Seven captive adult male guanacos (Lama guanicoe) weighing 112.0 +/- 10.9 kg (mean +/- standard deviation) were anesthetized with a combination of medetomidine (90.0 +/- 8.8 microg/kg), ketamine (2.7 +/- 0.3 mg/kg), and butorphanol (0.3 +/- 0.03 mg/kg) administered intramuscularly to evaluate its anesthetic and cardiopulmonary effects. Inductions were smooth and rapid, with a mean time to initial effect of 3 +/- 1.5 min and a mean time to recumbency of 5.1 +/- 3.1 min. Anesthesia was predictable, smooth, and characterized by excellent muscle relaxation. Spontaneous ventilation was maintained throughout anesthesia in all animals. Marked bradycardia ranging from 24 to 52 beats/min was noted across all time points for all individuals. Median heart rates decreased during the procedures, but median heart rate, temperature, respiratory rate, and end-tidal carbon dioxide values over the 20 min monitoring period were not significantly different. Mean arterial partial pressure of oxygen (PaO2) on initial sampling was 65.9 +/- 14.8 mm Hg, with six of seven animals exhibiting hypoxemia (PaO2 <80 mm Hg). After oxygen supplementation for 20 min, mean PaO2 values showed statistically significant increases to a mean value of 127.7 +/- 32.4 mm Hg (P = 0.0014). Mean arterial partial pressure of carbon dioxide (PaCO2) showed a significant increase over the monitoring period (P = 0.0004), and mild hypoventilation (PaCO2 >45 mm Hg) was noted in four animals. Mean total duration of procedure time was 23.3 +/- 3.3 min. All guanacos received 0.45 +/- 0.04 mg/kg atipamezole and 2.7 +/- 0.25 mg/kg naltrexone administered intramuscularly for anesthetic antagonism. Recoveries were smooth and uncomplicated. Mean time to sternal recumbency after antagonist administration was 7.7 +/- 4.5 min, and time to successful standing was 12.9 +/- 5.0 min, with all animals standing on first attempt.

Herds of blackbuck antelope (Antilopa cervicapra) and barasingha (Cervus duvauceli), axis (Cervus axis), sambar (Cervus unicolor), and Formosan sika (Cervus nippon taiwanaus) deer at the Wildlife Conservation Society/Bronx Zoo (WCS/BZ) were fed melengestrol acetate (MGA) at a concentration of 0.000154% in pelleted feed for various periods of times during 1991-2001. The target dose per animal of MGA was 1-2 mg per day. Contraceptive rates during treatment were 100% for blackbuck antelope and barasingha, sambar, and sika deer, and approximately 93% for axis deer. There were no observed adverse effects from MGA treatment on gestation. Post-treatment reproductive rates were lower than pretreatment rates.

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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.