Effects of hydromorphone or oxymorphone, with or without acepromazine, on preanesthetic sedation, physiologic values, and histamine release in dogs

Objective-To compare hydromorphone with oxymorphone, with or without acepro mazine, for preanesthetic sedation in dogs and assess changes in plasma con centration of histamine after drug administration. Design-Randomized clinical study. Animals-10 healthy mixed-breed dogs. Procedure-Dogs were treated IM with hydromorphone (group H), oxymorphone (g roup O), hydromorphone with acepromazine (group H/A), or oxymorphone with a cepromazine (group O/A). Sedation score, heart rate, respiratory rate, syst olic blood pressure, and oxygen saturation were recorded at baseline immedi ately after drug administration (T0) and every 5 minutes for 25 minutes (T2 5). Plasma histamine concentration was measured at baseline and T25. Results-Sedation was similar between groups H and O at all times. Sedation was significantly greater for groups H/A and O/A from T10 to T25, compared with other groups. Systolic blood pressure was significantly reduced at T25 in group H/A, compared with group H, and in group O/A, compared with group O. Prevalence of panting at T25 was 50% for groups H and O, compared with 20% for group H/A and 30% for group O/A. By T25, heart rate was significant ly lower in all groups. Oxygen saturation was unaffected by treatment. Mean +/- SD plasma histamine concentration was 1.72 +/- 2.69 ng/ml at baseline and 1.13 +/- 1.18 ng/ml at T25. There was no significant change in plasma h istamine concentration in any group. Conclusions and Clinical Relevance-Hydromorphone is comparable to oxymorpho ne for preanesthetic sedation in dogs. Sedation is enhanced by acepromazine . Neither hydromorphone nor oxymorphone caused an increase in plasma histam ine concentration.