The use of etorphine-acepromazine (analgesic-tranquillizer) mixtures in horses
Jenkins, J.T.; Crooks, J.L.; Blaine, G.F.; Ling, C.M.
Veterinary Record 90(8): 207-210
1972
ISSN/ISBN: 0042-4900 PMID: 5014727 Document Number: 54258
An immobilization technique was tested over a period of two years on 81 horses requiring minor surgery. The neuro-leptanalgesic mixture (0.5 ml/cwt) was injected in the neck muscle. With a concentration of 1.5 mg/ml etorphine and 10 mg/ml acepromazine, the average time for immobilization was 4.6 min. The success rate was: 60% of cases 'good-excellent' and 28% 'satisfactory', but a few animals had to be given a further half-dose to obtain recumbency. When the etorphine conc. was increased to 2.25 mg/ml, the time for immobilization fell to 3.4 min. (average), pre-immobilization excitement was reduced, and the success rating was better. When the acepromazine conc. was simultaneously increased to 20 mg/ml, time for immobilization was again reduced slightly, but degree of relaxation and side effects were not changed. Peak effect was 10 min. after injection. Urination and defaecation seldom occurred, but muscle tremor occurred in 80% of cases, and was sometimes severe enough to cause sweating and to hinder surgery. Respiration was depressed, but without cyanosis; and there was a tachycardia. The injection has subsequently been given in the jugular vein, and immobilization times of less than one minute have been obtained. The antagonist diprenorphine (0.5 ml/cwt) was given i/v. The conc. was increased from 2 to 3 mg/ml to hasten recovery. Time to walk was generally 1-3 min., and there were no ill effects. However, sedation often persisted, and in severe cases of incoordination a further dose of antagonist was given.