Chemical Immobilization and Sedation in Bactrian Camels
Although the majority of Bactrian camels (Camelus bactrianus) in the world have been largely domesticated, research, zoos and management programs occasionally require the capture and manipulation of these animals. The development of decreasingly invasive procedures over the years have allowed researchers, veterinarians and management personnel to obtain certain types of data without the need to handle animals. Some information, however, can only be obtained via capture.1
Global positioning system (GPS) collars, heat sensitive transmitters and advanced physiological monitoring equipment now allow detailed research on species such as Bactrian camels, but still require the initial capture and manipulation of individual animals.2
The Bactrian Camel: Biology and Habitat
The Bactrian camel is native to central Asia and parts of China. These camels can reach seven feet in height and weigh up to 1,500 pounds.3 Camels are one of the most well-recognized species, but what distinguishes the Bactrian camel from its western cousin the dromedary camel (Camelus dromedarius) is that the Bactrian camel has two humps on its back, while the dromedary (or Arabian) camel has only one hump.
Contrary to popular belief, the humps on a camel’s back don’t store water—they actually store fat, which the camel uses as an energy source when food is scarce. Bactrian camels are grazing animals that subsist on grasses, leaves, and shrubs, but they can also process thorns, salty plants and dry vegetation that are indigestible to other herbivores. This adaptation enables the Bactrian camel to survive in areas of sparse vegetation. They can go for extended periods of time without drinking water, but when they do drink, they can consume up to 30 gallons in one sitting.3
The camel’s adaptations to life in the desert are well-known. The Bactrian camel’s long eyelashes and elongated nostrils (which they can close) protect them from blowing dust and sand. Their split, partially prehensile upper lips allow them to forage vegetation that would be inaccessible to other large herbivores. They have specialized blood cells which allow them to survive periods of dehydration,4,5 and their thick coats change with the seasons; these coats are shed during the summer months.
Wild Bactrian camels, which still exist in their native range, typically form herds of from 6 to 30 individuals led by a single breeding male. Males that do not find mates gather in single-sex bachelor herds. Pregnancy in camels lasts for 11 months, with calves being born in March and April. Juvenile camels mature after about five years, with individuals living up to 50 years.
Drugs Used for Chemical Immobilization
The effects of immobilization on Bactrian camels can differ according to the capture methodology employed. The relevant research agrees that captures by remote delivery of immobilizing drugs via darting lower a camel’s stress levels, thus decreasing the subsequent capture effects as compared to other techniques.6 This is a chief reason why chemical immobilization has become the preferred method of capture, particularly with large mammals such as camels.
The three classes of immobilization drugs that are used on Bactrian camels include opioids, cyclohexamines and neuroleptics.
Opioids
- The most potent drugs available for immobilization
- Specific antagonists are available
- Reduced volume of drugs are typically required
- The only class of drugs practical for remote immobilization of large animals
Cyclohexamines
- Also known as dissociative agents
- Produce altered consciousness
- Dissociate mental state from environmental stimulation
- Retain many vital reflexes
- The animal cannot walk but can move tongue, blink, swallow
- The animal may feel some pain
- Common cyclohexamines include ketamine, tiletamine
- Should not be used alone and are not reversible
- Should be used in conjunction with other drugs, such as neuroleptics
Neuroleptics
- Also referred to as tranquilizers
- Produce calmness and relaxation
- Do not cause loss of consciousness or alleviate pain perception
- Can cause death before they cause loss of consciousness
- Best used in conjunction with other drugs (e.g., cyclohexamines)
- Common neuroleptics include zolazepam, diazepam, xylazine
- Common reversal agents include yohimbine, tolazoline
Chemical Immobilization Techniques
Since Bactrian camels have been so widely domesticated, most are less prone to capture stress than other hoofstock species. In some cases, intramuscular hand injection can be used when working with camels that are cooperative, or those that have been cornered in enclosures. When hand injecting, rapid delivery while minimizing risk to the handler or animal is essential. Pole syringes are also widely used for this purpose; these afford greater distance than approaching an animal for a hand injection without resorting to remote delivery systems. Drug delivery by pole syringe requires manual injection follow through to administer the drug, as the handle is usually an extension of the plunger. As with hand injection, larger bore needles should be used to ensure complete drug delivery.
Remote chemical immobilization is usually carried out by approaching camels and shooting a dart from a helicopter, an off-road vehicle or from the ground. While this can significantly reduce stress compared to physical capture methods, it still impacts the camel’s stress levels. A frightened camel will have an increased heart rate, higher levels of cortisol and other stress-related biochemicals.6 An approach from the ground tends to produce even lower stress levels in camels, because animals are generally less frightened than if a noisy vehicle is used.
Analgesia will be necessary if the camel’s skin has been breached by anything larger than a hypodermic needle, including biopsy instruments. Invasive surgeries should be conducted using general anesthetics with the animal at a surgical plane; intraoperative analgesia that continues after anesthetic recovery should be provided in some form to every surgical patient.1
Intubation is recommended for camels that need to be anesthetized for longer than 20 minutes.9 For analgesic drugs (usually opioids), doses and frequencies of administration may be more difficult to gauge, even with close clinical observation for discomfort.7 These observations can be even more difficult to make in the field than in a clinic or zoo setting, compounding the difficulty in such assessments.
Most of the opioid analgesics (Buprenorphine, Fentanyl, Butorphenol, Oxymorphone, etc.) are effective 12 hours after administration. Longer‐lasting, non‐steroidal anti‐inflammatory analgesics (NSAIDs) such as Meloxicam, Carprofen, Flunixin, Ketoprofen,etc. have longer durations of action than opioids, and can be administered in conjunction with opioids to increase potency of effect and duration of action.7
Reversal Agents
Reversal agents are often required to neutralize sedation or anesthetic agents, thus allowing a camel to completely recover from being anesthetized. This is even more important in the field than in a clinic or zoo setting, because a chemically-compromised animal may be in danger of injury and other hazards.
Duration of anesthesia in the Bactrian camel will be influenced by the drugs used, age, sex, body weight, procedure(s) performed and the amount of stimulus during the procedure(s). Due to the variety of factors that influence duration of anesthesia, the literature maintains that anesthetic drugs should always be titrated to effect. If anesthesia is being maintained by a gas anesthetic (e.g., isoflurane), titration of anesthetic depth can be controlled almost immediately by adjusting the amount of anesthetic gas being administered to the animal. In addition, anesthetic duration can be extended for as long as the anesthetic gas is administered.7
Injectable anesthetics and sedatives do not have the same flexibility as inhalant anesthesia in that once a dose has been administered, it cannot be “un-administered” to facilitate the end of anesthesia coinciding with the end of a procedure.8 In such cases, reversal drugs are used to bring about the desired effect.
Atipamezole is a synthetic α2-adrenergic antagonist that was developed to reverse the actions of compounds such as medetomidine and dexmedetomidine. Atipamezole safely and reliably reverses the effects of these compounds and is widely used in small and large animal practices, as well as in wildlife applications.9
Naltrexone hydrochloride is an opioid receptor antagonist that is used in veterinary medicine to block receptors as a reversal agent for opiate agonists such as butorphanol.
Concerns in the area of conservation and humane treatment have led to great care being taken with chemical immobilization protocols and drug development to keep these within safety margins through the use of novel anesthetics, including combinations of true anesthetics, neuromuscular blockers and tranquilizers.2 Thus, modern chemical immobilization techniques have dramatically reduced the side-effects of drugs and mortalities. Additionally, the use of antagonists to anesthetics is now widely employed, as this avoids the undesirable and potentially harmful effects of drugs and facilitates the speed of animals’ recovery from chemical immobilization.1,2
The drug formulations available for immobilizing Bactrian camels have been refined to a degree that eliminates much of the risk that existed years ago. With the right drug formulations, proper planning and safety precautions in place, experienced personnel can have the expectation of effective and incident-free chemical immobilization of Bactrian camels.
1Brivio F, Grignolio S, Sica N, Cerise S, Bassano B (2015) Assessing the Impact of Capture on Wild Animals: The Case Study of Chemical Immobilisation on Alpine Ibex. PLoS ONE 10(6): e0130957.
2Powell RA, Proulx G (2003) Trapping and marking terrestrial mammals for research: integrating ethics, performance criteria, techniques, and common sense. ILAR J 44: 259–276.
6Arnemo, Jon & Kreeger, Terry. (2018). Handbook of Wildlife Chemical Immobilization 5th Ed.
7Nielsen, L. Chemical Immobilization of Wild and Exotic Animals. (1999) Ames, Iowa, Iowa State University Press.
8Lance, W. Exotic Hoof Stock Anesthesia and Analgesia: Best Practices. In: Proceedings, NAVC Conference 2008, pp. 1914-15.
9Ball, L. Camel Anesthesia. Wiley Online Library, 25 July 2014.
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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.
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