Assessment of hydromorphone and dexmedetomidine for emesis induction in cats

Objective To compare the efficacy of hydromorphone and dexmedetomidine at inducing emesis in cats. Design Prospective, blinded, randomized crossover study. Setting Veterinary university teaching hospital. Animals 12 healthy purpose-bred cats. Interventions Cats were randomly assigned to receive hydromorphone (0.1 mg/kg, subcutaneously) or dexmedetomidine (7 mu g/kg, IM). Following administration, the incidences of emesis, number of emetic events, signs of nausea (hypersalivation, lip licking), temperature, heart rate, respiratory rate, and sedation score were recorded for 6 hours. Measurements and Main Results Emesis was successful in 9 of 12 (75%) cats when treated with hydromorphone and in 7 of 12 (58%) cats when treated with dexmedetomidine (P = 0.67). Dexmedetomidine was more likely to cause sedation than hydromorphone (P < 0.001). Heart rate in cats was significantly decreased at 1 and 2 hours post-hydromorphone (P = 0.003, 0.014, respectively) and at 1, 2, 3, 5, 6 hours post-dexmedetomidine (P = 0.001, 0.003, 0.038, 0.013, 0.001, respectively). Cats were more likely to develop an increase in body temperature with hydromorphone administration although this was not clinically significant. Conclusions Results of the present study indicate that hydromorphone is an effective alternative to dexmedetomidine for the induction of emesis in cats. Hydromorphone appears to cause less sedation and less decrease in heart rate. Further investigation into the most adequate dose of hydromorphone for optimizing emesis is warranted.