Pekingese (left) and Japanese Chin (right) dogs are at high risk of breathing problems
Michael Schultze, KATAMOUNT/Alamy
Dog owners are being warned to be wary of a much wider range of breeds when buying puppies, after research shows serious breathing disorders are more common than previously thought.
Dogs with shorter snouts and flatter faces are known as brachycephalic breeds and have become “very popular” in recent years, says Francesca Tomlinson of the University of Cambridge.
But as the popularity of these breeds has increased, so have the health problems associated with them – particularly brachycephalic obstructive airway syndrome (BOAS), easily recognized by noisy breathing. This condition can lead to an inability to exercise, sleep and cope with heat or stress.
Concerns over BOAS have primarily focused on English bulldogs, French bulldogs and pugs. To find out which other breeds are at risk, Tomlinson and her colleagues studied 898 dogs from 14 breeds: affenpinscher, Boston terrier, boxer, cavalier King Charles spaniel, Chihuahua, Dogue de Bordeaux, Griffon Bruxellois, Japanese chinchilla, Maltese, Pekingese, King Charles spaniel and Staffordshire terrier, Pomeranian shi terrier.
All dogs underwent respiratory testing and were subjected to a series of detailed body and facial measurements.
The Pekingese and Japanese Chin had the highest risk of BOAS, with over 80 percent of dogs affected. Five breeds had a moderate risk, with BOAS seen in half to three-quarters of dogs: Cavalier King Charles spaniel, shih tzu, Griffon Bruxellois, Boston terrier and Dogue de Bordeaux. Only among the Maltese and Pomeranian breeds did they find no dogs with clinically significant disease.
The researchers found that three main factors led to breathing disorders: obesity, narrowing of the nostrils and extreme flatness of the face. The analysis suggests that other characteristics, such as very short or screw tails, may also be associated with anatomical changes linked to BOAS. “This suggests that it is not just flatness alone that determines risk, but there are many other factors at play,” says Tomlinson.
She says prospective owners should look for puppies from parents who have undergone appropriate health testing and should educate themselves about the potential health consequences of extreme bodily, especially facial, changes.
“It’s not necessarily about eliminating the defining characteristics of a breed, but about avoiding extremes and supporting breeding decisions that prioritize function as well as appearance,” she says.
Breeders should know that it is not only the breed that determines negative outcomes, she says, but the degree of exaggeration of certain physical characteristics. “It gives us something practical to work with – it suggests that opting out of extremes can help reduce disease risk.”
Anna Quain of the University of Sydney, Australia, says people don’t appreciate that a “cute” flat appearance predisposes these dogs to chronic oxygen deprivation and heat stress.
Breeding dogs for flat faces is like “designing a car without a radiator”, she says. “If we are deliberately bringing dogs into the world, we should base those decisions on welfare first rather than the preservation of a human idea of what a dog should be.”
Paul McGreevy, also at the University of Sydney, says the study confirms what most vets already know. “Airway compromise is prevalent among flat-faced dogs and varies significantly between and among breeds,” he says.
“For dogs struggling to excrete carbon dioxide through compromised airways, breed labels are irrelevant. Whether they are identified as a bulldog cross or registered as a Pekingese or Boston terrier is a human construct.”
However, he is concerned about certain aspects of the methodology. “The assessment relies on subjective listening to breath sounds classified by ear as mild, moderate or severe, but provides no evidence that this is used consistently across 14 different breeds,” says McGreevy. “Even more problematic, the authors acknowledge that their fitness test depends on individual speed ability and temperament.”
Tomlinson says the assessment includes objective criteria, including whether abnormal airway noise is audible with or without a stethoscope, and the grading follows a standardized protocol. “The goal (of the exercise test) is not to assess athletic performance, but to see how the airways respond during mild exertion,” she says.
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