Chemical Immobilization of Bactrian Camels
The term “immobilization” refers to any forced restriction of movement of all or part of an animal’s body, while “chemical immobilization” achieves this using drugs which have a range of intended effects. These may include unconsciousness with lack of sensation (anesthesia), or widespread muscular paralysis while the animal is fully or partially conscious (sedation).1 Wildlife managers, veterinarians and researchers sometimes need to immobilize camels to mark them for identification, provide veterinary treatment or to perform management functions.
Camels inhabit the desert areas of western Asia and central and east Asia, and are comprised of two main species: the dromedary camel (Camelus dromedaries, or the Arabian camel) and the Bactrian camel (Camelus bactrianus). The Bactrian camel has two humps and is native to east Asia, while the dromedary camel has a single hump and lives in western Asia and the Middle East.
Camels were first domesticated 3,000 years ago, and today, approximately 90% of the world’s camels have been domesticated.2 This reduces much of the potential capture stress that they might suffer compared to other wild animals, yet chemical immobilization still carries some risks for complications in these animals.
Bactrian Camel Basics
The ancestors of modern camels evolved in North America during the Palaeogene period and later spread to Asia, later becoming extinct in North America.4 While most camels alive today have been domesticated, there are approximately 1,000 wild Bactrian camels in China and Mongolia, with several million more domesticated Bactrian camels in east Asia.
Camels were used extensively as pack animals on the Silk Road (the network of trade routes used between Europe and Asia for more than 1,500 years) because they could carry more weight than horses or donkeys, needed less water and were able to thrive on tough desert plants. Today, camels are still used for milk, meat and as pack animals.
Both Bactrian camels and dromedary camels are large animals with an average height of 7 feet. Bactrian camels are noted for their shaggy coats, which they shed during the summer months. They have a double row of long eyelashes that block the harsh winds which can blow sand and dust into the camels' eyes. Their ears are also lined with hair and their top lip is divided to aid in foraging in harsh conditions. Their nostrils can be closed to shield against dust and sand.
Wild Bactrian camels live in herds of about 6 to 20, although they sometimes gather in much larger groups. Herds typically consist of one adult male leading adult females and their calves. Bactrian camels are not territorial; occasionally, multiple herds will cross paths and form a larger herd which can reach up to 500 individuals. Herds spend the majority of their days migrating and grazing. During the winter months, Bactrian camels migrate to the Gobi desert steppe, returning to the desert when the snow melts in the spring.2
Sedation and Anesthesia of Bactrian Camels
Most camels are large enough to be considered difficult to handle in the event that they become frightened or agitated. Chemical agents (sedatives and/or anesthetics) may be delivered by hand to a restrained camel by using a pole syringe, or by using a capture gun (either a handgun or along gun). Capture guns are fired by CO2 gas cartridges or with .22 caliber blanks. Syringes (often called darts) are loaded through a breech, one shot at a time. The effective range may be up to 60 yards.7 Remote chemical immobilization is carried out by approaching camel and shooting a dart from a helicopter, snowmobile, an off-road vehicle, or from the ground.
The chemical immobilization of Bactrian camels carries inherent risks. These include, but are not limited to capture myopathy, hypothermia, hyperthermia, respiratory depression/arrest, aspiration and cardiac arrest. Additionally, if the onset (induction) of anesthesia is slow, the risk of physical injury such as lacerations, limb injuries, head trauma etc. is increased. It is extremely important for personnel in the field and support staff to be familiar with animal handling and immobilization techniques, as well as potential emergencies.
Depending on the procedure(s) being performed, a camel may be handled using heavy sedation or general anesthesia (for invasive surgical procedures). Drug choices and combinations must be of proven safety and calculated for the camel’s weight, age, physiological and reproductive status and body condition.8,9
Most camelids (llamas, alpacas and camels) are agreeable when it comes to handling due to their level of domestication. Thus, physical restraint and local anesthetic techniques are often used to provide immobility and analgesia. General anesthesia techniques are similar to those for ruminants and horses, and endotracheal intubation is recommended for any camel undergoing procedures lasting longer than 20 minutes. Regurgitation of compartment one (C1) of the stomach contents (which can occur in many chemically-immobilized ruminants), postoperative nasal congestion and associated respiratory distress postextubation are potential hazards specifically associated with anesthesia in camels.6
Immobilizing Agents for Bactrian Camels
The possession and use of drugs used to immobilize Bactrian camels and other hoofstock is governed by federal and state regulations in the United States. All drugs currently used to sedate or immobilize wild animals are prescription drugs and must be used by or on the order of a licensed veterinarian. This requires that a veterinarian must be involved in the process, but it does not necessarily mandate that a veterinarian is physically present during the immobilization process. Some drugs used chemical immobilization are also classified as controlled substances, the possession of which requires a U.S. Drug Enforcement Agency (DEA) registration number, special record keeping and special storage. Non-veterinarians using prescription drugs under a veterinarian’s supervision should receive adequate training in their use.
The classes of immobilizing agents used on Bactrian camels include:
Paralytic Drugs: The neuromuscular blocking (NMB) or paralytic drugs are some of the earliest drugs used for the chemical immobilization of wildlife, and are being used less frequently today than in years past. There are two major deficiencies relative to the use of NMB drugs. One is that NMB drugs have a very low safety margin: dosage errors of only 10% can result in either no effect (underdosing) or death by asphyxia (overdosing). Mortality rates as high as 70% have occurred.9
The second deficiency is that NMB drugs are virtually devoid of central nervous system effects because of their inability to cross the blood-brain barrier. Thus, a camel paralyzed with NMB drugs is conscious, aware of its surroundings, fully sensory, and, as such, can feel pain and experience psychogenic stress yet is physically unable to react.9,10 Because of these deficiencies, NMB drugs should be used with extreme care.
Tranquilizers/Sedatives: The primary use of tranquilizers in wildlife immobilization is as adjuncts to anesthetics (e.g., ketamine, carfentanil) to hasten and smooth induction and recovery and to reduce the amount of the primary agent required to achieve immobilization. Valium is used for some animals as an anticonvulsant adjunct to ketamine anesthesia and it is also an excellent muscle relaxant.
The α-adrenergic tranquilizers (e.g., xylazine or Rompun, medetomidine) are potent sedatives that can also be completely reversed.8 These are often combined with ketamine, Telazol, or carfentanil. By themselves, they are capable of heavily sedating animals, particularly ungulates, to the point of relatively safe handling. However, animals sedated with these tranquilizers generally can be aroused with stimulation and are capable of directed attack.
Dissociative Anesthetics: This group of drugs (ketamine, tiletamine) is characterized by producing a cataleptic state in which the eyes remain open with intact corneal and light reflexes. Ketamine is probably one of the most widely used drugs for wildlife immobilization because of its efficacy and safety. Tiletamine is unavailable as a single product and it is combined in equal proportions with the diazepinone tranquilizer, zolazepam (e.g., Telazol).When used singly, ketamine usually cause rough inductions and recoveries, and convulsions are not uncommon.10 Because of this, they are usually administered concurrently with tranquilizers or sedatives. There is no complete antagonist for ketamine or Telazol.
Opioid Anesthetics: The opioids have been used for the chemical immobilization of wildlife since the 1960s and are the most potent drugs available for this purpose. The most commonly used opioid for wildlife immobilization is carfentanil. A major advantage in the use of opioids is the availability of specific antagonists. The potency of opioids, such as etorphine and carfentanil, is both an advantage and disadvantage. The advantage is the reduced volume of drug required for immobilization makes them the only class of drugs capable of remote immobilization of large animals. The disadvantage is that they are potentially toxic to humans even with low exposure. Death is almost always due to respiratory failure. Opioids should never be used while working alone or without having an antagonist on hand.9
Reversal Agents
The duration of anesthesia in Bactrian camels will be influenced by the drugs used, age, sex, body weight, procedure performed and the amount of stimulus during the procedure. Whether sedation or general anesthesia has been used, reversal agents may be required to neutralize sedatives or anesthetics, thus allowing the camel to completely recover from being anesthetized.
In recent years, chemical immobilization protocols and drug development have been refined in order to keep these within safety margins through the use of novel anesthetics, including combinations of true anesthetics, neuromuscular blockers and tranquilizers.10 The use of antagonists (reversal agents) to anesthetics is now widely employed, as this avoids the undesirable effects of immobilizing drugs and facilitates speedy recovery from chemical immobilization events.8,9
Veterinary custom compounding pharmacies have widely expanded the variety, availability and efficacy of immobilizing drugs through the development of custom formulations for wildlife such as Bactrian camels. Some of these are available in kit form, which include both the immobilizing and reversal agents.
5Balko, J. et al. Advancements in Evidence-Based Anesthesia of Exotic Animals. Veterinary Clinics: Exotic Animal Practice, Volume 20, Issue 3, 917 – 928.
7Ball, L. Camel Anesthesia. Wiley Online Library, 25 July 2014.
8Arnemo, Jon & Kreeger, Terry. (2018). Handbook of Wildlife Chemical Immobilization 5th Ed.
9Nielsen, L. Chemical Immobilization of Wild and Exotic Animals. (1999) Ames, Iowa, Iowa State University Press.
10Stoskopf, M. Handbook of Wildlife Chemical Immobilization. Journal of Wildlife Diseases 2014 50:1, 157-157.
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.
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