Research Identifies Twelve Dog Breeds at Risk for Brachycephalic Obstructive Airway Syndrome

Published in PLOS One, the research highlights significant variation in the prevalence and severity of BOAS within flat-faced breeds. BOAS is a chronic ailment resulting from lesions in the upper respiratory tract, which narrows the airway, leading to noisy breathing and potentially impairing a dog's exercise ability, sleep quality, and tolerance to heat or stress.

Dr. Fran Tomlinson, who co-led the study, explained that while some dogs are only mildly affected, more severe cases can drastically reduce a dog’s quality of life, raising serious welfare concerns. Though interventions such as surgery and weight management can provide some assistance, BOAS is hereditary, indicating a need for further research to mitigate risks in future generations.

While previous studies primarily focused on the most popular flat-faced breeds in the UK—namely French Bulldogs, Pugs, and Bulldogs—this research examined an expanded list of 14 breeds, including the Affenpinscher, Boston Terrier, Boxer, Cavalier King Charles Spaniel, Chihuahua, Dogue de Bordeaux, Griffon Bruxellois, Japanese Chin, King Charles Spaniel, Maltese, Pekingese, Pomeranian, Shih Tzu, and Staffordshire Bull Terrier.

Out of nearly 900 dogs assessed, 12 breeds displayed some level of breathing abnormality. The study identified Pekingese and Japanese Chin as being at particularly high risk for BOAS, with 89% and 82% affected, respectively. Other breeds such as the King Charles Spaniel, Shih Tzu, Griffon Bruxellois, Boston Terrier, and Dogue de Bordeaux were classified at moderate risk, with half to three-quarters of the dogs showing symptoms.

Staffordshire Bull Terriers, Cavalier King Charles Spaniels, Chihuahuas, Boxers, and Affenpinschers were found to be at mild risk, with about half showing signs of noisy breathing but few experiencing significant disease. No clinical issues were detected in the Pomeranian or Maltese breeds studied.

The research involved assessments at the Queen's Veterinary School Hospital and various breed-specific events. An adapted version of the UK Kennel Club's Respiratory Function Grading Scheme was used to evaluate the additional breeds.

The findings emphasized that the risk of BOAS is also influenced by anatomical features, with narrower nostrils linked to increased risks. High rates of nostril narrowing were observed in Pekingese and Japanese Chin, with only 6% and 18% maintaining open nostrils, respectively.

Particularly notable was the correlation between tail length and BOAS in Staffordshire Bull Terriers, where dogs with longer tails were 30% less likely to have the condition.

Researchers also noted that weight plays a significant role in the Cavalier King Charles Spaniel, Shih Tzu, and Affenpinscher breeds; reducing weight can potentially lower the risk of BOAS.

Dr. Jane Ladlow, who co-led the study, suggested that understanding these risk factors could aid breeders and prospective owners in making informed decisions about selecting less at-risk dogs. It may also guide judges in dog shows to avoid rewarding traits that could compromise health.

The study underscores the need for a breed-specific approach to address BOAS across different populations, and highlights that weight, nostril narrowing, and craniofacial ratio only account for a portion of the variations in BOAS status. Hence, conducting breathing assessments remains the most effective method for evaluating BOAS risk.

The research was supported by funding from The Royal Kennel Club Charitable Trust.