COAT COLOR INHERITANCE IN THE AMERICAN PIT BULL TERRIER A Locus Ay Dominant Red Ay produces dogs that are red or yellow. This is responsible for fawn, red and buckskin dogs. While it is dominant sometimes there is Incomplete dominance of tan point. A dog who is Ay/at could be of the same phenotype as a Ay/Ay dog however some appear shaded Sable or Smut. These dogs have an overlay of dark hairs and even light tan points. The lighter hairs underneath the darker hairs will be visible unlike a true tan point who will be solid color with distinct points. There are also dogs with some saddling or widows peaks who do not posses a tan point gene allele. There is currently another unknown modifier for this. at Recessive Tan Point at/at would produce a tan point dog. The coat color would be dependent on what other genes the dog inherits at other Locus. Black & Tan, Chocolate & Tan, Blue & Tan or Lilac & Tan. B Locus B Dominant Black Pigment Pigment of the nose, eye rims, lips and other areas of skin will be black. The hairs within a red dogs coat will be black, tan point will be black & tan, brindle will have black stripes so on & so forth. b Recessive Liver pigment Pigment of the nose, eye rims, lips and other areas of skin will be red. The black hairs within the coat of a red dog will instead appear as be red. A tan point dog would be chocolate and tan, a black dog will be chocolate, a brindle will have red or chocolate stripes. This mutation modifies both black skin pigment and black coat pigment. Masked dogs will have a chocolate mask. D Locus D Dominant Black Pigment This is like the dominant B. Black pigment. d Recessive Dilute Pigment Pigment of the nose, eye rims, lips and other areas of the skin will be blue/gray. The black hairs within the coat of a red or fawn will also be blue. Tan points will be blue and tan, black dogs will be of blue coat, brindle dogs will have blue stripes. Like the liver gene this modifies both black skin and black coat pigment. When a dog inherits both liver and dilute they are a color known as Isabella (chocolate dilute). Also termed lilac in the APBT. Red dogs inheritin6 both are known as champagne. E Locus E Dominant black hairs This is what allows for the production of black pigment in a dogs coat. This would include all black hairs from a solid black coat to a red dog with only a few black hairs. Em Dominant Black hairs with mask This modifier does the same as above but this variant causes a mask. If the dog is a liver the mask will be chocolate and if a dilute the mask will be blue. The mask can vary on how much of the face is covered. Sometimes it does not extend past the muzzle. It only requires one Em allele to produce a mask but being homozygous may play into how deep and dark the mask is. Some times a mask will reduce intensity with age, as seen with this dog. The white causes the deletion of both brindle & mask. e Recessive Red/Yellow Essentially this gene inhibits the production of black pigment. This only applies to the coat. Recessive red dogs can still have black noses (or red or blue). Though it is thought to be a cause of dudley nose (flesh colored, lacking pigment). This gene causes fawn or red dogs who show no amount of black hairs in the coat. Almost all red dogs have some black hairs whether that be few or many. But a recessive red/yellow will have none. Since the dog can't produce black coat pigment a black, black & tan point or brindle dog will appear to be a red dog. K Locus Kb Dominant Black This is self explanatory producing a dog of solid black coat. Those who are red nose (liver) will be chocolate and those who are blue nose (dilute) will be blue. Kbr Dominant Brindle Brindle is dominant but works with the A Locus in that it produces a striped pattern over a red or fawn base coat. In tan point dogs the brindle can be seen in the tan points. However black will mask the presence of brindle if a dog inherits one of each allele. Red nose dogs will be chocolate, red, buckskin or fawn brindle. Blue nose dogs will be blue brindle. ky Recessive A Locus expression / non black This recessive gene allows the expression of the A Locus. Whether that is fawn, smut or tan point. S Locus White Spotting White can mask any color as it causes the hair to be unable to produce pigment. As an example a dog with a Kb allele is still genetically black and capable of producing black puppies even if they themselves are solid white. Since white causes a lack of pigment it can also be responsible for blue eyes, bi eyes or parti eyes. It causes butterfly nose as well. Solid white homozygous for piebald Sp Piebald gene appears to be a co dominant. A dog who is homozygous for piebald will have high amount of color deletion and may even be solid white. Like the dog above. The next dog pictured is also homozygous for piebald but has brindle markings. S Solid or non piebald Homozygous for solid color (doesn't carry piebald). These dogs will only produce solid colored dogs when bred together but if they are bred to a dog carrying piebald it is possible for their pups to have white markings. When bred to a homozygous piebald all pups will have white markings to various degrees. As mentioned above piebald shows a co dominance with solid/non piebald. Therefore a heterozygous dog will have some white markings like the dog pictured below. Bi eyes due to piebald. One amber, one blue. Parti eye due to piebald. One eye is both brown & blue. Butterfly nose. Reduced nose pigment due to piebald. I will post a part 2 but it is for unknown genetics. Only 20 pics are allowed so I had to split it.