Sedative and cardiovascular effects of romifidine, alone and in combination with butorphanol, in the horse |
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| Authors: | K W Clarke G C W England L Goossens |
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| Institution: | Department of Large Animal Medicine and Surgery, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire, UK;*Boehringer Ingelheim Vetmedica GmbH, P.O. Box 200, D-6507 Ingelheim, Germany. |
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| Abstract: | The behavioural and sedative effects of intravenous (iv) romifidine (40 and 80 μg/kg bodyweight bwt]) alone or in combination with iv butorphanol (50 μg/kg bwt) were investigated in four ponies and one Thoroughbred horse. Apparent sedation, as judged by the lowering of the head, and by the response to imposed touch, visual and sound stimuli was assessed. The combination with butorphanol reduced the animals' response to imposed stimuli when compared with the effect of the same dose of romifidine alone. Following the administration of romifidine/butorphanol combinations muzzle tremor was noted and some animals attempted to walk forward. In a separate series, the cardiopulmonary effects of iv romifidine (80 μg/kg bwt) alone, or in combination with butorphanol (50 μg/kg bwt) were investigated. Romifidine and the romifidine/butorphanol combination caused similar cardiovascular changes, these being bradycardia with heart block, and hypertension followed by hypotension. Romifidine caused a transient decrease in arterial oxygen tensions and arterial carbon dioxide tensions had increased significantly by the end of the 90 min recording period. Romifidine/butorphanol combinations produced significantly higher arterial carbon dioxide tensions during the first 15 mins after drug administration than did romifidine alone. Butorphanol at 50 μg/kg bwt iv reduced the response to imposed stimuli in horses sedated with romifidine. The combination produced no cardiovascular changes beyond those induced by romifidine alone, but did increase the degree of respiratory depression. |
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