title: Evaluation of xylazine and ketamine hydrochloride for anesthesia in horses.
abstract: The cardiopulmonary effects resulting from the combination of xylazine and ketamine hydrochloride were evaluated in the adult horse. Xylazine (1.1 mg mg/kg) administered intravenously prior to or simultaneously with ketamine hydrochloride (2.2 mg/kg; intravenous) provided excellent analgesia and light anesthesia in all horses. Cardiac output, arterial blood pressure, pulmonary arterial pressure, central venous pressure, and pulmonary arterial wedge pressure remained within normal limits for the adult horse. Evidence of respiratory acidosis developed with time during the anesthetic period. Induction and recovery from anesthesia appeared smooth and excitement-free. In the horse, larger dosages of ketamine hydrochloride (6.6 mg/kg) following sedation with xylazine (1.1 mg/kg; intravenous) were accompanied by muscular tremor and rigidity, mydriasis, oculogyric movements, sweating, hypertension, tachycardia, and increased rectal temperature during recovery from anesthesia. Providing there is good sedation from xylazine, the combination of xylazine and ketamine hydrochloride as a short-term intravenous anesthetic technique in the horse appears safe and acceptable providing reasonably stable cardiopulmonary function. If the sedative properties of xylazine are not apparent or if excessive dosages of ketamine hydrochloride are used, the drug combination results in serious side effects precluding its use for anesthesia in the horse.
mesh_terms: D000698:Analgesia / Q000662:veterinary; D000771:Anesthesia, Intravenous / Q000662:veterinary*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002245:Carbon Dioxide / Q000097:blood; D002302:Cardiac Output / Q000187:drug effects; D005260:Female; D006327:Heart Block / Q000662:veterinary; D006339:Heart Rate / Q000187:drug effects; D006734:Horse Diseases / Q000139:chemically induced; D006736:Horses / Q000502:physiology; D007649:Ketamine / Q000009:adverse effects / Q000494:pharmacology; D008297:Male; D011651:Pulmonary Artery / Q000187:drug effects; D012119:Respiration / Q000187:drug effects; D013035:Spasm / Q000662:veterinary; D013843:Thiazines; D014991:Xylazine / Q000009:adverse effects / Q000494:pharmacology
chemical_list: D013843:Thiazines; D002245:Carbon Dioxide; D014991:Xylazine; D007649:Ketamine