The efficacy and safety of thiafentanil-azaperone for anesthetic induction in captive addax (Addax nasomaculatus) was evaluated. Fifty-seven anesthetic procedures for electroejaculation (EEJ) of seventeen captive addax bulls were performed between May 2018 and February 2019. Addax were darted intramuscularly using thiafentanil (0.035±0.005 mg/kg) and azaperone (0.344±0.043 mg/kg). Induction (2.7±1.7 min) was the time from darting to recumbency. After transportation to the hospital, addax required supplemental ketamine (1.613±0.370 mg/kg administered IV 7.6±3.1 min after recumbency) for intubation, with nine procedures also requiring isoflurane. All animals were anesthetically maintained on isoflurane. Addax were placed in right lateral recumbency for EEJ and sternal recumbency between cycles. Arterial blood samples were collected at 20 and 40 min after darting and analyzed immediately for pH, PaCO2, PaO2, base excess, bicarbonate, oxygen saturation, and lactate values. Physiologic measurements including heart rate, respiratory rate, temperature, indirect blood pressure, ETCO2, and SPO2 were recorded every 10 min. Thiafentanil was antagonized with naltrexone (administered 25% IV and 75% SC) at ten times the thiafentanil dose. Recovery time from reversal to standing was 6.8±4.4 min, and recovery was consistently smooth with minimal ataxia. Adverse cardiopulmonary effects observed were hypercapnia (PaCO2: T=20 51.15±9.75 mm Hg; T=40 51.61±9.02 mm Hg) and respiratory acidosis (pH: T=20 7.341±0.058; T=40 7.339±0.073). Thiafentanil-azaperone proved to be a safe and suitable combination for anesthetic induction of captive addax, and with supplemental maintenance drugs was appropriate for invasive procedures.
The authors thank Allyssa Roberts, LVT, the hoofstock animal care specialists at Fossil Rim Wildlife Center, Dr. Bill Lance, and Wildlife Pharmaceuticals for their assistance with this study.