Retrospective evaluation of xylazine/halothane anesthesia in 125 cattle

A retrospective morbidity and mortality study was carried out on 125 case records of cattle involving xylazine/halothane anesthesia at the Ontario Veterinary College, Guelph between May 1979 and February 1983.One hundred and six animals were given xylazine intramuscularly with a mean dose of 0.22 mg/kg and the remaining 19 were given a mean dose of 0.17 mg/kg intravenously. When the animals became recumbent, they were intubated and connected to an anesthetic machine which delivered halothane in oxygen.Anesthetic complications were recorded for ten cattle (8%) in the series and were mainly associated with regurgitation of ruminal contents, with or without aspiration. Three animals died as a result of the anesthetic procedure and in three other instances there were complications which were potentially fatal. Two of the anesthetic deaths were directly attributable to faulty technique rather than a specific drug response.The use of xylazine/halothane was judged to be clinically satisfactory and did not produce an unacceptable complication rate, although it is evident there is a significant risk associated with general anesthesia in ruminants.