Camel Sedation
“Anesthesia” is a pharmacologically-induced reversible state of amnesia, analgesia, loss of responsiveness, and loss of skeletal muscle reflexes. In contrast, “sedation” is a pharmacologically-induced depression of consciousness during which an animal cannot be easily aroused, but may respond following certain types of stimulation. 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 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
Camel Background and Biology
Camels are ungulates that inhabit the desert areas of western Asia and central and east Asia. Camels encompass two main species: the dromedary camel (Camelus dromedaries, or the Arabian camel) and the Bactrian camel (Camelus bactrianus). The dromedary camel has a single hump and lives in the warmer areas of western Asia and Arabia; the Bactrian camel has two humps and is native to east Asia.
The ancestors of modern camels evolved in North America during the Palaeogene period and later spread to Asia, subsequently becoming extinct in North America.2 Most of the estimated 14 million dromedary camels alive today are domesticated. It is believed that there are about 1,000 wild Bactrian camels in China and Mongolia, with several million more domesticated Bactrian camels in existence in east Asia.
Camels were first domesticated between 3,000 to 3,500 years ago.3 They were widely used as pack animals on the Silk Road, the network of routes used by traders between Europe and Asia for more than 1,500 years. This was chiefly because they were able to 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.
Camels have an upper lip that is split in two with each part being independently mobile. This facilitates their ability to forage in harsh conditions. They also have a three-chambered rather than a four-chambered digestive tract.2,4 Their humps store up to 80 pounds of fat, which camels break down into water and energy when food is scarce.3,4
Fully-grown camels stand about 6 feet at the shoulder and approximately 7 feet at the hump. They can run up to 40 miles per hour at a sprint, and sustain speeds of up to 25 miles per hour.4
Dromedary camels were first introduced into Australia in the 1840's to assist in the exploration of inland Australia, and as a result, there are over one million feral camels in the rangeland ecosystems of Australia today.5 Unfortunately, these animals are causing significant damage to the natural environment. As a control method, radio-collared camels are being used to enhance population control programs. The routinely-performed procedure of radio-collaring—which includes chemical immobilization of the feral animals—carries the risk of numerous potential complications.
Chemical Immobilization Risks in 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 capture of the animal itself.
Given their level of domestication, most camelids (llamas, alpacas and camels) are often quite tractable, thus physical restraint 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 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. These disadvantages can be overcome with careful dosing and monitoring, effective patient handling and efficient use of analgesics when handing and/or when procedures are expected to produce discomfort.3
The American College of Veterinary Anesthetists (ACVA) has published recommendations for monitoring animals that are sedated without general anesthesia (ACVA recommendations):
- 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 Camels
Sedatives produce calmness, loss of aggression and loss of alertness; these are usually required during transportation and for minor procedures. In this condition, a camel is not 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
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 human and veterinary medicine for the purposes of pre-anesthesia and sedation and has a wide margin of safety in many species. When combined with an opioid, its effects are synergistic, allowing a reduction of the amount of either drug.4 Dosages most commonly used are 0.5-10 mg/kg, combined with an opioid (butorphanol, buprenorphine, hydromorphone, other). Effects are variable, from 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 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. It should be noted that use of sedation and manual restraint alone is inappropriate for any procedure expected to produce discomfort. In mammals, additional sedation can be provided with sub-anesthetic dosages of ketamine, 2-7 mg/kg, or alfaxalone, 1 mg/kg IM. If additional immobilization is essential, low concentrations of inhalant gas can be considered.9
Drugs used for the sedation of 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.9,10 This is primarily due to the relative safety of modern drug formulations, which allow for much more 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.
6Balko, J. et al. Advancements in Evidence-Based Anesthesia of Exotic Animals. Veterinary Clinics: Exotic Animal Practice, Volume 20, Issue 3, 917 – 928.
8Sontakke, S., et. al. A Manual on Chemical Immobilization of Wild Animals. European Journal of Wildlife Research, 36 pp 34-41.
9Arnemo, Jon & Kreeger, Terry. (2018). Handbook of Wildlife Chemical Immobilization 5th Ed.
10Ball, 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.
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