FIELD ANESTHESIA of FREE RANGING MOUNTAIN GORILLAS (Gorilla Gorilla Beringei) from the VIRUNGA VOLCANO REGION, CENTRAL AFRICA
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FIELD ANESTHESIA OF FREE RANGING MOUNTAIN GORILLAS (Gorilla gorilla beringei) FROM THE VIRUNGA VOLCANO REGION, CENTRAL AFRICA Jonathan M. Sleeman, VetMB, MRCVS,1* Kenneth Cameron, DVM,2 Antoine B. Mudakikwa, DVM,2 Susanne Anderson, BVSc,3 John E. Cooper, FRCVS, Barkley Hastings, DVM (deceased), James W. Foster, DVM (deceased), Elizabeth J. Macfie, DVM,5 and H. Melvin Richardson, DVM6 1Colorado State University, Veterinary Teaching Hospital, Fort Collins, CO 80523 USA; 2Mountain Gorilla Veterinary Center, B.P. 1321, Kigali, Rwanda; 3B.P. 171, Tai, Ivory Coast; 4Wildlife Health Services, PO Box 153 , Wellingborough, Northants NN8 2ZA, UK; 5International Gorilla Conservation Programme, PO Box 10950, Kampala, Uganda; 62519 Broadway #104, San Antonio, TX 78215 USA Abstract The Morris Animal Foundation’s Mountain Gorilla Veterinary Center (formerly the Volcano Veterinary Center) was established in 1986. Since its inception, 26 field anesthesias of mountain gorillas have been performed for either life-threatening problems or severe human-induced disease. The majority of anesthesias (i.e., 18 of 26, or 69%) were performed to remove rope or wire snares from a limb, or to treat snare induced wounds. Table 1 summarizes the anesthetic data available from each procedure. For animals with an actual recorded weight the mean induction dosage of ketamine was 7.1 mg/kg (range: 5.9-8.0 mg/kg; n = 4), a dosage similar to those recommended for western lowland gorillas (Gorilla gorilla gorilla).1 The mean induction time for anesthesias requiring a single initial dose of ketamine was 5.2 min (range: 3-11 min; n = 13). All induction agents were delivered by remote injection using the Telinject® system, and occasionally multiple darting attempts were necessary. Every attempt was made to dart the animal unawares and thus minimize disturbance to the gorillas. All interventions required a team approach with considerable cooperation from the researchers of the Dian Fossey Gorilla Fund’s Karisoke Research Center, the Mountain Gorilla Project and the International Gorilla Conservation Programme. Fundamental to the success of the interventions was the assistance of the park staff and gorilla trackers from the Office Rwandais pour le Tourisme et les Parc Nationaux, the Institut Congolais pour la Conservation de la Nature (formerly the Institut Zairois pour la Conservation de la Nature) and the Karisoke Research Center. In addition, porters were hired to carry the equipment within the forest. The procedures were performed within or in close proximity to the rest of the group of gorillas. Thus, once the animal was anesthetized, a team was assigned to keep the other gorillas away from the patient and create a visual barrier. Only one human injury (a bite wound) has occurred as a result of an anesthesia. More injuries were reported as a result of the physical restraint of gorillas. Occasionally there was moderate disruption to the group with some reaction from other gorillas, in particular, the silverback males but no long term behavioral effects have been noted. No intraspecific aggression was noted during or immediately after the procedures. The intervention team would remain with the gorilla until it was fully recovered and able to rejoin its group. For 1998 PROCEEDINGS AAZV AND AAWV JOINT CONFERENCE 1 gorillas given a single dose of ketamine the mean recovery time was 42 min (range: 5-80 min; n = 9). Four animals did not recover from anesthesia due to the severe nature of their medical conditions. One animal was physically removed from the park and anesthetized at a local human hospital. This individual was not included in this study. LITERATURE CITED 1. Kreeger, T. J. 1996. Handbook of Wildlife Chemical Immobilization. International Wildlife Veterinary Services, Inc. Pp. 165. 2 1998 PROCEEDINGS AAZV AND AAWV JOINT CONFERENCE 1998 PROCEEDINGS AAZV AND AAWV JOINT CONFERENCE 3 4 1998 PROCEEDINGS AAZV AND AAWV JOINT CONFERENCE EVALUATING PUBLISHED IMMOBILIZATION AND ANESTHESIA INFORMATION David B. Brunson, DVM, MS, Dipl ACVA Department of Surgical Sciences, University of Wisconsin, Madison, WI 53706 USA and Safe-Capture International, Inc., Mt. Horeb, WI 53572 USA Abstract Multiple factors must be considered when deciding on a chemical immobilization/anesthetic technique. Novel situations and rare species require technique and drug dosage extrapolation. Critical factors for evaluating published techniques are: individual characteristics of the animal such as age, body composition, level of excitation, and health status. Published dosages must also be interpreted prior to use. This includes determining if the published dosages represent an average of widely variable or precise drug effects. Route of administration, site of injection and the associated time-line are necessary for evaluation of the published technique. Use of validated sources and multiple references coupled with knowledge of the species will result in safe and effective immobilization techniques. Introduction The challenge to find, evaluate and modify immobilization/anesthesia techniques is frequently encountered in zoological medicine. In many cases, finding a reference that matches the proposed capture situation or target species can be difficult. If found, the reference usually is missing pertinent information making it necessary to interpret the procedures used. Additionally, immobilization/anesthesia information will often not be the focus of the article and thus the technique presented will constitute a minor part of the citation. As such, immobilization procedures may not be reviewed for their clarity or content and may even be limited to anecdotal comments. The authors can frequently provide personal experiences that are helpful, providing they can be contacted for advise. These limitations often result in a decision dilemma to either modify a published technique or develop a new immobilization procedure (including drugs and dosages). The goals of immobilization are consistent across species, institutions, clinicians and situations. To reach these goals, the correct drug, dosage, route and delivery technique must be chosen. An understanding of the species and knowledge of the individual animal is important. Currently it is estimated that there are 9-10 million species of animals on the earth of which under 2 million have been characterized. Familial, breed, geographic and genetic differences further increase the variability among animals. When evaluating a recommended immobilization technique, the following factors should be used: individual animal variation, effect of emotional status, dosage recommendation and calculations, conditions of administration, site of injection and pharmacokinetics. This paper will discuss these issues and present approaches to interpretation of immobilization/anesthesia references. 1998 PROCEEDINGS AAZV AND AAWV JOINT CONFERENCE 5 Animal Variation: Physiologic Factors that Affect Animal Response to Anesthetic Drugs Published anesthetic procedures should include information on age, environment, physical condition and excitement level. The response to anesthetic drugs varies with age. Younger animals, in general, require higher dosages. A number of physiologic factors have been associated with this observation. Young animals have a higher metabolic rate. Thus, they absorb, redistribute, excrete and eliminate drugs in a shorter time period. Establishing and maintaining an effective blood concentration requires higher dosages and more frequent redosing. Multiple factors result in older animals requiring lower dosages of anesthetics when compared to young animals. These include lower metabolic activity, a higher percentage of body weight as fat and a lower capacity to distribute drugs out of the CNS and blood. Adipose tissue has a low blood supply in comparison to muscle. Thus, anesthetics are slow to redistribute to this tissue resulting in more drug remaining in the blood. In addition, drugs have a slower elimination from fat storage causing the recovery phase to be prolonged in the older animal. Also keep in mind that very young (newborn) and geriatric animals require lower dosages than other age groups. The season of the year will affect the dosage of the immobilization drug. This is related to the physical activity of the animal, nutritional status and reproductive activities. Wild animals have seasonal variations in the amount of exercise. Spring or fall migrations are associated with marked increases in energy utilization and muscle activity. Nutritional status changes in relationship to food availability and food type. Physical condition has also been shown to affect animals ability to handle stress. In one study, sedentary sheep were less tolerant to heat stress than were physically fit animals. Many captive and non-predatory species are not highly fit. The presence of infections or infestations will also lower animal tolerance to handling or capture. Bears with heavy layers of fat prior to hibernation must be treated differently than animals emerging from their den in the spring. Reproductive activities affect the mental status as well as the nutritional plane of the animal. Breeding and sparring in some species such as moose, leave the dominant bull nutritionally drained by the end of the rut. Appropriate immobilization at this time will require greater precision in selecting the correct dosage and providing necessary support than would be required in the late summer. Evaluate immobilization sources to identify factors such as the hair coat thickness,