Effect of low-dose butorphanol on halothane minimum alveolar concentration in ponies

Authors

  • NORA S. MATTHEWS,

    1. Department of Large Animal Medicine and Surgery, The Texas Veterinary Medical Center, College of Veterinary Medicine, Texas A&M University, College Station, Texas 77843, USA.
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  • S. L. LINDSAY

    1. Department of Large Animal Medicine and Surgery, The Texas Veterinary Medical Center, College of Veterinary Medicine, Texas A&M University, College Station, Texas 77843, USA.
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    • *

      Tropicana Animal Hospital, Las Vegas, Nevada 89119, USA.


Summary

Minimum alveolar concentration (MAC) for halothane was measured before and after administration of intravenous butorphanol (0.022 and 0.044 mg/kg in bodyweight in nine yearling Shetland ponies. Arterial blood pressure, heart rate, respiratory rate, expired CO2 and rectal temperature was also measured. Even though mean MAC values decreased 10 and 9 per cent after the low and high doses respectively, they were not statistically different from those measured prior to butorphanol. Halothane MAC values increased after butorphanol in two ponies, both animals increasing locomotor activity and demonstrating apparent central nervous system stimulation. No significant differences were seen in any variable measured after butorphanol administration.

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