Veterinary nurses are often asked their opinion about the health of flat-faced (brachycephalic) dogs. Until now, their opinion was the best that veterinary nurses could offer. However, with the advent of Big Data research programmes such as VetCompass at the RVC, veterinary nurses are now being empowered to answer these common questions using evidence rather than just opinion. This article helps veterinary nurses to answer questions related to brachycephalic dogs but other VetCompass papers provide answers to many other important everyday questions in general practice.
Brachycephalic dog breeds, such as French Bulldogs, Pugs and (British) Bulldogs, are highly cherished in the UK. However, steeply rising popularity and evidence of health issues associated with their exaggerated body shape means that there are growing welfare concerns about these breeds. There is evidence of brachycephalic predisposition to respiratory disease, eye disease, dystocia, spinal disease, heat stroke and pneumonia, as well as shorter lifespans. But is this the full story? Perhaps science favours reporting the bad stuff about breeds but is less in-terested in reporting bland news where breeds were not predisposed or even had reduced risk of developing (i.e. disorder protection).
With this background of offering a level playing field in evaluating the health of brachycephalic dogs, VetCompass recently reported on the risks of common disorders between brachycephalic dogs compared with mesocephalic (medium length skull, e.g. Bichon Frise) and dolichocephalic (long skull, e.g. greyhound) types.
Demography
The study included a random sample of 22 248 dogs attending 784 veterinary clinics from 955 554 dogs under veterinary care in 2016. These dogs included 4169 (18.74%) brachycephalic, 10 341 (46.48%) mesocephalic, 1744 (7.84%) dolichocephalic and 5994 (26.94%) crossbred types. Even this breakdown by skull-shape is useful information for veterinary nurses. The most common brachycephalic breeds were Chihuahua (22.91%), Shih-tzu (19.07%), Cavalier King Charles Spaniel (10.43%), Pug (9.91%), French Bulldog (9.55%), Lhasa Apso (7.46%), Boxer (5.88%) and British Bulldog (5.01%). Who knew that Chihuahuas were so popular!
Brachycephalic dogs differed to other dogs in many ways. Brachycephalic dogs were younger: median 3.31 years compared with 5.33 years for mesocephalic types and 5.07 years for dolichocephalic types. Brachycephalic dog were lighter: median 8.75 kg compared with 16.98 kg for mesocephalic types and 25.80 kg for dolichocephalic types. Brachycephalic types were less likely to be neutered; 36.70% compared with 46.13% for mesocephalic types and 46.43% for dolichocephalic types. We need to consider these differences when comparing health between these groups of dogs.
Health
Across all types of dogs, 65.84% had at least one disorder recorded during 2016. After adjusting for other variables such as absolute and relative bodyweight, age, sex, neuter and insurance status, brachycephalic types had 1.27 (95% CI 1.13–1.43, p<0.001) times the odds of having at least one disorder compared with crossbred types. Brachycephalic dogs also had increased odds of having at least one disorder compared with mesocephalic and dolichocephalic dogs. This was early evidence suggestive of overall poorer health in brachycephalic dogs as a group.
A list was generated of the 30 most common disorders across both the brachycephalic and non-brachycephalic disorders to ensure no bias towards either group of dogs.
The most common disorders in brachycephalic types were periodontal disease (prevalence = 11.63%), otitis externa (7.27%), obesity (6.38%) and anal sac impaction (5.97%). There were 8/30 disorders with significantly higher odds (i.e. disorder predisposition) for brachycephalic types compared with non-brachycephalic types. These included corneal ulceration (OR 8.40), heart murmur (OR 3.52), umbilical hernia (OR 3.16), pododermatitis (OR 1.66), skin cyst (OR 1.52), patellar luxation (OR 1.40), otitis externa (OR 1.29) and anal sac impaction (OR 1.24). Two disorders had reduced odds for brachycephalic types (i.e. disorder protection): undesirable behaviour (OR 0.52) and claw injury (OR 0.45). Brachycephalic dogs were much more likely to be predisposed to common disorders than to be protected.
Conclusions
This study provides strong evidence that brachycephalic breeds are generally less healthy than their non-brachycephalic counterparts. Potential solutions to these welfare issues include selection towards less extreme conformation or reducing the popularity of some of these breeds. Please share widely this message from the UK Brachycephalic Working Group to everyone involved with dogs: ‘Stop and think before buying a flat-faced dog’.