Сoat color genetics of Italian Greyhounds
There are quite a lot of articles and books about the dog coat colors genetics and this article does not pretend to reveal unique discoveries.
The purpose of this article is to explain as simply as possible the basics of inheritance of coat colors in the Italian Greyhound breed, and also to share our personal observations of the color inheritance in our breed.
During multiple conversations we realized that, despite the availability of many open Internet resources and books about the dog coat colors genetics, the principles of the inheritance in Italian Greyhounds are still not clear for many people involved in breeding.Additional confusion arises because many people are guided by information that has already become obsolete.
The point is that relatively recently genetics have discovered a separate locus K, which is responsible for the dominant black color and it radically changed all the formulas of the colors of the Italian Greyhounds, which were previously considered as correct and still exist in many articles on the Internet.
About genetics you can write a lot and in difficult way, but I thought for a long time how to put the material in the simplest form and as a result this table was created.
Inheritance of coat color in the Italian Greyhounds
(Right-click the table to open it in the new tab)
In the table I tried to present all possible combinations of genes of the main loci and the result of their interaction. Since the breeders pay a lot of attention to the purity of color and the intensity of the pigment - I selected in separate groups the combinations of genes that give these qualities.
Thus, you do not need to have deep knowledge in genetics to understand how this or that color in our breed turns out.The table shows the main loci, which affect the color of Italian Greyhounds.
I want to pay reader’s attention to the fact that there are already available genetic tests for all these loci, and everyone can find out exactly what color his dog has genetically and, accordingly, what it can give in breeding. From our experience, the best variety of tests for dog coat color genetics provides laboratory Genomia (Czech Republic).
BRIEFLY ABOUT EACH LOCUS:
Locus A - responsible for the red color, which in our breed is commonly called - isabella or fawn. This locus contains genes Ay->aw->at->a (arrows show the level of dominance of the locus genes, i.e. Ay dominates above aw, etc.).
There is a theory that emerged as a result of the American study of 23 Italian Greyhounds, which states that the Italian Greyhounds have only the Ay gene in this locus. Therefore, only the colors with Ay Ay genotype are considered in the table.Although the colors of some Italian Greyhounds make me think about the presence of aw or at in their genotype (the "seal" color, for example). Soon we are going to present the result of our own genetic research in this area.
Locus B - responsible for the type of pigment. This locus contains genes B->b, where B is the black pigment, and b is the brown pigment. There are representatives of the Italian Greyhounds with the genotype bb (these are isabella with a purple or brown nose), but most have the genotype BB or Bb. Therefore, only colors with genotype BB are considered in the table.
Locus E - responsible for the expression of black pigment. In this locus genes Еm->Eg->E->Eh->e are contained.
There are three genes of this locus in our breed:
Em - responsible for the appearance of the mask. As can be seen from the table, all dogs that have the Em gene will have a (visible or invisible) mask on the muzzle, regardless of the second gene in this locus.
E is the normal distribution of the black pigment. If a dog with a gene E also has a K gene, then it will be black or gray/blue.
e - blockage of the distribution of black pigment. It completely removes black color from the coat, while it does not affect the pigment of the skin. The genotype ee is also known as "ee-red" or “recessive red”. As you can see from the table, when the black color is removed, there is nothing left for the dog as to be red, regardless of the presence of the K gene.
Locus K is the most recent discovery in color genetics that has reversed the knowledge of inheritance of black/gray color and has confused many respected breeders who have been engaged in the breed for a long time and got accustomed to believe that the dominant black corresponds to gene a in locus A.
In this locus, the genes K->kbr->k were found. The Italian Greyhounds have two of them - K and k.The genes of the locus K allow the appearance of black and gray/blue colors of the Italian Greyhounds. The table shows all possible interactions of the locus K genes with the genes of the locus D.
As can be seen from the table, the pure black and blue colors are mostly obtained when the dog is homozygous for the K locus with the KK genotype.
Although the gene K theoretically dominates over the k gene (i.e., it is enough to have a genotype Kk to get a black/gray color), but as practice shows, most dogs with the Kk genotype have at least a small admixture of red or not solid color. Apparently with this genotype, strong agouti genes, still piercing their way and at least a little but make their own adjustments to the dog’s color. In case if Kk dog doesn't have strong agouti genes - he will have quite a clean color.
Locus D - responsible for the intensity of the color, also the genes of this locus affect the pigment of the skin. This locus contains genes D->d.
D - gives an intense color and dominates above d. As can be seen from the table, if there is at least one D gene in combination with at least one K, the dog will be black. And if without K - then red, but with a good pigment.
d - gives dillution (weakening) of the pigment both in coat and on the skin. That is why dogs with the dd genotype will not only have a dilluted color (blue/gray), but also a dilluted pigment of the nose, eye rims, nails.
In addition to the loci, represented in the table, there are also locus I (intensity of red color) and S (white spots) in our breed. The genes of these loci impose an imprint on the main color, which is obtained by the interaction of genes presented in the table.
Locus I (formerly called C) - is responsible for the intensity of the red color. Contains genes I->i. I - intense color (darker isabella), i - not intense (lighter isabella).
It is the gene i, together with the e gene, that can lighten the isabella to a very light shade of the "cream" type.
The inheritance of the genes of this locus has a polygenic type, since the intensity of the red is not a qualitative but a quantitative characteristic. I.e if to take genotype II for 100% intensity (red color of Irish setter), then genotype Ii will have about 50% of intensity, and the intensity of the genotype ii will tend to zero (and we get “cream” color).
Locus S - responsible for the presence/absence of white spots. It contains the genes S->si->sp->sw. There are breeds in which the gene sw of this locus is responsible for the white color of the coat, but not in our breed.
There are two genes from this locus in the Italian Greyhounds: S - absence of white spots and si - presence of white spots on the chest, paws, muzzle, neck. The size of white spots is also a polygenic factor.
Finally, I would like to mention such a gene as G - a gene of progressive graying, which is located in the locus G.
It's not a secret that many Italian Greyhounds early begin to go gray, but it is not because of G gene.
Early graying of the Italian Greyhounds, of course, is also due to genetics, but it has a polygenic nature of inheritance.
Gene G is present in the breeds, where the colors are formed by it: yorkshire terrier, poodle, kerry-blue terrier ... The color of the puppies of such breeds differs radically from the color of adult dogs. For example, puppies are born black or brown and "blossom" in gray or isabel to a certain age.
Genetics is an amazing science, and is rapidly developing. Much that could be just guessed ten years ago - now is already has clear scientific justifications and is susceptible to precise calculations. In the following articles, we will try to reveal the veil of the mystery of the inheritance of the main genetically transmitted problems in the Italian Greyhound breed.
Kennel "Sunnymoon Place"
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