Upper-airway obstruction and prolonged recovery from anesthesia following intranasal clotrimazole administration

A 16-month-old Labrador retriever was presented for evaluation and treatment of nasal aspergillosis. Intranasal clotrimazole was administered to treat the condition. The dog was anesthetized on two occasions to facilitate drug administration. Following the first treatment, the dog developed mild pharyngitis but no other complications. Inflammation and edema of the pharynx resulted in upper-airway obstruction following the second treatment. Pentobarbital sedation was used to maintain the endotracheal tube until the obstruction was relieved. Recovery following sedation was extremely prolonged. This case illustrates two adverse drug reactions: severe pharyngitis and edema (probably a result of the vehicles present in the clotrimazole formulation) and prolonged recovery (possibly the result of microsomal enzyme inhibition by the clotrimazole).