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Brachycephalic Obstructive Airway Syndrome (BOAS) in Dogs


Introduction

Brachycephalic Obstructive Airway Syndrome (BOAS) is a progressive upper airway condition affecting flat-faced (brachycephalic) breeds such as Bulldogs, Pugs, French Bulldogs, and Shih Tzus. Their shortened skull shape contributes to airway narrowing, making normal breathing difficult.

For dog owners, BOAS can cause noisy breathing, exercise intolerance, and even life-threatening airway collapse. For veterinarians, it is a multifactorial disease requiring careful diagnosis, peri-anaesthetic management, and often surgical intervention.

Pathophysiology

  • Stenotic nares – narrowed nostrils restrict airflow
  • Elongated soft palate – excessive tissue obstructs the airway
  • Everted laryngeal saccules – tissue pulled into the airway from chronic negative pressure
  • Hypoplastic trachea – congenitally narrowed trachea

Chronic obstruction can lead to laryngeal collapse, worsening respiratory compromise over time (Poncet et al., 2006).

Clinical Signs

For dog owners, watch for:

  • Loud snoring or noisy breathing
  • Exercise intolerance, especially in warm weather
  • Gagging, regurgitation, or vomiting
  • Cyanosis or collapse in severe cases

For veterinarians: assess for concurrent issues such as gastro-oesophageal reflux disease (GORD) and heat intolerance.

Diagnosis

  • History and physical examination (stertor, narrowed nares)
  • Sedated/oral exam to evaluate palate, tonsils, larynx
  • Imaging (radiographs or CT) to assess trachea and secondary changes
  • BOAS functional grading schemes (Liu et al., 2015)


Treatment

Surgical Options (for veterinarians)

  • Stenotic nares resection (vertical wedge or alapexy)
  • Soft palate resection (staphylectomy/palatoplasty)
  • Removal of everted saccules
  • Permanent tracheostomy for advanced cases

Early intervention before laryngeal collapse significantly improves prognosis (Riecks et al., 2007).

Medical and Owner-Led Management

  • Weight control – obesity worsens BOAS
  • Exercise modification – avoid heat and overexertion
  • Stress minimisation – prevent hyperthermia

Post-op care includes rest, pain relief, and monitoring for swelling.

Prognosis

With timely surgery, most dogs show dramatic improvement in exercise tolerance and quality of life. However, BOAS is lifelong: even after surgery, affected dogs remain heat-sensitive and should not be bred.

Welfare Considerations

BOAS is a recognised welfare issue. Selective breeding for extreme brachycephaly perpetuates disease. Vets should educate owners and breeders on responsible practices (O’Neill et al., 2015).

Key Take-Home Messages for Owners

  • Noisy breathing is not “normal for the breed” – it may be BOAS
  • Early diagnosis and weight control are vital
  • Surgery by an experienced vet surgeon can improve quality of life
  • Dogs with BOAS need extra care in hot weather and under anaesthesia


References

  • Liu, N.C., et al. (2015). Brachycephalic Obstructive Airway Syndrome (BOAS): objective assessment of respiratory function. PLoS ONE, 10(6): e0130741.
  • O’Neill, D.G., et al. (2015). Epidemiological study of BOAS in the UK. Canine Genetics and Epidemiology, 2:10.
  • Poncet, C.M., et al. (2006). Long-term results of upper airway surgery in brachycephalic dogs: 62 cases (1990–2003). JAVMA, 228(9), 1424–1428.
  • Riecks, T.W., et al. (2007). Surgical correction of brachycephalic syndrome in dogs: 62 cases (1991–2004). JAVMA, 230(9), 1324–1328.