Why chocolate might be especially bad for Labs health
Ear, skin disease more common in chocolate Labrador retrievers than black or yellow, study finds.
Chocolate Labrador retrievers have a higher incidence of some diseases and a shorter life span than other Labs, according to a recent UK study. Erik Lam/stock.adobe.comBy all accounts, Labrador retrievers make fantastic pets, despite their quirky side (chewing is cute, right?). Smart, playful and devoted, Labs have reigned supreme as the most popular dog breed in the United States since 1991, according to registration statistics from the American Kennel Club.
Like many breeds, Labs are prone to certain health problems, including orthopedic, ophthalmic, endocrinologic and nervous system conditions. But which health problems are the most prevalent? A collaborative study conducted by investigators at the University of Sydney in Australia and the Royal Veterinary College in London addressed this question by examining and comparing the demography, mortality and commonly recorded diseases in Labrador retrievers under veterinary care in the United Kingdom in 2013, with an eye toward determining whether coat color is associated with disease development.
“This is the first study to include a large number of Labrador retrievers based on records gathered from hundreds of UK vet clinics,” said study coauthor Paul McGreevy, BVSc, PhD, MRCVS, MACVS (animal welfare), professor of animal behavior and animal welfare science at the University of Sydney School of Veterinary Science, in a press release about the study. “It provides owners with information on the issues that they should look out for in Labrador retrievers."
Demographics and mortality
Study data were extracted from the VetCompass database, which includes anonymized demographic and clinical data from pets throughout the United Kingdom. Of the 455,557 dogs that received veterinary care in 2013, a total of 33,320 (7.3%) were Labrador retrievers, including 15,427 females (46.4%) and 15,252 males (53.6%), with a collective mean body weight of 33 kg (72.8 lb).
Illness and mortality data elicited from a random sample of 2,074 (6.2%) of these Labradors revealed that 1,277 (61.6%) had at least one recorded disorder and 176 died during the study period. Mortality did not differ significantly between male and female Labs, but neutered dogs lived slightly longer than their intact counterparts (12.5 vs. 11.6 years).
Overall, the most commonly reported conditions in the sampled dogs, in order of prevalence, were ear infections (10.4%), overweight/obesity (8.8%), degenerative joint disease (5.5%), lameness (4.4%) and periodontal disease (4.2%).
The most commonly reported conditions in the sampled dogs, in order of prevalence, were ear infections (10.4%), overweight/obesity (8.8%), degenerative joint disease (5.5%), lameness (4.4%) and periodontal disease (4.2%).
The role of coat color
Of the three coat colors recorded for Labrador retrievers in VetCompass, black was the most common, at 44.6% of the Lab population; yellow Labs made up 27.8% and chocolate 23.8%. Data analysis revealed that chocolate Labs are more prone to certain health conditions than black or yellow Labs. The median overall lifespan for all Labrador retrievers in the database was 12 years, but chocolate Labs lived about two years less than non-chocolate Labs (10.7 vs. 12.1 years). The most common causes of death in the 2,074-dog sample were musculoskeletal disorders and cancer.
In particular, chocolate Labs seemed more prone to skin and ear disease. Otitis externa was identified in 23.4% of chocolate Labs, 17.0% of yellow Labs and 12.8% of black Labs. Likewise, the prevalence of pyotraumatic dermatitis in chocolate Labs (4.0%) was more than double that in black and yellow Labs (1.1% and 1.6%).
The authors speculated that the higher number of dermatologic and otic infections in chocolate Labradors may be the result of genetics. “The chocolate Labs were diagnosed with more otitis and much more skin disease,” Professor McGreevy said in an email to dvm360. “Whether this reflects compromised immune responses more generally merits further investigation.”
Chocolate color is recessive in dogs, meaning that both parents must carry the gene for chocolate color in order for puppies to be chocolate in color. Breeders targeting for the chocolate coat color may be more likely to use only those Labs that carry the chocolate coat gene, and the resultant reduced gene pool may include a higher proportion of genes involved in ear and skin conditions. Professor McGreevy's take? “Breeding for color is questionable.”
Study limitations and implications
Despite the large size of the study, it excluded dogs not in the VetCompass database (i.e., those that didn't receive veterinary care in 2013). In addition, Professor McGreevy noted, the results relied “entirely on the accuracy of practitioners' diagnoses and the details in the patients' electronic medical records.” Therefore, the findings may underestimate the true prevalence of disease in this breed. Nevertheless, the data provide a basis for identifying specific health concerns in Labrador retrievers and offer insight into devising campaigns that could improve the overall health and welfare of this beloved breed.