Comparison of two injectable immobilization combinations in Himalayan tahr (Hemitragus jemlahicus): medetomidine, ketamine, and atipamezole versus carfentanil, xylazine, naltrexone, and atipamezole.

A crossover study was performed in 12 Himalayan tahr (Hemitragus jemlahicus) undergoing preshipment examinations to compare a partially reversible to a fully reversible intramuscular chemical immobilization protocol. The partially reversible protocol (MKA) consisted of induction with medetomidine (0.06 +/- 0.009 mg/kg) and ketamine (2.03 +/- 0.315 mg/kg) and antagonism by atipamezole (0.30 +/- 0.044 mg/kg). The fully reversible protocol (CXNA) consisted of induction with carfentanil (0.009 +/- 0.003 mg/kg) and xylazine (0.08 +/- 0.019 mg/kg) and antagonism by naltrexone (0.867 +/- 0.332 mg/kg) and atipamezole (0.105 +/- 0.023 mg/ kg). Animals were monitored for quality and length of induction and recovery, depth of immobilization, heart rate, respiratory rate, rectal temperature, indirect mean blood pressure (MBP), oxygen saturation, and end-tidal carbon dioxide concentration. Blood was collected for serum cortisol measurement. Significant (P < 0.05) differences included a higher MBP, higher serum cortisol, and longer recovery time with MKA compared to CXNA. In addition, the quality of induction and recovery were different. With MKA, animals ambulated less during induction, remained recumbent longer during recovery, and demonstrated more ataxia on rising. Despite differences between the protocols, both provided an acceptable level of immobilization for pre-shipment testing to be done and appeared to be safe in the study population. These differences should be taken into consideration when selecting the anesthetic protocol because either regimen may be more or less desirable for different medical or immobilization settings.