Babirusa (Babyrousa babyrussa) are endangered wild pigs that naturally inhabit Sulawesi. They weigh up to 90 kg in the wild and adult males have four tusks, of which the maxillary pair grow through the dorsal aspect of the muzzle.4 Although they are bred and maintained as exhibit animals in several zoos there is little published information about their veterinary care.
While many different anesthetic protocols, including barbiturate combinations, dissociatives, opiods, alpha-2 agonists, tiletamine/zolazepam, propofol and multiple different combinations, have been used in domestic and nondomestic swine,1-3,6,8 there are limited published reports of anesthesia in babirusa.1,7 One protocol that has been used in babirusa includes a combination of butorphenol, detomidine and midazolam, all administered i.m.1 There is one published case of tiletamine/zolazepam administered at 5.3 mg/kg to immobilize a babirusa for tusk extraction7 but the quality of anesthesia was not described. In this report we describe an immobilization protocol using premedication with i.m. xylazine (Gemini E, Vetus Animal Health, Burns Veterinary Supply, Rockville Centre, New York USA) and induction with i.m. tiletamine/zolazepam (TZ) (Telazol®, Fort Dodge, Fort Dodge, Iowa USA). Anesthesia was reversed with yohimbine (Antagonil, Wildlife Laboratories, Fort Collins, Colorado USA) and, in most cases, flumazenil (Mazicon, Hoffman-LaRoche Inc., Roche Animal Nutrition and Health, 45 Eisenhower Dr., Paramus, New Jersey USA) both administered either i.v. or i.m.
Fourteen babirusa (five females and nine males, ranging in age from 2–13 yr) were immobilized 24 times during a 3-yr interval. Xylazine (x̄ =1.25±0.33 mg/kg; range: 0.82–2.07 mg/kg) was administered i.m. as a premedication. Initial sedative effects generally occurred within 10 min and consisted of ataxia although some animals were not sedate at 20 min. Degree of sedation varied with some animals becoming recumbent but the majority remaining standing. TZ was given i.m. (x̄ =1.82±0.63 mg/kg; range: 0.86–3.59 mg/kg) 20 min after xylazine and animals became laterally recumbent within 23±9 min (range: 5–41 min) of the xylazine dose. They could be handled within 10 min of the TZ injection.
Babirusa heart rates during anesthesia ranged from 35–88 beats/min (0 = 60 beats/min), respiratory rates ranged from 12–42 breaths/min (x̄ = 24 breaths/min), and temperatures ranged from 34.2–40.3°C. Variations in the heart and respiratory rates were most likely related to the plane of anesthesia.
Anesthesia was reversed with yohimbine (x̄ = 0.15±0.04 mg/kg; range: 0.09–0.24 mg/kg) and, in most cases, flumazenil (1 mg/20 mg zolazepam), both given i.m. or i.v. After yohimbine and flumazenil were given i.m. animals were standing within 25±22 min (range: 2–55 min) compared to 50±31 min (range: 20–122 min) after i.v. administration. The longer time to effect when the drugs were administered i.v. versus i.m. was not expected. The route of administration was dependent upon ease of venipuncture and in some cases limb movement precluded venous access. Thus, animals that received the i.m. doses may have been at a lighter anesthetic plane resulting in shorter recovery times. Alternatively, this may indicate that these drugs are absorbed equally well from an i.m. versus i.v. administration. Yohimbine, however, given i.v. to rocky mountain elk (Cervus elaphus nelsoni) resulted in a recovery time approximately 100 times faster than when the same dose was given i.m.5 In white-tailed deer (Odocoileus virginianus) reversal times were approximately the same when the i.m. dose of yohimbine is double that of the i.v. dose.9 Due to the lack of comparative studies on the efficacy of yohimbine given i.v. versus i.m. in domestic swine, and the different depths of anesthesia when these babirusa were reversed, no conclusions can be drawn regarding the sensitivity of babirusa to this drug, or the difference in absorption between i.v. and i.m. injections.
This protocol is safe, reversible, inexpensive, requires only small dart volumes and results in sedation and muscle relaxation sufficient for minor diagnostic and therapeutic procedures.
We thank the Mammal Department at the Wildlife Conservation Park/Bronx Zoo for assistance with immobilizations. We also thank Hoffman-LaRoche for providing the flumazenil.
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