The Veterinary Record, Vol 138, Issue 1, 11-13
Copyright © 1996 by British Veterinary Association

Cardiopulmonary effects of combinations of medetomidine hydrochloride and atropine sulphate in dogs

¹ Department of Large Animal Medicine and Surgery, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire AL9 7TA

Medetomidine and xylazine are alpha 2 adrenoceptor agaonists which are used as sedatives and premedicants in small animals. However, bradycardia is a side effect and the use of atropine sulphate has been recommended to counteract it. This study investigated the effects of combining medetomidine (40 µg/kg) and atropine (30 µg/kg) on the cardiopulmonary function of six dogs. Medetomidine administered alone caused severe bradycardia, but hypertension was mild and transient.Medetomidine and atropine administered together caused an initial bradycardia, but within 15 minutes there was tachycardia accompanied by a mean arterial blood pressure of 210 mm Hg. When atropine was administered 30 minutes before medetomidine, tachycardia and hypertension were observed within five minutes of the medetomidine injection. Thus, although atropine will counteract medetomidine-induced bradycardia, its use results in prolonged and severe hypertension, in association with the tachycardia. Although atropine may be life-saving when bradycardia is profound, its indiscriminate use in combination with alpha 2 adrenoceptor agonists may be disadvantageous.

This article has been cited by other articles:

				R. K. Alvaides, F. J. T. Neto, A. J. A. Aguiar, D. Campagnol, and P. V. M. Steagall Sedative and cardiorespiratory effects of acepromazine or atropine given before dexmedetomidine in dogs Vet Rec., June 28, 2008; 162(26): 852 - 856. [Abstract] [Full Text] [PDF]