Sedation in Bactrian Camels
The terms “anesthesia” and “sedation” are often used interchangeably, but there is a distinct difference between the two, as well as their effects. Anesthesia is a pharmacologically-induced, reversible state of amnesia, analgesia, loss of responsiveness, and loss of skeletal muscle reflexes. Sedation is a pharmacologically-induced depression of consciousness during which a patient (animal or human) cannot be easily aroused, but may respond following certain types of stimulation.1
While there are stages of anesthesia which describe the depth of anesthesia as a patient progresses toward the desired stage (surgical plane) of anesthesia, depths of sedation generally describe the varying levels of sedation brought about by sedative drugs. The desired depth of sedation is usually predicated upon the depth necessary for the procedure at hand (e.g., transportation, wound suturing). Light sedation may be used for simple, non- or less-invasive procedures, while heavy sedation is used for some surgical procedures where general anesthesia has been deemed unnecessary or of high risk. There are also some drug classes that are used exclusively as sedatives or anesthetics, and others that may be used for either anesthesia or sedation, depending on dosages and route of administration.
The advantages of sedation over general anesthesia typically focus on patient safety, and to a lesser degree, the circumstances at hand during a given chemical immobilization event. The comparative safety of sedation over general anesthesia in human and animal patients is well-documented. Sedation is associated with decreased risk in many species, thus it is often considered in place of general anesthesia whenever possible.1 The focus on the use of sedation in exotic animals such as Bactrian camels is a result of the perception of greater anesthetic risk in these animals, particularly in those that have undergone the stress of capture.
Other advantages of sedation include general reduction of anxiety and stress, and for more expeditious diagnostic sampling and therapeutics. In some cases, the risk of handling must be weighed against the risk of foregoing diagnostic testing or procedures, or risk of general anesthesia. For these patients, sedation provides an attractive alternative.1
Bactrian Camels: Background and Biology
The Bactrian camel (Camelus bactrianus) inhabits parts of central Asia and western China. The most obvious characteristic that sets Bactrian camels apart from dromedary camels (Camelus dromedarius) is that Bactrian camels have two humps on their backs, whereas dromedary camels have only one.2 Like dromedary camels, Bactrian camels are large animals with an average height of 6-1/2 feet high at the hump. Males weigh 900 to 1,400 pounds; females are about 10% smaller and lighter.
Camels were used almost exclusively as pack animals on the Silk Road, the network of trade routes that was used between Europe and Asia for 1,500 years. This was because they could carry more weight than horses or donkeys, needed less water and were able to thrive on tough desert plants. Arabian camels were used primarily on western Silk Road routes, while Bactrian camels were used in the colder areas of Central Asia, Mongolia and China.3
The coat of the Bactrian camel is usually a dark brown or dirty gray color, although some Bactrian camels are a light tan or white. Bactrian camels also have longer hair than dromedary camels; the coat is thicker and heavier on the head, neck, humps, forelegs, and tail regions. Seasonal temperature changes in their ranges require Bactrian camels to shed their heavy coats when the seasons change.2
Bactrian camels have a double row of long eyelashes that block harsh winds that 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 6-20 individuals, although they occasionally aggregate in groups of 30 or more. Herds typically consist of one alpha adult male leading adult females and their calves. Both camel species are polygynous, wherein the dominant male will mate with any of the females in the herd. The Bactrian camel's breeding season takes place in March and April. Calves are born weighing about 37 kg and are fully mobile within the first 24 hours. Calves in the wild are typically weaned within the first two years.2,4
Chemical Immobilization Risks in Bactrian Camels
The term “chemical immobilization” covers both anesthesia and sedation. There are many physiological and metabolic changes that occur as a result of chemical immobilization, not all of which are caused by the immobilizing agents. Many of these changes are due to the stress of capture.
Given their level of domestication, most camelids (llamas, alpacas and camels) are quite tractable, thus physical restraint, sedation and local anesthetic techniques are frequently used to provide immobility and analgesia. General anesthesia techniques are similar to those for ruminants and horses. 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 associated with anesthesia in camels.7 Observation and monitoring of palpebral and ocular reflexes, eyeball position, and pupil size can be used to monitor the depth of anesthesia. Other risks associated with the capture of camels include hypothermia, hyperthermia, frostbite, bloat, respiratory depression/arrest and cardiac arrest. Usually however, recovery from anesthesia in Bactrian camels is uneventful.7,10
Disadvantages of sedation (versus anesthesia) can include incomplete elimination of patient movement, patient semi-awareness, and lack of complete analgesia. The most obvious risk in these cases is an increased danger to handlers, since camels are very large animals.3
The American College of Veterinary Anesthetists (ACVA) has published recommendations for monitoring animals that are sedated without general anesthesia:
- Palpation of pulse rate, rhythm and quality
- Observation of mucous membrane color and CRT
- Observation of respiratory rate and pattern
- Auscultation
- Pulse oximetry, supplemental oxygen, and endotracheal tube (where applicable) and materials to obtain vascular access should be readily available1
Agents for the Sedation of Bactrian Camels
In general, sedatives produce calmness, loss of aggression and loss of alertness which are usually required during transportation and for minor procedures. In this condition, a camel will not be immobilized fully and can be aroused by various disturbances. Therefore, sedatives are usually used singly for only very minor procedures, or as adjuncts to dissociative anesthetics for hastening smoother induction and to reduce the quantity of anesthetic for achieving more effective immobilization. The combined synergistic effect of tranquilizers and anesthetics is far greater than the individual effect of either of the two drugs relative to attaining smooth induction, good muscle relaxation and smoother recovery.6
It should be noted that endotracheal intubation (general anesthesia) is recommended for any camel undergoing procedures lasting longer than 20 minutes.
The sedatives commonly used in veterinary medicine include drugs such as midazolam, alprazolam, amitriptyline, buspirone, clomipramine, dexmedetomidine, diazepam, fluoxetine, lorazepam, paroxetine, sertraline, or trazodone. Acepromazine is also widely used in veterinary medicine as a sedative.6,8
Midazolam is often used in veterinary medicine for pre-anesthesia and sedation and has a wide margin of safety. When combined with an opioid, its effects are synergistic, allowing a reduction of the amount of either drug.5 Dosages most commonly used are 0.5-10 mg/kg, combined with an opioid. Effects are variable, from a slight decrease in activity to lateral recumbency. These effects are likely related to species variability in response and the varying dose rates suggested for different species/groups. In all cases, patients may still react somewhat to handling and noxious stimuli.5
When midazolam is used alone, sedation may be adequate in ruminants, camelids and several other species. When used in combination with other drugs (e.g., opioids, ketamine, acepromazine, dexmedetomidine), midazolam provides more reliable sedation. In mammals, additional sedation can be provided with sub-anesthetic dosages of ketamine or alfaxalone administered IM. If additional immobilization is essential, low concentrations of inhalant gas can be considered.8
Drugs used for the sedation of Bactrian camels will vary depending upon the preference and experience of the veterinarian or wildlife management personnel. The available literature often suggests that dosing higher when in doubt is in fact safer than dosing conservatively, in that there is more risk to a partially-immobilized animal and to human handlers than there is to a heavily-dosed animal.8,9 This is due to the relative safety of modern drug formulations, which allow for wider latitude in dosing without putting an animal’s health or life at risk.
1Lennox, A., DVM. Sedation as an Alternative to General Anesthesia in Exotic Patients. Delaware Valley Academy Veterinary News, March, 2010.
5Balko, J. et al. Advancements in Evidence-Based Anesthesia of Exotic Animals. Veterinary Clinics: Exotic Animal Practice, Volume 20, Issue 3, 917 – 928.
7Sontakke, S., et. al. A Manual on Chemical Immobilization of Wild Animals. European Journal of Wildlife Research, 36 pp 34-41.
8Arnemo, Jon & Kreeger, Terry. (2018). Handbook of Wildlife Chemical Immobilization 5th Ed.
9Ball, L. Camel Anesthesia. Wiley Online Library, 25 July 2014.
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.