ANESTHESIA OF WILD RED HOWLER MONKEYS (ALOUATTA-SENICULUS) WITH MEDETOMIDINE KETAMINE AND REVERSAL BY ATIPAMEZOLE/

Wild red howler monkeys (Alouatta seniculus) were translocated during the flooding of the forest at a hydroelectric dam site in French Guian a. For a variety of minor clinical procedures, 96 monkeys were anesthe tized with various intramuscular injections of combinations of medetom idine and ketamine. The howler population was composed of healthy anim als (42 males and 54 females) of various ages. Medetomidine (150 mu g/ kg) associated with ketamine (4 mg/kg) gave the best results and was u sed on 63 animals. The injection rapidly resulted in complete immobili zation with good to excellent myorelaxation. The induction stage was q uiet, with absence of both corneal and pedal withdrawal reflexes in 57 animals after 2.9 +/- 1.4 min. Six animals required an additional inj ection. Rectal temperature and respiratory and heart rates decreased d uring anesthesia, whereas relative oxyhemoglobin saturation increased. One death occurred during anesthesia. One abortion and one death also occurred the day following anesthesia but were more probably a result of capture stress. Atipamezole given i.m. at a dose of five times the medetomidine dose 38.4 +/- 8.0 min after the anesthetic injection led to standing recovery in 7.1 +/- 4.5 min. Spontaneous recovery occurre d in 17 animals before the atipamezole injection after an average of 3 0.6 +/- 9.6 min. Total recovery time was shorter in young animals. Med etomidine/ketamine induced good myorelaxation and provided considerabl y shortened immobilization duration, which are two notable advantages for field studies. We recommend this association for short procedures including minor surgery in red howler monkeys. Am. J. Primatol. 45:399 -410, 1998. (C) 1998 Wiley-Liss, Inc.