BOAS review highlights grading, earlier assessment, and treatment
Bottom line
Version 1
A 2022 review in Veterinary Clinics of North America: Small Animal Practice pulls together a practical framework for grading, assessing, and treating brachycephalic obstructive airway syndrome, or BOAS, in dogs. The authors, Kelley M. Thieman, Kathleen M. Ham, and Bryden J. Stanley, describe BOAS as a progressive disorder driven by primary airway abnormalities that increase resistance and turbulent airflow, then trigger secondary changes that further narrow the airway. Their clinical approach emphasizes careful respiratory auscultation, assessment of inspiratory effort, and exercise tolerance testing to sort dogs by disease severity and guide treatment decisions. That approach aligns with the University of Cambridge respiratory function grading system, now also offered in North America through OFA, which uses a brief exam plus a three-minute exercise test to classify dogs from grade 0 to grade III. (cir.nii.ac.jp)
Why it matters: For veterinary professionals, the review reinforces that noisy breathing in brachycephalic dogs shouldn't be dismissed as breed-normal. Current reference sources from Cornell and ACVS note that BOAS can worsen over time, impair exercise, sleep, eating, and thermoregulation, and is associated with secondary problems including laryngeal collapse, aspiration risk, and gastrointestinal disease. Conservative management still matters, especially weight control, heat and stress avoidance, and harness use, but earlier surgical intervention is generally linked to better outcomes in appropriately selected patients. (vet.cornell.edu)
What to watch: Expect continued uptake of standardized BOAS grading in general practice, breeding programs, and referral workflows, especially as North American screening expands to more brachycephalic breeds. (ofa.org)
Version 2
A widely cited 2022 review on brachycephalic obstructive airway syndrome is helping define how clinicians think about grading, assessing, and treating BOAS in practice. In Veterinary Clinics of North America: Small Animal Practice, Kelley M. Thieman, Kathleen M. Ham, and Bryden J. Stanley outline a structured approach built around what clinicians can observe and hear: respiratory noise, inspiratory effort, and performance before and after exercise. The central message is straightforward: BOAS is not a cosmetic issue or a benign breed trait, but a progressive airway disease that deserves systematic assessment and earlier intervention when indicated. (cir.nii.ac.jp)
That framing reflects a broader shift in small animal medicine over the past decade. Brachycephalic breeds have remained highly popular, but veterinary and welfare groups have pushed back on the normalization of chronic respiratory compromise. The University of Cambridge functional grading model, later adapted into the Respiratory Function Grading Scheme, helped move the field toward a more objective, reproducible way to identify clinically affected dogs. OFA says that program is now available in North America, and in an April 2026 update it expanded eligibility to 14 additional breeds, signaling broader use beyond the classic bulldog, French bulldog, and pug focus. (ofa.org)
The grading approach itself is intentionally practical. Cambridge's published instructions describe a pre- and post-exercise assessment based on respiratory noise, inspiratory effort, and dyspnea or cyanosis, with a three-minute trot or brisk walk used to unmask disease that may be less obvious at rest. Dogs in grade 0 have no audible signs before or after exercise, while grade I dogs may have only mild signs detectable on auscultation. Grades II and III indicate clinically affected dogs, with moderate-to-severe noise and effort, and in the most severe cases, dyspnea, cyanosis, syncope, or inability to exercise. (vet.cam.ac.uk)
Background references from Cornell and ACVS underscore why that matters clinically. BOAS is tied to primary abnormalities such as stenotic nares, elongated soft palate, everted laryngeal saccules, and, in some dogs, hypoplastic trachea. Over time, the increased effort required to breathe can produce secondary inflammation and collapse, worsening airway compromise. Cornell notes that severity often increases with age, and that associated conditions can include laryngeal collapse, bronchial collapse, aspiration pneumonia, hiatal hernia, and gastroesophageal reflux. (vet.cornell.edu)
Treatment remains a mix of medical management, environmental control, and surgery, depending on severity. Conservative care includes keeping dogs lean, minimizing heat and humidity exposure, reducing stress, controlling activity, and using a harness instead of a neck collar. For more affected dogs, surgical correction of stenotic nares, elongated soft palate, and everted saccules remains the mainstay, although referral teams continue to stress the anesthetic and postoperative risks in these patients. Cornell's guidance adds that earlier surgery, particularly before advanced secondary changes develop, is associated with better outcomes, while dogs with laryngeal collapse tend to fare less well. (vet.cornell.edu)
Industry and expert commentary increasingly positions BOAS as more than a surgical problem. A 2022 Veterinary Quarterly review described it as a chronic, lifelong, debilitating condition and argued that management has to extend beyond airway surgery alone. That broader lens includes client education, perioperative planning, long-term weight management, and breeding decisions aimed at reducing disease prevalence rather than simply treating its consequences. Cornell likewise states that dogs with breathing difficulty, hypoplastic trachea, or a need for surgical correction should not be considered for breeding. (tandfonline.com)
Why it matters: For veterinary professionals, the biggest takeaway is that standardized grading can improve decision-making at multiple points: wellness visits, pre-anesthetic screening, referral timing, emergency triage, and conversations with pet parents about expectations. It also gives general practitioners a more defensible way to distinguish clinically unaffected dogs from those whose respiratory compromise is affecting quality of life, even when pet parents perceive the signs as normal for the breed. In a practice environment where French bulldogs, English bulldogs, pugs, Boston terriers, and other brachycephalic breeds remain common, BOAS assessment is increasingly becoming part of routine preventive and surgical medicine, not just specialty care. (ofa.org)
What to watch: The next phase is likely to center on wider use of formal respiratory grading in North America, more breed-specific screening efforts, and continued pressure to link clinical BOAS assessment with breeding guidance, earlier referral, and measurable outcome tracking after surgery. (ofa.org)