Cardiopulmonary effects of medetomidine, oxymorphone, or butorphanol in selegiline-treated dogs.
OBJECTIVE
To determine if chronic selegiline HCl administration affects the cardiopulmonary response to medetomidine, oxymorphone, or butorphanol in dogs.


METHODS
Prospective randomized experimental study.


METHODS
Twenty-eight adult, random source, hound dogs weighing 21-33 kg.


METHODS
Dogs were assigned to the following treatment groups: selegiline + medetomidine (MED; n = 6); placebo + MED (n = 6), selegiline + oxymorphone (OXY; n = 6); placebo + OXY (n = 6); selegiline + butorphanol (BUT; n = 7) or placebo + BUT (n = 6). Nine dogs were treated with two of the three pre-medicants. Dogs were treated with selegiline (1 mg kg(-1) PO, q 24 hours) or placebo for at least 44 days prior to pre-medicant administration. On the day of the experiment, arterial blood for blood gas analysis, blood pressure measurements, ECG, cardiac ultrasound (mM-mode, 2-D, and continuous wave Doppler), and behavioral observations were obtained by blinded observers. An IV injection of MED (750 micro g m(-2)), OXY (0.1 mg kg(-1)) or BUT (0.4 mg kg(-1)) was given. Cardiopulmonary and behavioral data were collected at 1, 2, 5, 15, 30, and 60 minutes after injection.


RESULTS
Selegiline did not modify responses to any of the pre-medicant drugs. Medetomidine caused a significant decrease in heart rate (HR), cardiac output (CO), and fractional shortening (FS). Mean arterial pressure (MAP), systemic vascular resistance (SVR), and central venous pressure (CVP) were increased. Level of consciousness and resistance to restraint were both decreased. Oxymorphone did not affect MAP, CO, CVP, or SVR, but RR and PaCO(2) were increased. Level of consciousness and resistance to restraint were decreased. BUT decreased heart rate at 1 and 5 minutes. All other cardiovascular parameters were unchanged. BUT administration was associated with decreased arterial pH and increased PaCO(2). BUT decreased level of consciousness and resistance to restraint.


CONCLUSIONS
Although pre-medicants themselves altered cardiopulmonary and behavioral function, selegiline did not affect the response to medetomidine, oxymorphone, or butorphanol in this group of normal dogs.
Dodam
John R
JR
Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, 379 East Campus Drive, Columbia, MO 65211, USA. dodamj@missouri.edu
Cohn
Leah A
LA
Durham
Harris E
HE
Szladovits
Balazs
B
D000818:Animals; D001784:Blood Gas Analysis / Q000662:veterinary; D002077:Butorphanol / Q000008:administration & dosage / Q000494:pharmacology; D004285:Dogs / Q000502:physiology*; D004338:Drug Combinations; D004562:Electrocardiography / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D006993:Hypnotics and Sedatives / Q000008:administration & dosage / Q000494:pharmacology*; D020926:Medetomidine / Q000008:administration & dosage / Q000494:pharmacology; D008996:Monoamine Oxidase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D010111:Oxymorphone / Q000008:administration & dosage / Q000494:pharmacology; D011229:Preanesthetic Medication / Q000662:veterinary*; D011446:Prospective Studies; D012642:Selegiline / Q000008:administration & dosage / Q000494:pharmacology*
D004338:Drug Combinations; D006993:Hypnotics and Sedatives; D008996:Monoamine Oxidase Inhibitors; D012642:Selegiline; D010111:Oxymorphone; D020926:Medetomidine; D002077:Butorphanol