Twenty-two pet dogs presented to the North Carolina State University Veterinary Teaching Hospital for elective ovariohysterectomy were treated with oxymorphone 2.5 mg/msuperscript 2 (Surgery-O group, 11 dogs) or placebo (Surgery-P group, 11 dogs) immediately before the induction of anaesthesia and 6, 12 and 18 h later. 17 random source dogs assigned to a control group that underwent anaesthesia alone for 2 h received identical treatment with oxymorphone (Control-O group, 9 dogs) or placebo (Control-P group, 8 dogs). The heart rate, respiratory rate, temperature and blood pressure were measured preoperatively, at the time of skin incision (or 1 h after anaesthetic induction of controls), at extubation and at 1, 3, 6, 12 and 24 h after extubation. Plasma cortisol concentration was measured preoperatively, at extubation and at 3, 6 and 12 h. Treatment with oxymorphone reduced the heart rate and body temperature in both the Surgery-O and Control-O groups, but no differences in physical findings suggesting an analgesic effect of the drug were identified. Elevated plasma cortisol concentrations were found at 3 and 6 h after extubation in both surgery groups, whereas the plasma cortisol concentration in the control groups did not change. The plasma cortisol concentration was reduced in the Surgery-O group compared to the Surgery-P group at 3-12 h, suggesting an analgesic effect of the drug. It is concluded that routinely monitored physiological signs are not sensitive indicators of a stress response to ovariohysterectomy, or of an analgesic effect of oxymorphone.
|Publication Title||Applied Animal Behaviour Science|
|Author Address||North Carolina State University, College of Veterinary Medicine, 4700 Hillsborough Street, Raleigh, NC 27606, USA.|
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