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Brachycephalic Syndrome

Heidi Phillips, VMD, DACVS (Small Animal), University of Illinois

Michelle Jaeger, CVT, VTS (Surgery), University of Illinois

September 2016|Peer Reviewed

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Brachycephalic Syndrome

Brachycephalic syndrome affects dogs with markedly shortened craniofacial conformation and can result in dyspnea, exercise intolerance, collapse, and death if not treated appropriately. Corrective airway surgery is best implemented early in life and can be safely performed in dogs as young as 4 to 6 months.1-8 Delaying surgery can predispose brachycephalic dogs to laryngeal collapse, pneumonia, fibrotic lung conditions, and cardiovascular disease, including heart base tumors.7-10 Older dogs may also have more difficulty recovering from surgery.

Case Summary

Heidi Phillips, VMD, DACVS (Small Animal), University of Illinois

Maggie, an 8-year-old spayed English bulldog with a history of noisy breathing, presented to University of Illinois Veterinary Teaching Hospital because of 2 episodes, within 1 week of each other, of severe respiratory distress requiring emergency sedation. An oral examination by her primary veterinarian showed an elongated soft palate, everted laryngeal saccules, and stenotic nares. Maggie was prescribed prednisone for at-home management and referred for surgical assessment and treatment for brachycephalic syndrome.

Brachycephalic syndrome is a chronic, debilitating, and potentially fatal condition in dog breeds with markedly shortened craniofacial conformation.1-3 (See Table 1.) 


Brachycephalic Dog Breeds3,16

Small Breed Medium-to-Large Breed
Boston terrier Boxer
Brussels griffon Bull mastiff
French bulldog Chinese shar-pei
Lhasa apso Dogue de Bordeaux
Pekingese English bulldog
Shih tzu  

Congenital and acquired deformities result from selection for craniofacial bony shortening without a concomitant reduction in the volume of nasopharyngeal and oropharyngeal soft tissues.3-8 Anatomic abnormalities include stenotic nares, an elongated soft palate, and a hypoplastic trachea, diagnosed in 58% to 85%, 62% to 100%, and 13% of brachycephalic dogs, respectively.9-11 Aberrant rostral and caudal nasopharyngeal turbinates and intranasal mucosal contact points have also been described.12,13 

Most dogs with brachycephalic syndrome have moderate-to-severe upper airway obstruction because of anatomic abnormalities.1 Mild-to-severe respiratory clinical signs predominate and include snoring or stertor, coughing, stridor, inspiratory dyspnea, difficulty eating, exercise intolerance, cyanosis, collapse, syncope, and death.3,7-9 Affected dogs are more likely to experience respiratory signs when stressed or anxious, during exercise or restraint, and in hot weather. Panting caused by overheating can worsen swelling of tissue within the airway. Obesity also contributes to dyspnea in many dogs with brachycephalic syndrome, and an inability to exercise vigorously may predispose these dogs to weight gain.8-9  

Most dogs with brachycephalic syndrome have moderate-to-severe upper airway obstruction because of anatomic abnormalities.

Gastrointestinal disorders such as regurgitation, vomiting, gastritis, duodenitis, hiatal hernia, and aspiration pneumonia can accompany respiratory issues.3,10 Brachycephalic dogs may also be diagnosed with sleep disorders, including sleep apnea, which may be linked to systemic hypertension development.3,10 Cardiopulmonary disorders, including hypoxemia, hypercapnea, bronchial collapse, polycythemia, heatstroke, and hypertension, and neoplastic disorders such as chemodectoma may also be present.2,3,7-10,14

Related Article


Demand for brachycephalic conformation as a breed standard persists despite health issues associated with the anatomic abnormalities.15 The American Kennel Club and Kennel Club of the United Kingdom reported increases of more than 450% in registration of brachycephalic breeds from 2000-2010, indicating a sizable at-risk population.3-4,11,15 


Maggie had a body condition score of 8/9. Physical examination showed stenotic nares. Auscultation of the larynx, trachea, and lung fields disclosed upper airway noise. Routine clinical laboratory tests, including CBC, serum chemistry profile, and urinalysis, were within normal limits. Neck and thoracic radiographs showed a hypoplastic trachea and no signs of underlying cardiac disease or aspiration pneumonia.

Differential diagnoses included brachycephalic syndrome, laryngeal paralysis, upper airway foreign body, neoplasia, and trauma. Following IV administration of butorphanol and propofol, examination of Maggie’s airway disclosed everted, markedly enlarged palatine tonsils (see Figure 1), an elongated soft palate (see Figure 2), and everted laryngeal saccules (see Figure 3). Visual examination of the larynx during inspiration and expiration showed no laryngeal paralysis, but focal contact of the corniculate and cuneiform processes of the arytenoid cartilages on inspiration confirmed mild Stage III laryngeal collapse. The stages are: 

  • Stage I: Everted laryngeal saccules
  • Stage II: Collapse or paradoxical motion of cuneiform processes of the arytenoid cartilages
  • Stage III: Collapse or paradoxical motion of the corniculate processes of the arytenoid cartilages

References and Author Information

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