If a purebred dog is born with a coat color that it is not supposed to have, it may be due to hidden genes. Kari Ekenstedt, DVM, Ph.D. who is the assistant professor of anatomy and genetics, along with Dayna Dreger, Ph.D., lead researchers in Ekenstedt’s canine genetics research laboratory studied 212 different dog breeds and found that gene variants caused breeds to have traits that the breed standard did not allow. These included coat color, and other traits. For example, they found that 48 different breeds had the tailless gene variant, such as the Dachshund. Although the variant was low, it is possible that a Dachshund could be born tailless.  

One of the “fault” alleles allows the brown color. This allele produces the chocolate Labrador Retriever, yet the researchers found the same allele in breeds that do not allow the brown color, such as the German Shepherd and Rottweiler.

The lesson learned from this study is that if a puppy is born that is not what the breed standard calls for, it is not necessarily due to “bad” breeding, but the expression of a trait that was hidden and has surfaced.