Thiafentanil oxalate (A3080) is a synthetic opioid useful for immobilization of non-domestic hoofstock.1-4 This study compared the combination of thiafentanil oxalate (Wildlife Pharmaceuticals Inc., Fort Collins, Colorado 80524, USA), medetomidine (Zoo Pharm, Laramie, Wyoming 82070, USA), and ketamine (Congaree Veterinary Pharmacy, Cayce, South Carolina, USA) to a combination of medetomidine and ketamine for immobilization of 17 captive axis deer (Axis axis) undergoing vasectomy. Nine deer were administered thiafentanil (0.01±0.003 mg/kg), medetomidine (0.09±0.02 mg/kg), and ketamine (1.36±0.33 mg/kg) (TMK). Eight deer were administered medetomidine (0.09±0.02 mg/kg) and ketamine (3.48±0.55 mg/kg) (MK). Induction time, arterial blood gas, heart rate, respiratory rate, and blood pressure values were monitored and statistically compared. Animals receiving TMK were reversed with naltrexone (Trexonil, Wildlife Pharmaceuticals Inc.) (100 mg/mg thiafentanil) and atipamazole (Antisedan, Pfizer Animal Health, Exton, Pennsylvania 19341, USA) (5 mg/mg medetomidine). Animals receiving MK were reversed with atipamazole (5 mg/mg medetomidine). Mean induction time was 3.5±2.0 min in the TMK group, and 9.8±6.7 min in the MK group. Animals anesthetized with TMK experienced unpredictable inductions, apnea, muscle rigidity, limb movement, and marked respiratory and lactic acidosis. Six of nine animals immobilized with TMK required intubation. Mean blood pressure values were 98±15.2 mm Hg in the TMK, and 124±26.2 mm Hg in the MK groups. MK resulted in smoother inductions, better respiratory function, and less adverse metabolic disturbances, and thus was considered superior to TMK for anesthesia in axis deer.
We thank the staffs of the Bronx Zoo’s Departments of Clinical Care and Mammalogy. We also thank Bill Lance of Wildlife Pharmaceuticals for his advice and for the thiafentanil used in this study.
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