A Lab’s fur color even seemed to be associated with how long the dog lived. The researchers found that non-chocolate Labs lived, on average, 12 years in the U.K., whereas chocolate Labs lived, on average, 10.7 years, a drop of more than 10 percent.
The researchers noted that the reason for these links — between fur color and dog health — are still unknown. Indeed, the finding “merits further investigation,” the authors wrote in the study.
However, genetics plays a role, the researchers said.
“The relationships between coat color and disease may reflect an inadvertent consequence of breeding” dogs to be certain colors, lead author Paul McGreevy, a professor of veterinary science at the University of Sydney and chair of board of VetCompass, said in a statement.
A trait like a dog’s fur color is dictated by the combination of two genes: one from the mother and one from the father. A gene can either be “recessive” or “dominant.” The chocolate color in Labs is coded by recessive genes; this means that the puppies must receive one gene from each parent that codes for the chocolate color in order for the puppy to have chocolate-colored fur. (If the gene was dominant, the puppy would need only one gene to have the trait).
“Breeders targeting this color may therefore be more likely to breed only Labradors carrying the chocolate coat gene,” McGreevy said. This restricts the gene pool, and the dogs in this smaller pool might be more predisposed to skin and ear conditions, which means their puppies are more likely to inherit them, according to the study.
It’s unclear whether this holds true in other breeds, as well as in Labs around the world. Now, the researchers are conducting a similar study of Labs in Australia.