Severity of nasopharyngeal collapse before and after corrective upper airway surgery in brachycephalic dogs.

Abstract

To determine the severity of nasopharyngeal collapse in brachycephalic dogs before and after corrective airway surgery. Twenty-three brachycephalic dogs (21 with clinical signs referrable to the upper airway) and nine clinically normal nonbrachycephalic dogs (controls). Dogs were evaluated with fluoroscopy awake and standing with the head in a neutral position. The magnitude of nasopharyngeal collapse was measured as the maximum reduction in the dorsoventral dimension of the nasopharynx during respiration and expressed as a percentage. Brachycephalic dogs were anesthetized, the airway evaluated, and corrective upper airway surgery (alaplasty, staphylectomy, sacculectomy, tonsillectomy) was performed. A cohort (n=11) of the surgically treated brachycephalic dogs had fluoroscopy repeated a minimum of 6 weeks after surgery. Median preoperative reduction in the dorsoventral dimensions of the nasopharynx was greater in brachycephalic dogs (65%; range: 8-100%) than in controls (10%; range: 1-24%, p=.0001). Surgery did not improve the reduction in dorsoventral diameter of the nasopharynx during respiration in brachycephalic dogs (n=11) postoperatively (p=.0505). Nasopharyngeal collapse was a common and sometimes severe component of brachycephalic airway obstruction syndrome in the cohort of dogs evaluated. The lack of significant postoperative improvement may represent a type II error, a failure to adequately address anatomical abnormalities that increase resistance to airflow, or inadequate upper airway dilator muscle function in some brachycephalic dogs.