, as well as the fringed or flat coat. There are breeds with a very short coat that shed more (e.g., Basset Hound, English Bulldog, Pug, Toy Fox Terrier, Dalmatian, Vizsla, German Shorthaired Pointer);
single coat (no undercoat) plus furnishings (homozygous) - These breeds shed the least (e.g., Poodle, Soft-coated Wheaten Terrier).

Hypoallergenic coat

"[D]ogs are a relevant source of allergens, but diagnosing dog-related allergies may present difficulties ..." Some dog breeds have been promoted as hypoallergenic (which means less allergic, not free of allergens) because they shed very little. However, no canine is known to be completely nonallergenic. Often the problem is with the dog's saliva or dander, not the fur. Although breeds such as poodles, Bedlington terriers, bichons, yorkies, and wire-haired terriers are commonly represented as being hypoallergenic due to reduced shedding, the reaction that an individual person has to an individual dog may vary greatly. In a report, describing dog allergen extracts of dog hair, belonging to patients' dogs or from dogs of the same breed, with low molecular mass that are absent in extracts of commercial allergen test kits, it has been found that "[f]actors related to individual dogs seem to influence the allergenicity more than breed or gender." For this reason, coat health is an important aspect of pet care to many dog owners. Below is a table that summarizes the effects of several nutrients (minerals, vitamins) on the domestic canine coat, based on current evidence:

{| class="wikitable"

! Nutrient

! Role

! Impacts when deficient

! Benefits

| Zinc

| Gives strength to collagen

| Dry and brittle coat

| Brittle fur, hypo-pigmentation, discoloration

| Sparse coat growth

| Rough coat

| Alopecia and achromotrichia beginning at the root of the coat Dogs can obtain zinc in their diet, through the addition of various ingredients, including; red meats, whole grains, poultry by-product meals, and fish meals.

Copper

Copper is a trace mineral that is required in the diet of canines at 7.3 mg/kg. Copper is involved in multiple enzymatic pathways. In dogs, a lack of copper in the diet, leading to a copper deficiency, results in incomplete keratinization. Lack of selenium in the diet of a dog can contribute to the occurrence of sparse coat growth. Dogs can obtain selenium in their diet through the addition of various ingredients including; tuna fish, halibut, sardines, beef, chicken, and egg.

Vitamins

Vitamin A

Vitamin A deficiency can lead to rough coat, scaling of skin, and other dermatitis issues like alopecia.

Vitamin B7 (Biotin)

Vitamin B7, also known as biotin, is a water-soluble nutrient that is known to play a role associated with the maintenance and development of hair starting from the follicle. Although it has not been clinically shown to improve hair growth with supplementation alone, it has been shown to reverse deficiency in dogs born deficient.

Symptoms of biotin deficiency include alopecia and achromotrichia. A clinical study of biotin showed the importance of biotin in coat pigmentation. There different stages of hair development, as shown in clinical studies using mice.

The proper combination of these omega fatty acids is crucial to achieve optimal benefits. Proper omega 6:3 ratios have been shown to diminish allergy triggered immune responses, thus improving overall coat condition. The National Research Council (NRC) recommends a 2.6:1 to 26:1 omega 6:3 ratio for adult dog maintenance diets. The proper ratio of these fatty acids is crucial because each has an opposing role in inflammation within the body and both compete for the same enzymatic pathway. The specific role of vitamins A and E for coat health are explored elsewhere in this article, as they pertain to immune function. DHA acts even earlier in omega 6 metabolism, by inhibiting delta-6-desaturase.

Genetics

Nomenclature of colours and patterns

Colors

Brown, chocolate, liver

Red

Gold and yellow

Cream

Fawn

Black

Blue

Grey

White

Patterns

Length and texture

Hypoallergenic coat

Copper

Vitamins

Vitamin A

Vitamin B7 (Biotin)

Further reading

External links