A comparison of the effect of propofol and alfaxalone on laryngeal motion in nonbrachycephalic and brachycephalic dogs.

OBJECTIVE: To compare the effect of propofol and alfaxalone on laryngeal motion under a light plane of anaesthesia in nonbrachycephalic and brachycephalic dogs anaesthetized for nonemergency procedures.

STUDY DESIGN: Prospective, randomized clinical trial.

ANIMALS: A total of 48 client-owned dogs (24 nonbrachycephalic and 24 brachycephalic).

METHODS: A standardized premedication of methadone (0.2 mg kg-1 ) and acepromazine (0.01 mg kg-1 ) was administered intramuscularly. Dogs were randomly assigned to be induced with increments of propofol (1-4 mg kg-1 ) or alfaxalone (0.5-2 mg kg-1 ). Laryngeal assessment was performed under a light plane of anaesthesia by a surgeon (GTH) who was unaware of the induction protocol. Laryngeal movement was assessed as either being present when abduction of the laryngeal cartilages upon inspiration was identified, or absent when abduction was not recognized. Simultaneously, a 60-second video was recorded. The same surgeon (GTH) and an additional surgeon (NK) re-evaluated the videos 1 month later. Categorical comparisons were studied using Chi square and Fisher's exact test where appropriate. Pairwise evaluation of agreement between scorers was undertaken with the kappa statistic (κ).

RESULTS: There were no significant differences (p > 0.05) identified between the presence or absence of laryngeal motion between dogs administered propofol or alfaxalone, as well as when analysing nonbrachycephalic and brachycephalic dogs separately. The majority of dogs (>75%) maintained some degree of laryngeal motion with both protocols. Agreement between assessors was excellent (κ = 0.822).

CONCLUSIONS: Alfaxalone maintained laryngeal motion similarly to propofol in nonbrachycephalic and brachycephalic dogs.

CLINICAL RELEVANCE: Both agents would appear appropriate for allowing assessment of laryngeal motion in nonbrachycephalic and brachycephalic dogs. The assessment technique of subjective evaluation of laryngeal motion via peroral laryngoscopy under a light plane of anaesthesia produced consistent results amongst assessors, regardless of the induction agent used.