What is a crop-out Black and Tan
Black and Tan is a color pattern that can be found in dog breeds around the world. A Black and Tan dog is a dog that is mostly black but that has tan areas at the muzzle, eye brows, chest, and legs. It can vary greatly in expression with some very minimal black and tan dogs only having a small brown spot under the tail, while some dogs will be mostly tan with only a "saddle" of black on the back. These dogs are often called saddle tan, high tan or creeping tan but genetically it tests as black and tan, a modifier is thought to be responsible for the difference in expression1. A crop out black and tan is a dog that is born with the black and tan coloring in a breed that does not normally have black and tan coloring. This can come as a great shock to a breeder. Some may question whether a fence jumper may have been involved, while others may question the purity of their breeding dogs. However, just because a black and tan pup was born does not automatically bring into question the pedigree of the sire or dam nor the pups. There is another explanation: the genetics of the color itself.
The history of the black and Tan Coloration
Although, we will probably never known the exact origins of the Black and Tan color, we know that it is an ancient color that is present in some of the oldest breeds in existence including, the Afghan hound and the Saluki Hound. In fact, Abdul Farouk I, one of the first Saluki Hounds to be exported from Saudi Arabia was Black and Tan. Not only this, but the black and tan coloring has been clearly pictured in mosaic art dating from 200-100 BC and possible even older art from ancient Egypt2. Given it’s ancient origins it should be no surprise that it is widespread and found in dog breeds around the world.
The Genetics of Black and Tan
The black and tan color is controlled by a gene known as Agouti or ASIP1. All dogs have two alleles at Agouti one inherited from their sire and one from their dam. They will also pass one (and only one) of these alleles to each offspring with it being randomly determined which allele is passed. While, each dog can only have two alleles at Agouti (they can have two copies of the same allele this is called being homozgyous), there are four possible alleles: ay which causes the Fawn or Sable coloration, aw which is the color of the wolf and also thought to be wild-type (the “original” color), Black and Tan at which also causes saddle tan or high tan, and recessive black (a). These alleles are listed in order of dominance. This means that in order for a dog to be black and tan (or high tan) they must be either atat or ata at Agouti. They must have inherited one black and tan allele from each parent or a black and tan allele from one parent and a recessive black allele from the other parent. Since recessive black is relatively rare, in most breeds, this will mean BOTH parents must carry (and pass) a black and tan allele. Dogs that also carry ay or aw will NOT be black and tan even if they carry a black and tan allele. This does not mean however, that just because two dogs that carry black and tan are bred together that black and tan pups will be born. It only means that they have the possibility of having black and tan pups. Just to confuse things even more, the alleles at Agouti will be completely hidden if a dog also carries dominant black (which is different genetically from recessive black) or is recessive red (often cream or yellow in color without any black hairs). Therefore, a black, blue, chocolate or yellow dog can also carry a black and tan allele. An example of this would be Labrador retrievers. All Labrador retrievers are genetically atat at Agouti. However, because they also carry dominant black (or are recessive red), the black and tan coloration is “hidden” and not allowed to express. Even today the occasional black and tan Labrador puppy is born. This is an example of how the black and tan coloration can be carried for generations within a gene pool and never express. This also means that even though the foundation dogs of a breed were not black and tan (but especially if any were), the possibility exists, given the ancient origins of the black and tan coloration and it’s recessive nature, that it could still be within the gene pool even if black and tan puppies have not been produced.
Avoiding Black and Tan Puppies
So what can breeders today to do avoid black and tan puppies? Well, thankfully, there are now available DNA tests that can inform you if your breeding dogs carry a black and tan allele. If you do have a dog that carries a black and tan allele it is still possible to breed this animal without producing black and tan puppies. You just have to know the Agouti and dominant black status of your dog and any possible partners. A dog that is homozygous (has two copies) for dominant black (KB) or is negative for at (does not carry the black and tan allele), will never produce a black and tan puppy. It is genetically impossible for them to do so. So, if you have a valuable animal that carries black and tan you can avoid black and tan puppies by breeding them only to dogs that carry two copies of dominant black or who are negative for the black and tan allele. However, if you choose to do so please be aware that all puppies from this animal will have the possibility (50% chance) of also carrying a black and tan allele and if they are breeding quality should either be tested for black and tan prior to being sold or potential owners made aware of the possibility before sale.
If you would like to know more about Dog Color Genetics please see Canine Coat Color Basics.
Example Breeding Scenarios and the Chance of Black and Tan puppies
To create your own breedings and see the possible outcomes see the Puppy Coat Color Calculator
Parents are both Fawn with Black Mask who carry a black and tan allele (EMEM ayat)
|EMEM||ayay||25||Black Mask Fawn|
|EMEM||ayat||50||Black Mask Fawn Carries Black and Tan|
|EMEM||atat||25||Black and Tan with Black Mask|
|EMEM||atat||kyky||6.25||Black and Tan|
2A image of dogs in ancient EgyptNote the dog on the middle right. I was not able to verify this image or it's obtain a date