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Abstract

Comparison of injectable anesthetics in donkeys

E.V. Taylor; N.S. Matthews, DVM; T.S. Taylor, DVM; K.S. Barling, DVM, PhD

 Objective- To compare induction, anesthesia and recovery of three combinations of guaifenesin-ketamine-xylazine (GKX).

Animals- Five standard donkeys (2 jennies, 3 gelding) weighing 219 to 334 kg.

Procedure-Donkeys were anesthetized 3 times with: ketamine (1500 mg) and xylazine (500 mg) in 1 L of 5% guaifenesin solution (GKX-1), ketamine (2000 mg) and xylazine (500 mg) in 1 L of 5% guaifenesin solution (GKX-2) and ketamine (2000 mg) and xylazine (750 mg) in 1 L of 5% guaifenesin solution (GKX-3).  Each animal was given each combination at 7 day intervals.  Donkeys were sedated with xylazine (1.1 mg/kg bwt) and anesthesia was induced using GKX-1, GKX-2 or GKX-3.  Amount of GKX to recumbency and time to lateral recombency were recorded; anesthesia was maintained with GKX drip for 45 minutes, during which time temperature, respiratory rate, heart rate, oxygen saturation, PaO2, PaCO2 and pH were measured at 0, 5, 15, 30 and 45 minutes.  A noxious stimulus was administered at 5 minute intervals beginning at recumbency and continuing until animals responded.

Results- Mean amounts of GKX-1, GKX-2, and GKX-3 (±SD) to lateral recumbency were .59 (.12), .57 (.18), and .664 (.12) ml/kg bwt.  There was no significant difference between combinations over time for temperature, respiratory rate, heart rate, PaO2 or pH.  At 30 and 45 min., GKX-3 had significantly (P<0.05) lower PaO2 values than GKX-1 and GKX-2.  Mean times to sternal with GKX-1, GKX-2, GKX-3 (±SD) were 22.98 (4.45), 24.56 (4.93), and 28.65 (13.61) minutes, respectively while mean time to standing for GKX-1, GKX-2, and GKX-3 (±SD) were 30.86 (4.95), 31.42 (5.04) and 35.26 (14.36) minutes. Noxious stimulus did not elicit a response in any combination for the 45 minutes animals received the infusion.

Conclusions- GKX-3 is not recommended for field use in donkeys due to respiratory depression seen in this study.  While animals under GKX-1 anesthesia did no respond to the painful stimulus, more voluntary movement was apparent than those under GKX-2.  GKX-2 produced satisfactory depth and duration of anesthesia without significant respiratory depression.

Clinical Significance- GKX-2 combination should produce safe and effective anesthesia donkeys under field conditions.