Cardiorespiratory responses and plasma cortisol concentrations in dogs treated with medetomidine before undergoing ovariohysterectomy.
OBJECTIVE
To evaluate effects of medetomidine on anesthetic dose requirements, cardiorespiratory variables, plasma cortisol concentrations, and behavioral pain scores in dogs undergoing ovariohysterectomy.


METHODS
Randomized, prospective study.


METHODS
12 healthy Walker-type hound dogs.


METHODS
Dogs received medetomidine (40 micrograms/kg [18.2 micrograms/lb] of body weight, i.m.; n = 6) or saline (0.9% NaCl) solution (1 ml, i.m.; 6) prior to anesthesia induction with thiopental; thiopental dose needed for endotracheal intubation was compared between groups. Ovariohysterectomy was performed during halothane anesthesia. Blood samples were obtained at various times before drug administration until 300 minutes after extubation. Various physiologic measurements and end-tidal halothane concentrations were recorded.


RESULTS
In medetomidine-treated dogs, heart rate was significantly lower than in controls, and blood pressure did not change significantly from baseline. Plasma cortisol concentrations did not increase significantly until 60 minutes after extubation in medetomidine-treated dogs, whereas values in control dogs were increased from time of surgery until the end of the recording period. Control dogs had higher pain scores than treated dogs from extubation until the end of the recording period.


CONCLUSIONS
Administration of medetomidine reduced dose requirements for thiopental and halothane and provided postoperative analgesia up to 90 minutes after extubation. Dogs undergoing ovariohysterectomy by use of thiopental induction and halothane anesthesia benefit from analgesia induced by medetomidine administered prior to anesthesia induction. Additional analgesia is appropriate 60 minutes after extubation.
Ko
J C
JC
Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater 74078, USA.
Mandsager
R E
RE
Lange
D N
DN
Fox
S M
SM
D000316:Adrenergic alpha-Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D018712:Analgesics, Non-Narcotic / Q000008:administration & dosage / Q000494:pharmacology; D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous / Q000008:administration & dosage; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001831:Body Temperature / Q000187:drug effects; D004285:Dogs / Q000502:physiology* / Q000601:surgery; D004305:Dose-Response Relationship, Drug; D005260:Female; D006221:Halothane; D006339:Heart Rate / Q000187:drug effects; D006854:Hydrocortisone / Q000097:blood*; D006993:Hypnotics and Sedatives / Q000008:administration & dosage / Q000494:pharmacology; D007044:Hysterectomy / Q000662:veterinary; D020926:Medetomidine / Q000008:administration & dosage / Q000494:pharmacology*; D010052:Ovariectomy / Q000662:veterinary; D010149:Postoperative Pain / Q000517:prevention & control / Q000662:veterinary; D011229:Preanesthetic Medication / Q000662:veterinary*; D011446:Prospective Studies; D012119:Respiration / Q000187:drug effects; D013874:Thiopental / Q000008:administration & dosage; D013997:Time Factors
D000316:Adrenergic alpha-Agonists; D018712:Analgesics, Non-Narcotic; D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D006993:Hypnotics and Sedatives; D013874:Thiopental; D020926:Medetomidine; D006221:Halothane; D006854:Hydrocortisone