Comparison of transdermal fentanyl and intramuscular oxymorphone on post-operative behaviour after ovariohysterectomy in dogs.

The effects of transdermal fentanyl and i.m. oxymorphone on behavioural and physiological responses, after ovariohysterectomy in dogs, were investigated. The study involved three groups of 10 dogs: fentanyl/surgery (FS), oxymorphone/surgery (OS), fentanyl/control (FC). A transdermal fentanyl delivery system (50 microg hour(-1)) (FS and FC) was applied 20 hours before surgery, or i.m. oxymorphone (OS) was administered. After ovariohysterectomy (FS and OS) or anaesthesia alone (FC), dogs were continuously videotaped for 24 hours and a standardised hourly interaction with a handler performed. The videotapes were analysed, and interactive and non-interactive behaviours evaluated. In addition, pain and sedation scores, pulse and respiratory rates, rectal temperature, arterial blood pressure, plasma cortisol and plasma fentanyl concentrations were measured. This study showed that transdermal fentanyl and i.m. oxymorphone (0.05 mg kg(-1)) produced comparable analgesic effects over a 24 hour recording period. I.m. oxymorphone produced significantly more sedation and lower rectal temperatures than transdermal fentanyl. There were no significant differences between groups in respiratory and heart rates, and arterial blood pressures.