The color of a dog may dictate how long it lives, a new study suggests.

In the study, a team of researchers led by the University of Sydney found that chocolate Labradors live significantly less than their black and yellow counterparts.

Published in the open access journal Canine Genetics and Epidemiology, the study reveals how overusing dogs with popular traits may cause health problems.

The study

The study first started in the UK with colleagues from the Royal Veterinary College through a VetCompass™ Programme, which collects and analyzes electronic patient data on dogs.

“I helped to set-up VetCompass in the UK some years ago and was keen to see what its data revealed about Labradors in general,” said lead researcher Paul McGreevy, a professor of animal behavior and animal welfare science at the University of Sydney.

According to the paper’s companion piece on The Conversation, written by McGreevy and  co-author Bethany Wilson, an honorary affiliate at the University of Sydney, the researchers looked at the UK veterinary records of more than 33,320 Labrador retrievers through the VetCompass program.

Then, they extracted data on death and disease from a random sample of 2,074 (6.2 percent) of these dogs.

The result

They found that chocolate Labradors not only live less but also are more likely to have ear infections and skin disease than their black and yellow counterparts.

In the UK, the median life expectancy of non-chocolate Labradors is 12.1 years, more than 10 percent longer than those with chocolate coats.

The prevalence of ear inflammation (otitis externa) was twice as high in chocolate Labradors, who were four times more likely to have suffered from pyotraumatic dermatitis (also known as hot-spot).

Across the entire Labrador population, the most common health conditions found were obesity, ear infections and joint conditions.

The prevalence was higher among male dogs who had been neutered.

“We found that 8.8 percent of UK Labradors are overweight or obese, one of the highest percentages among dog breeds in the VetCompass™ database,” McGreevy said in a statement.

The researchers were surprised because they found nothing similar in their previous studies with pugs or Cavalier King Charles Spaniel.

As part of VetCompass Australia, which operates as a consortium comprising all of Australia’s veterinary schools and is supported by the Australian Research Council, the team is currently researching if the UK findings also holds true for Labradors in Australia, where Labradors are the most popular breed of dogs.

“We are currently undertaking a parallel study of Labrador retrievers in Australia to establish whether or not these colour-related differences persist in the relatively isolated Australian population,” McGreevy said.

“If we fail to find the same differences (in Australian Labradors), this may point to the overuse of certain breeding lines in the UK.”

Currently, seven different veterinary schools in Australia are looking into local breed-specific data to look for other health problems related to coat colors.

Following popular demand

The researchers suggest that the health problems in chocolate Labradors may be pertinent to overuse of their genes.

Because chocolate is a recessive gene, meaning both parents must carry it, gene pool for chocolate Labradors becomes shallower and breeders often end up overusing dogs that they know for sure have the recessive gene.

“It may be that the resulting reduced gene pool includes a higher proportion of genes conducive to ear and skin conditions,” McGreevy said in a statement.

So, what should breeders do?

“Breeders could focus more on selecting for good temperament and health, but only if less attention were paid to superficial traits,” McGreevy and Wilson advised in their article for The Conversation.

“After all, a dog can never be the ‘wrong’ colour.”