Dog coat
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
A dog's coat is composed of two layers: a top coat of stiff
The terms
Genetics
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.[2]
In 2021, a study of whole genome sequences taken from dogs and wolves focused on the genetic relationships between them based on coat colour. The study found that most dog colour
During evolution of the dog from their wolf ancestors, coat colors in dogs were probably the inadvertent outcome of some other selective process, and were not likely initially selected for intentionally by humans.[3] Research has found that tameness brings associated physical changes, including coat colouring and patterning.[4]
Domestic dogs often display the remnants of
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.
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Brown Chesapeake Bay Retriever
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Dark and light chocolateLabrador Retrievers
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, "blue" stands for a densely ticked liver-based colouration with an overall red-grey appearance.
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Red Irish Setter
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Red Chow Chow
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Red Standard Poodle
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Red Australian Cattle Dog
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Red Shiba Inu
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Red Cocker Spaniel
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.
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Apricot Poodle
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Dark Golden Retrievers
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Yellow Dachshund
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Yellow Labrador Retriever
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Dark Golden Golden Retriever
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OrangePomeranian (dog)
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Yellow mixed breed of unknown parentage.
Cream
Cream refers to a pale yellowish or tannish colour which can be almost white.
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Pale cream Standard Poodle
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Cream French Bulldog
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CreamAkita
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.
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Silver Fawn Pug
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Fawn English Mastiff
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FawnBelgian Shepherd Malinoiswith breed-typical extended [dark] mask
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FawnBoxer
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Fawn Boerboel
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.
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Newfoundland
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Elderly black Labrador Retriever with age-related grey hairs on head and feet
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Black Schipperke
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Black Schnauzer
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
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Blue Neapolitan Mastiff
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Bluemixed-breed dog
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Blue Australian Cattle Dog
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.
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Lighter and darker fawn Weimaraners
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Silver Miniature Schnauzer
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Young Silver Standard Poodle in the earliest stages of graying out.
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Isabella/fawn Dobermann
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.
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White American Eskimo Dog
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White Bichon Frisé
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White Maltese dog
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White Coton de Tulear puppy
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White Japanese Spitz
Patterns
The same pattern may be referred to differently in different breeds.
Black and Tan Dachshund |
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. |
Black and white Border Collie |
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, Boxers, among others. The piebald gene is responsible for this pattern.
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Extreme piebald Borzoi with small colored patches |
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. |
Tricolor |
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 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.
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Blue merle tricolor Shetland Sheepdog |
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.
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mix .
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mix
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heterozygous carrier).
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Harlequin Great Dane |
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. |
Dalmatian
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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.[6] |
Red-speckled Australian Cattle Dog |
Liver-ticked German Shorthaired Pointer |
Flecked, ticked, speckled: also called belton in English Setters |
Orange belton (orange and white speckled) English Setter |
Blue speckled Australian Cattle Dog | |
Boxer
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Very sparsely brindled Great Dane |
Brindle: A mixture of black/liver/blue/lilac and red/yellow/cream arranged in a vertical "tiger stripe" pattern. |
Airedale Terrier with large black saddle |
Norwegian Dunker with merle-affected black saddle |
Saddle or blanket: A different color, usually darker, over the centre of the back. |
Pomeranian
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Sable Pembroke Welsh Corgi |
Sable: Black-tipped hairs overlaid onto a different coloured, lighter background, including grey, silver and gold.[7] |
Hairless Chinese Crested Dog | 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
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) [8] - compare the bearded collie, furnishings present, to the border collie, which lacks furnishings. Some breeds show feathering: fringes of longer hair on the ears, belly, tail, and back of the legs (e.g., Saluki and any of the setters).
Dogs also vary in the thickness of the undercoat. Some dogs have only a single (rather than a double) coat, or a very reduced undercoat (e.g. the Vizsla), which results in a thinner coat. Certain breeds, especially spitz-type breeds, tend to have a thicker undercoat, which helps retain heat in cold and wet weather.
Furthermore, complete hairlessness on parts of the body is present in breeds such as the
Shedding
Shedding of hair can occur continuously, but in many breeds is strongly influenced by hormones. Seasonal shedders shed most in spring and fall, following an increase or decrease in day length, and least in summer and winter, in response to constant day length. Cold temperatures stimulate hair growth, so that the heaviest shedding is in spring on dogs living in cold climates. Artificial lighting can alter the seasonal shedding pattern of dogs who live indoors. Other hormonal influences include dietary factors, reproductive hormones in intact dogs, and various medical conditions and disorders. Shedding that is done in a short period of time is known as "blowing the coat" or "blowing coat".[9][10] 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.
"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 .."
Show coats
The nature and quality of a
Nutritional impacts on coat
A dog's coat is an outward indicator of internal well-being.[13] For this reason, coat health is an important aspect of pet care to many dog owners.[13] Dog coats can be impacted by nutritional components from the diet.[14] Below is a table that summarizes the effects of several nutrients (minerals, vitamins) on the domestic canine coat, based on current evidence:
Nutrient | Role | Impacts when deficient | Benefits |
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Zinc | Gives strength to collagen[15] | Dry and brittle coat[15] | Contributes to coat growth and prevents brittle and dry coat[15] |
Copper | Involved in keratinization[16] | Brittle fur, hypo-pigmentation, discoloration[16] | Improved color and keratinization[16] |
Selenium | Cell growth; antioxidant[17][18] | Sparse coat growth[17] | Coat growth promotion[18] |
Vitamin A | Proliferation of keratinocytes[19] | Rough coat[19] | Proliferation of keratinocytes; hair follicle growth[20][19] |
Biotin | Saturation of Coat[21] | Alopecia and achromotrichia beginning at the root of the coat[21] | Contributes to coat shine, thickness/distribution of hair follicles[21] |
Trace minerals
Zinc
Zinc contributes to hair growth and can prevent hair from becoming dry and brittle.[15] In addition to, zinc when supplemented in combination with linoleic acids has been found to improve the coat of canines by reducing water loss in the trans-epidermal layer of the skin.[22] 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.[23] 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.[16] This leads to a dry coat, hypo-pigmentation, and discoloration of the coat.[16]
Selenium
Selenium is another one of the many trace minerals essential for a dog's diet. Selenium is typically required in lower levels in comparison to other minerals. It is involved in the prevention of oxidative damage as well as the production of anti-oxidants.[17] Selenium aids in the promotion of coat growth.[24] Lack of selenium in the diet of a dog can contribute to the occurrence of sparse coat growth.[25] 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 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.[27]
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.[21] Each stage of hair development has a different sensitivity to biotin present in the body. For example, the shaft development is not greatly affected by biotin access.[21] During the last stage, the amount of biotin available for use by the body will alter the success of that development greatly.[21] Throughout the hair development, most stages of growth are completed, but it was found that in the last stage, where biotin levels were insufficient, there was an incorrect keratinization of the root of the hair, causing the hair to fall out of the body.[21]
The supplementation of biotin cannot reverse affects caused by deficiency, but as soon as supplementation is given and biotin levels are restored to adequacy, the body begins to produce the usual hair growth and color it would before the deficiency took place.[21]
Essential fatty acids
Polyunsaturated fatty acids found in the diet play a critical role in the maintenance of a healthy coat in dogs, and have even been shown to improve coat condition when supplemented in the diet.[14] Furthermore, diets lacking essential fatty acids in their diet will manifest as unkept, matted coat.[13] Omega fatty acids 3 and 6 are highly unsaturated fatty acids, making them especially metabolically active.[28]
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.
Aside from omega fatty acids, lipid content in the canine diet is an important aspect of coat health.
Omega 3 (linolenic acid)
Omega 3 fatty acid, also known as
Omega 6 (linoleic acid)
Omega 6 fatty acid, also known as linoleic acid, is found in poultry fat and the oil from safflower, sunflower, corn and flaxseed.[29] Arachidonic acid is a well known metabolic derivative of linoleic acid, found only in animal sources.[29] As mentioned above, arachindonic acid is a pro-inflammatory compound.[32] It is critical to note once again that canines are unable to interconvert between omega fatty acids and over supplying linoleic acid promotes excessive inflammation in the body, which can potentially reverse the coat benefits seen by supplying omega fatty acids in the diet. In contrast, linoleic acid is also required for epidermal lipid function and water retention, which benefits coat shine.[22][29] Having linoleic acid present in the diet has demonstrated a positive effect on skin, and thus by extension, coat.[13]
See also
- Chiengora
- Dog grooming
- Dog skin disorders
- Hypoallergenic
- List of dog breeds
- Merle (coat color in dogs)
References
- ^ "How to Keep Your Dog Warm This Winter". Spoiled Pets Shop. 2014. Retrieved November 10, 2014.
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- ISBN 978-1440512148. Retrieved 2017-07-04.
- ISBN 978-1593788391. Retrieved 2017-07-04.
- ^ S2CID 37091773.
- ^ Grady, Denise (February 5, 1997). "Nonallergenic Dog? Not Really". New York Times. Retrieved April 3, 2011.
- ^ PMID 17542730.
- ^ PMID 9868266.
- ^ PMID 20620758.
- ^ a b c d e Tewari, Singh, Gautam, Dwivedi (December 2013). "Nutritional dermatosis - a review". Intas Polivet. 14: 199–202 – via GALE.
{{cite journal}}
: CS1 maint: multiple names: authors list (link) - ^ PMID 28243487.
- ^ S2CID 23201891.
- ^ a b c d e Baviskar, Jayanthy & Nagarajan (2013). "Vitamin - a responsive dermatosis in a dog". Intas Polivet. 14: 210.
- ^ PMID 21827690.
- ^ S2CID 87665589.
- ^ .
- ^ a b c "The Association of American Feed Control Officials > Publications". www.aafco.org. Retrieved 2017-11-28.
- PMID 24485058.
- PMID 20805887.
- ^ Beigh, S.A; Soodan, J.S; Bhat, A.M; Singh, V; Tantary, H (2013). "Clinical diagnosis and management of vitamin--a responsive canine dermatosis". Intas Polivet. 14 (2): 207–210.
- PMID 19727438.
- ^ PMID 23984423.
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Further reading
- Fogle, Bruce (2000). "The Breed Section Explained". The New Encyclopedia of the Dog. Dorling Kindersley. p. 83 and various. ISBN 978-0-7513-0471-8.
External links
- Schmutz, Sheila M. (March 4, 2010). "Dog Coat Color Genetics". University of Saskatchewan. Retrieved September 12, 2010.