The color of a dog's coat could be linked to its health — at least for one globally popular pet.
Chocolate Labrador retrievers tend to live shorter lives and have a higher rate of skin and ear diseases than their black or yellow-coated peers, according to a new study published yesterday (Oct. 21) in the journal Canine Genetics and Epidemiology. [10 Things You Didn't Know About Dogs]
An international group of researchers examined data from more than 2,000 Labradors living in the U.K. in 2013. The data was collected as a part of research project called VetCompass, a collaboration between the University of Sydney and the Royal Veterinary College at the University of London. The group of around 2,000 Labs was randomly selected from a larger dataset containing more than 33,000 Labrador retrievers.
The researchers found that, within the sample set of the dogs they studied, the incidence of ear and skin disease was much more prevalent in chocolate Labs than in other Labs.
For example, rates of a common skin infection in dogs called pyotraumatic dermatitis — more commonly known as "hot spots" — were more than twofold higher in chocolate Labs than black and yellow Labs. Similarly, "swimmer's ear," or otitis externa, an infection of the ear canal, also turned up more often in chocolate Labs than in other colored Labs.
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.
Originally published on Live Science.
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Yasemin is a staff writer at Live Science, covering health, neuroscience and biology. Her work has appeared in Scientific American, Science and the San Jose Mercury News. She has a bachelor's degree in biomedical engineering from the University of Connecticut and a graduate certificate in science communication from the University of California, Santa Cruz.