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Coat Color Inheritance in the Anatolian Shepherd Dog

by Mary M. Ewald

Article from Choban Chatter, Vol 3, No. 1 & 2, Winter/Spring 1993. Preface by author: This paper was written  as a requirement for a genetics course that I was taking. It is a student's treatise on the subject, and should be read as such. However, having said all of that, I believe that the information will be useful to anyone trying to predetermine the colors of the puppies they produce, and helps to explain why certain colors, such as white, may be produced from dark dogs.

The Anatolian Shepherd dog is a livestock guarding dog with origins in Turkey. They are being used extensively across North America to protect flocks of sheep, goats, and rare species against coyote, bear and other predators.

Exact origins of the breed are unknown, but apparent progenitors have been depicted in Assyrian bas relief's dating from 2000 B.C. Roman war dogs of Molossian (Mastiff) type were probably left behind after invasion of Turkey to intermingle with native dogs. There is also strong evidence of a link with other European livestock guarding breeds such as the Maremma-Abruzze, Komondor, Kuvasz, Caucausian Ovtcharka and Shar Planinetz -- all of which evolved from the Tibetan Mastiff.

Modern Turkish shepherds choose dogs based on ability, with little regard to color, but there appears to have been a time when dogs were bred to match the color of their charges so that they would blend in and deceive predators. Localized regions in Turkey exist where certain colors are more often found, but an increased mobility of the people has led to a blending of these gene pools; some very interesting color patterns have emerged.

Coat color in the dog is inherited through somatic cells and there is no evidence of linkage of coat color genes. Four loci which may contain any of four alleles, and six loci that may contain two alleles each have been identified. Epistasis appears to be very common in a system that involves many types of dominant and recessive alleles. Incomplete dominance is often expressed. Color mutations are rarely observed, but can never be ruled out.

There are two major types of pigment in dog coats. These are yellow and dark (black or brown). All color variations arise from combinations of genes utilizing these pigments. Melanin, the actual pigment in the coat, is formed by the interaction of a chromogen or "color base" and an enzyme. The pigment is distributed to varying degrees in either or both the cortex (outer layer) or the medulla (inner layer) of the hair giving different color effects.

The ten categories of genes involved in canine coat color currently identified are as follows.

1.  A series
These genes form a series of multiple alleles at the A locus which influence the location of dark and light pigment on the individual hair and coat. There are at least five alleles in this group. The A+ allele produces the agouti or wild-type color of banded hairs seen in some wild canines and the Anatolian Shepherd.
 
2.  B-b pair.
B gene produces black color, recessive bb produces liver or chocolate brown color.
 
3.  C series.
C is the gene for full depth of pigment. Two recessive c alleles code for complete albinism and extreme dilution. The cch reduces the red-yellow pigment without effect on the black pigment of skin.
 
4.  D-d pair.
D dogs are densely pigmented, and is observed in most dogs. The genes dd produce a diluted or blue phenotype which has been observed in the Anatolian.
 
5.  E series.
Em (according to Clarence Little) is responsible for the black mask observed in the Anatolian and several other breeds, and it may be epistatic to other members of the E series. E allows for the formation of dark pigment evenly throughout the entire coat. The genes ee produce hairs with no dark pigment so that it is an evenly distributed shade of red or yellow. The gene ebr for brindle is epistatic to e, but incompletely hypostatic to E. The presence of alleles of A are necessary for expression of the brindle (striped) pattern.
 
6.  G-g pair.
The gene G is responsible for the lightening with age of puppies born dark in color. Dogs that show no lightening are gg in makeup.
 
7.  M-m pair.
Uniform pigmentation is mm. A heterozygous genotype will produce mere (dapple) coloration. Those with a makeup of MM are often severely deformed or handicapped.
 
8.  P-p pair.
Homozygous recessive expression is to greatly reduce the dark pigment of the coat without changing the red-yellow pigment.
 
9.  S series.
There are at least four alleles in this group. The S gene codes for a solid colored dog with virtually no white on it. The recessives of this series code for varying amounts of spotting or "piebald" expression as seen in the Anatolian.
 
10. T-t pair.
The gene T is dominant and codes for flecks or ticks of color on a white background. It is currently felt that more than two alleles are involved in the expression of ticking.

In 1989, Roy Robinson of England published a paper in Genetica on Anatolian Shepherd Dog coat color inheritance. His data were drawn from extensive records maintained by breed clubs in the United States and England. His results have helped to clarify the many phenotypical expressions of color observed by breeders and enthusiasts, but he did not deal with all coloration's that have been observed. In addition, he cites the occurrence of a "single blue diluted dog . . . bred from normal fawn parents." This dog was from one of my litters and also had a blue littermate. One parent was fawn with a black mask and the other was white. The fawn parent came from a line that has produced several "dilute" offspring. Robinson's conclusions that the blue expression was a result of a dd genotype is probably still correct, but he makes the assumption that both parents were heterozygous for this trait. The white dam never produced any dilute offspring when bred to different males, and the dilutes produced by the sibling of the male were sired by males totally unrelated to the white female. My personal belief is that the dilute coloration's of slate blue with a grey mask and light liver with a liver mask are a result of epistasis or a rare polygenic combination. There have been only seven dogs of these phenotypes reported out of over 3500 dogs registered, and more than half of these came from one line.

Robinson reports that the fawn color (with black mask) most often observed in Anatolian Shepherd Dogs is produced by the dominant yellow allele Ay which is dominant to the wild-type allele for wolf-grey coloring, A+ of the agouti series. Many of the dogs of this breed also have white markings on the face, legs, chest and belly which are inherited as a recessive to the non-white. The white pattern is attributable to Ay allele for which piebald has great variations in expression. The dogs vary from fawn with white paws to white with fawn patches.

The Anatolian Shepherds, sometimes called Akbash that are referred to as white are in fact genotypically cream. The white color is inherited as recessive to fawn with the allele cch (chinchilla) degrading the yellow pigment to cream or white, while leaving the skin and nose black. White puppies are often born with faint piebald markings or patches which fade with age. The reverse is also true with white puppies turning fawn with age.

Robinson disagrees with Little on the inheritance of the facial mask. He believes that the mask is a polygenic trait, while Little reports that it is a monogenic result of the gene Em.

Robinson's report does not deal with the genotype for brindles or blacks that I observed in Turkey, nor does he mention the ticking that is so often found in the white patches of the neck and legs. In fact, during a recent trip to Turkey, I observed a brindle extreme piebald male with ticking over his entire body.

Robinson's results were as follows:

[ Genetics Chart ]

The occurrence of brindle coloration in the Anatolian Shepherd Dogs is relatively rare in the United States. Little reports that a monozygous ebr codes for this pattern and that it is epistatic to e and incompletely hypostatic to E and requires the presence of the Ay gene. This claim seems to be supported by the observations in the Anatolian Shepherd Dog. All brindle dogs that have been bred to totally unrelated Ay__ dogs have produced litters that are close to 50% brindle.

The black Anatolians that have been observed in Turkey may be a phenotypic expression of a very dark brindle with or without a homozygous BB pair of alleles to code for black. There is no information currently available on the pedigrees of black dogs. The possibility also exists that these are not purebred dogs, however, the Tibetan Mastiff--an Anatolian ancestor--commonly exhibits a black coat.

Overall body ticking in two brindle piebald siblings is probably due to inbreeding of dogs carrying the T allele. Leg ticking is often observed, but body ticking is not.

Because this is primarily a working breed of dog, little attention should be paid to color, and far more to soundness and temperament. it is probably optimistic to expect all breeders to feel this way and already there is a certain prejudice towards fawn dogs by both breeders and judges. One of the reasons for this is lack of understanding the genetics of coat color that leads to the great diversity and almost unlimited combinations observed.

The Inheritance of Coat Length

Crawford and Loomis reported on the inheritance of short or long coat in another Molossian-type breed, the St. Bernard. They concluded that inheritance is based on simple autosomal inheritance of the dominant (short coat) or recessive (long coat) alleles.

The Anatolian Shepherd Dog shows the same mode of inheritance for coat length. Short coated dogs can produce long coats, but long coated dogs never produce short coats. The amount of feathering on the legs, density of the coat and length of the mane do not appear to be directly related to the length of coat except in a slightly proportional manner. Short coated dogs can have heavy feathering, and long coated dogs may have less. This leads me to suppose that the other coat characteristics are on separate chromosomes.


Bibliography:

Crawford, R.D. and Glenda Loomis, Inheritance of short coat and long coat in St. Bernard dogs, The Journal of Heredity, 69:266-267, 1978.

Hart, Earnest H., Encyclopedia of Dog Breeds, TFH Publications, Inc., Great Britain, 1975.

Little, Clarence C., The Inheritance of Coat Color in Dogs, Howell Book House, New York, 1967.

Robinson, Roy, Inheritance of coat colour in the Anatolian Shepherd dog, Genetica 79: 143-145, 1989.

Willis, Malcolm B., Genetics of the Dog, Howell Book House, New York, 1989.


Definitions

Allele
Any of a series of two or more genes that can appear at the same position or locus on a chromosome.
Epistasis (and Hypostasis)
A form of gene interaction whereby one gene masks or interferes with the phenotypic expression of one or more genes at other loci. The gene whose phenotype is expressed is called epistatic, that gene whose expression is suppressed is hypostatic.
Gene
The functional unit of heredity found on the chromosomes and consisting of DNA.
Heterozygous
When different allelic genes are present at one or more paired loci in homologous chromosomes.
Homologous
Chromosomes or chromosome parts identical with respect to their genetic loci.
Homozygous
When identical genes are present at one or more paired loci in homologous chromosomes.
Polygenic
A characteristic that is controlled by genes at more than one locus.
 

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