If you have a purebred dog, it is likely that he or she is quite similar to other dogs of the same breed, especially when it comes to the color of their coat. But what happens if a purebred puppy doesn't look exactly like its siblings when it's born? Chances are it's not a bug, but rather a hidden gene variant that decided to show itself. New research shows that some dog breeds have hidden coat colors — and in some cases, other traits — that have been lurking all along.
The researchers looked at a dozen different genes in 212 dog breeds. They analyzed these along with data collected for the development of DNA testing in dogs. In addition, they used standard breed descriptions from major U.S. and international dog breed registries to determine coat colors and tail lengths that were accepted within each breed.
"There was a lot of information that we didn't expect," the researcher said. “When it comes to different dog breeds, their standards are usually based on preference and aesthetics. We make assumptions for certain breeds based on what we expect their coat colors to be.”
Coat color genes have a significant amount of epistasis, meaning that what happens in one gene can mask what happens in another gene. Because of epistasis, it's rare to actually see those masked genes in a dog's coat color.
An example of a "false" allele — a gene variant that would cause a trait not allowed in a breed standard — is an allele that causes the brown color, which affects both hair pigment and skin pigment. The color is allowed in breeds such as the Labrador Retriever where it causes the chocolate color. However, researchers noted that in breeds where brown is not allowed, such as the Rottweiler and the German Shepherd Dog, brown alleles exist at low frequencies.
Another example of a foul allele is in the Weimaraner, which comes in both long-haired and short-haired varieties. At least one dog breed organization does not allow long-haired Weimaraners, while several others do. Of the Weimaraners sampled in this data, the long-haired allele is present at a frequency of 4%.
The same goes for other properties. For example, there are about 18 recognized dog breeds that have the genetic potential to be born without a tail – such as the popular Australian Shepherd. But the data shows that up to 48 of the breeds analyzed possess the tailless gene variant, usually at a very low frequency; one of those breeds is the Dachshund.
A breeder would certainly be surprised to see a Dachshund without a tail. The chances are slim, but our research shows the potential is there.
