A melanistic mask (also referred to as a mask or masking) is a

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 fur has many uses, including thermoregulation and protection f ...

pattern that gives the appearance of a

mask A mask is an object normally worn on the face, typically for protection, disguise, performance, or entertainment and often they have been employed for rituals and rights. Masks have been used since antiquity for both ceremonial and pra ...

on the dog's face. The hairs on the muzzle, and sometimes entire face or ears, are colored by eumelanin instead of

pheomelanin Melanin (; from el, μέλας, melas, black, dark) is a broad term for a group of natural pigments found in most organisms. Eumelanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the a ...

pigment. Eumelanin is typically black, but may instead be brown, dark gray, or light gray-brown. Pheomelanin ranges in color from pale cream to mahogany. The trait is caused by M264V (''E^M''), a completely dominant

allele An allele (, ; ; modern formation from Greek ἄλλος ''állos'', "other") is a variation of the same sequence of nucleotides at the same place on a long DNA molecule, as described in leading textbooks on genetics and evolution. ::"The chro ...

(form) of the

melanocortin 1 receptor The melanocortin 1 receptor (MC1R), also known as melanocyte-stimulating hormone receptor (MSHR), melanin-activating peptide receptor, or melanotropin receptor, is a G protein–coupled receptor that binds to a class of pituitary peptide hormones ...

gene In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...

Appearance

At minimum, a melanistic mask will appear on the muzzle, and may also be visible on the eartips, entire ears, or entire face. Hairs in those areas will be colored by eumelanin instead of pheomelanin pigment, making it look as though the dog has a mask on its face. Eumelanin is usually black, but may instead be liver (also known as chocolate; dark brown), blue (also known as slate; dark grey), or isabella (also known as lilac; light grey-brown); accordingly, a mask may be any of these colors. Pheomelanin occurs in shades of red ranging from ivory to mahogany, which include cream, gold, and tan. A mask is visible in conjunction with a variety of coat patterns, such as tan points and sable. Nonetheless, it may be difficult to see with certain others, such as

brindle Brindle is a coat coloring pattern in animals, particularly dogs, cattle, guinea pigs, cats, and, rarely, horses. It is sometimes described as "tiger-striped", although the brindle pattern is more subtle than that of a tiger's coat. Brindle ty ...

, and will not be visible on a completely eumelanic coat. Any white markings on the coat, caused by a lack of pigment, will appear to be layered over the mask and other markings.

Genetic basis

The melanistic mask is caused by the M264V allele (known as ''E^M'') at the

(MC1R)

locus Locus (plural loci) is Latin for "place". It may refer to: Entertainment * Locus (comics), a Marvel Comics mutant villainess, a member of the Mutant Liberation Front * ''Locus'' (magazine), science fiction and fantasy magazine ** ''Locus Award' ...

, also known as the ''extension locus''. It is completely dominant to the other alleles of the gene, and causes the

melanocyte-stimulating hormone The melanocyte-stimulating hormones, known collectively as MSH, also known as melanotropins or intermedins, are a family of peptide hormones and neuropeptides consisting of α-melanocyte-stimulating hormone (α-MSH), β-melanocyte-stimulating ...

to bind to and activate melanocortin 1 receptors (located on melanocytes) in the mask's area, causing those melanocytes to produce eumelanin. Another allele, known as ''E'', is responsible for "normal extension", which allows eumelanin to be produced as usual. ''e'', completely recessive to the other alleles, suppresses all eumelanin production in the coat—the resulting color is sometimes known as ''recessive red'', ''clear red'' or ''Australian red''. Therefore, if a dog appears clear red or fawn but has a mask, the

agouti gene Agouti-signaling protein is a protein that in humans is encoded by the ASIP gene. It is responsible for the distribution of melanin pigment in mammals. Agouti interacts with the melanocortin 1 receptor to determine whether the melanocyte (pigment ...

is responsible for all pheomelanic hairs. Although

Clarence Cook Little Clarence Cook Little (October 6, 1888 – December 22, 1971) was an American genetics, cancer, and tobacco researcher and academic administrator, as well as a eugenicist. Early life C. C. Little was born in Brookline, Massachusetts and atte ...

proposed in 1957 that

was caused by another allele at the same locus, known as ''e^br'', his hypothesis was refuted in a 2007 study.

Gallery

File:Deutscher Schäferhund- portrait.JPG, German Shepherd dog with black mask File:Whippet długowłosy głowa suki MB 01.jpg, Longhaired

whippet The Whippet is a dog breed of medium size. It is a sighthound breed that originated in England, descended from the Greyhound. Whippets today still strongly resemble a smaller Greyhound. Part of the hound group, Whippets have relatively few ...

with black mask File:French Mastiff 001.jpg, Red

dogue de Bordeaux The Dogue de Bordeaux, Bordeaux Mastiff, French Mastiff or Bordeauxdog is a large French mastiff breed. A typical brachycephalic mastiff breed, the Bordeaux is a very powerful dog, with a very muscular body. This muscular breed has been put to ...

with liver mask File:AlpineMastiff0077.JPG, St. Bernard with black mask and white markings File:Kerry blue terrier pl2.jpg,

Kerry blue terrier The Kerry Blue Terrier (also known as the Irish Blue Terrier) ( gle, An Brocaire Gorm) is a breed of dog. Originally bred to control vermin including rats, rabbits, badgers, foxes, otters and hares, over time the Kerry became a general working d ...

with black mask. Although the coat on the body has lightened in color in a process known as "clearing" or "greying", the mask has retained its original color. File:Vilda1.jpg,

Border collie The Border Collie is a Scottish breed of herding dog of medium size. Widely considered to be the most intelligent dog breed, they are descended from landrace sheepdogs once found all over the British Isles, but became standardised in the Ang ...

puppy with black mask, tan points, and white markings. On the front portion of the muzzle, the points on the cheeks are partially "covered up", or inhibited in expression, by the mask.

References

{{reflist Dog anatomy Animal hair Animal coat colors