Chemical Immobilization for Elephants
There has been an increased interest in the captive propagation of elephants and other large exotic animals in recent years, largely for reasons of conservation. As a result, more and more zoos and wildlife preserves are keeping, or anticipate holding, herds of breeding elephants.1 Additionally, there is a growing elephant problem in countries such as Sri Lanka and Malaysia, primarily due to rapid agricultural development,2 although shrinking habitats and an increase in human populations also contribute to this problem. Conflicts between humans and elephants have become common in these areas, occasionally resulting in serious injury or death to humans and elephants alike. Further, the severe threat of extinction of certain wildlife species has alarmed wildlife biologists and conservationists, with many conservation efforts now being attempted to preserve these species and their ecosystems.
All of the above have necessitated a more widespread use of wildlife capture and immobilization protocols in these areas. Generally, the reasons for wildlife captures vary from marking, collaring (with a tracking device), disease surveillance, translocations related to conservation or commercial purposes, treating injuries and taking samples for research. In the above cases, translocations for conservation and safety are the prevailing motivations for the chemical immobilization of elephants, although the protocols and procedures discussed here are also applicable in the case of captive elephants.
Techniques and Procedures
Wildlife capture is a complex event that must be carefully planned. In the case of wild (versus captive) animals, objective information about movement patterns and numbers of animals is needed for population management;1 information gleaned from captured wildlife has played an extremely important role in health research for all wildlife species. The animal species, previous research, equipment used and procedures that will be performed during the capture are some of the key factors determining the type and length of anesthesia needed, and therefore the specific drug or drug combination preferred.
Concerns among clinicians and researchers regarding restraint techniques, equipment and immobilization drugs have led to significant improvements in wildlife veterinary practices in recent decades. This progress, coupled with the experience of practitioners, has contributed to safer practices for both animals and people involved.
In the case of large and potentially dangerous animals such as elephants, chemical immobilization is usually done via remote delivery. A large variety of drugs and drug combinations are used for wildlife captures; in recent years, there has been a great deal of improvement in the efficacy of immobilizing drugs and drug formulations, in part owing to the advent of custom veterinary compounding pharmacies.
In the case of wildlife captures, two terms are usually discussed: immobilization and anesthesia. An immobilized animal is restricted from response or movement through the use of physical restraint or immobilizing drugs. General anesthesia is a drug-induced state characterized by suppressed reflexes and loss of consciousness of the animal. Certain drugs can be used to create anxiolytic (calming), sedative (mental calming) or narcotic (opioid analgesics induced sedation) effects.2 Such medications may also create a smoother induction, maintenance or recovery from general anesthesia.1,2 There are also capture-related challenges and risks that exist for both animals and humans in these instances. In the field, unexpected events such as sudden weather changes, injuries, failures of equipment, drug complications or accidental exposures, abrupt physiological reactions or getting infected by a pathogen from another species, can occur.
Given the increased interest in captive elephants, many zoos have opted to handle these animals using protected or semi-protected contact.1 Both of these systems necessitate the chemical restraint of elephants for husbandry and medical procedures. The literature suggests that many of these procedures can be performed without the need for lateral recumbency, despite relatively little having been written regarding the standing sedation or tranquilization of elephants.2
Chemical or Physical Restraint?
When applied correctly and with due precaution, chemical restraint is a safe and effective capture method for elephants, both captive and in the wild. The chemical restraint of elephants is advantageous over physical capture because:
- It avoids the potential pitfalls (e.g., injury to the animal) posed by snares and traps
- It allows for a more comprehensive examination of the animal
- It facilitates the restraint of selected animals within a group of animals
- The equipment required for chemical restraint is easy to transport in the field
That said, chemical capture can have disadvantages, such as the occasional failure of equipment on site, undesirable side effects of drugs being used or the improper darting of an animal, among others. Nevertheless, chemical restraint has become an indispensible tool in wildlife health, research and management since it facilitates the handling of animals when needed for medical procedures.
Modern capture methods typically require a fairly high degree of expertise and experience, as well as knowledge of the physiology and behavior of the animal being immobilized. Unfortunately, one of the biggest challenges facing wildlife veterinarians in less developed nations (e.g., India, Sri Lanka, Malaysia) is a lack of expertise and experience in wildlife handling and knowledge of the basic physiology of various species. This places a significant demand on wildlife veterinarians in these areas as compared to Australia, the U.K. or the U.S. In order to minimize risks of anesthesia to targeted animals, veterinarians need to be able to impart procedural knowledge to support staff, and react appropriately using the correct equipment with sufficient skill to deal with things that might go wrong during the procedure.2
Drugs for the Immobilization of Elephants
Intramuscular azaperone has been used to tranquilize both Indian and African elephants, both singly and in combination with local anesthesia (lidocaine blocks). In these cases, dosages for azaperone alone range from 0.056-0.107 mg/kg, with a median dosage of 0.08 mg/kg.4 Intramuscular azaperone in combination with butorphanol has also been used with slightly greater dosages of azaperone, yielding generally good results.
In Dr. Neiffer’s study, xylazine was used alone to sedate female elephants to load into a trailer. “Each animal was walked approximately 50 meters and stepped onto a trailer. These procedures were successful (the animals were ultimately loaded) but each sedation was rated fair.”4 In the same study, xylazine in combination with butorphanol was used to sedate male African elephants. This immobilization was rated excellent, but the animals appeared to develop decreased sensitivity to the drugs over time. Yohimbine was used to reverse the effects of xylazine in this study, with naloxone being used to reverse the effects of butorphanol.
Chemical Immobilization of Wild and Exotic Animals (Nielsen, 1999) recommends etorphine combined with carfentanil for the immobilization of African and Asiatic elephants.5 Etorphine is a semi-synthetic opioid possessing an analgesic potency approximately 1,000–3,000 times that of morphine.6 Carfentanil is an analogue of the synthetic opioid analgesic fentanyl, and is one of the most potent opioids available.
1Kock RA, P Morkel, MD Kock. 1993. Current immobilization procedures used in elephants. In: Fowler, M.E. (ed.). Zoo and Wildlife Medicine, Current Therapy 3. W.B. Saunders Co., Philadelphia, Pennsylvania. Pp. 436-441.
2Jainudeen, M. R. (1970): The use of etorphine hydrochloride for restraint of a domesticated Elephant (Elephas maximus). J. Am. vet.med. Ass. 157:624=626.
3Sontakke, Sadanand & Umapathy, Govindhaswamy & Kumar, Devender & Singh, DN. (2017). A manual on Chemical Immobilization of wild animals.
4Neiffer DL, Miller MA, Weber M, Stetter M, Fontenot DK, Robbins PK, Pye GW. Standing sedation in African elephants (Loxodonta africana) using detomidine-butorphanol combinations. J Zoo Wildl Med. 2005 Jun;36(2):250-6. doi: 10.1638/04-013.1. PMID: 17323566.
5Nielsen, L. Chemical Immobilization of Wild and Exotic Animals. Ames : Iowa State University Press, 1999.
6Bentley KW, Hardy DG (June 1967). Novel analgesics and molecular rearrangements in the morphine-thebaine group. 3. Alcohols of the 6,14-endo-ethenotetrahydrooripavine series and derived analogs of N-allylnormorphine and -norcodeine. J. Am. Chem. Soc. 89 (13): 3281–92.
About NexGen Pharmaceuticals
NexGen Pharmaceuticals is an industry-leading veterinary compounding pharmacy, offering sterile and non-sterile compounding services nationwide. Unlike other veterinary compounding pharmacies, NexGen focuses on drugs that are difficult to find or are no longer available due to manufacturer discontinuance or have yet to be offered commercially for veterinary applications, but which still serve a critical need for our customers. We also specialize in wildlife pharmaceuticals, including sedatives and their antagonists, offering many unique options to serve a wide array of zoo animal and wildlife immobilization and anesthesia requirements.
Our pharmacists are also encouraged to develop strong working relationships with our veterinarians in order to better care for veterinary patients. Such relationships foster an ever-increasing knowledge base upon which pharmacists and veterinarians can draw, making both significantly more effective in their professional roles.
Disclaimer
The information contained in this blog post is general in nature and is intended for use as an informational aid. It does not cover all possible uses, actions, precautions, side effects, or interactions of the medications shown, nor is the information intended as medical advice or diagnosis for individual health problems or for making an evaluation as to the risks and benefits of using a particular medication. You should consult your veterinarian about diagnosis and treatment of any health problems. Information and statements have not been evaluated by the Food and Drug Administration ("FDA"), nor has the FDA approved the medications to diagnose, cure or prevent disease. Medications compounded by NexGen Pharmaceuticals are prepared at the direction of a veterinarian. NexGen Pharmaceuticals compounded veterinary preparations are not intended for use in food and food-producing animals.
NexGen Pharmaceuticals, LLC does not recommend, endorse or make any representation about the efficacy, appropriateness or suitability of any specific dosing, products, procedures, treatments, services, opinions, veterinary care providers or other information that may be contained in this blog post. NEXGEN PHARMACEUTICALS, LLC IS NOT RESPONSIBLE NOR LIABLE FOR ANY ADVICE, COURSE OF TREATMENT, DIAGNOSIS OR ANY OTHER INFORMATION, SERVICES OR PRODUCTS THAT YOU OBTAIN THROUGH THIS BLOG POST