Capture Myopathy in Camels During Capture and Chemical Immobilization
Camels are even-toed ungulates that inhabit the desert areas of western Asia and central and east Asia. There are two main species of camel: 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.
According to fossil evidence, the ancestors of modern camels evolved in North America during the Palaeogene period and later spread to Asia, subsequently becoming extinct in North America.1 Most of the estimated 14 million dromedary camels alive today are domesticated animals. 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.2 They were used almost exclusively 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 largely because they could carry more weight than horses or donkeys, needed less water and were able to thrive on tough desert plants. 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 less-than-ideal conditions. They also have a three-chambered rather than a four-chambered digestive tract.1,3Their humps store up to 80 pounds of fat, which camels break down into water and energy when food is scarce.2,3
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.3
Capture Myopathy in Camels
Capture myopathy (CM) is a serious condition that can occur in both wild and domestic animals wherein muscle damage results from extreme exertion, struggle, or stress. This condition is also known as exertional myopathy, overstraining disease and exertional rhabdomyolysis.4 Capture myopathy most often occurs as a result of capture, transport or chemical immobilization, but it can also be the result of other natural causes of stress, such as in prey animals attempting to avoid or struggling with predator animals.5 Capture myopathy is of particular ethical concern in cases when it is a cause of death in animals that are handled by humans, such as in chemical immobilization events.
Capture myopathy can occur in any animal under extreme stress, although it is thought that some species may be more predisposed to it than others due to their temperament and physiological characteristics.6 Capture myopathy has been most widely studied in ungulates and birds, although it is believed to potentially affect any captured wildlife species. It has also been observed in coyotes, badgers, primates, and many other species.5
Causes and Clinical Signs of Capture Myopathy
Capture myopathy can occur naturally when an animal is attempting to avoid predation, but since modern camels have few predators and are largely domesticated, for the purposes of this discussion, it will be the result of these animals being captured and/or immobilized. Like other animals, camels are not adapted to struggle for long periods of time in human-constructed restraints.6 When animals overexert themselves (e.g., attempting to flee a capture team) to the extent that physiological imbalances develop and result in severe muscle damage, capture myopathy results.5 Increased ambient temperatures and repeated chemical immobilization can increase the risk of animals suffering from capture myopathy.7
Dromedary camels were first introduced into Australia in the 1840's to assist in the exploration of inland Australia. Today, there are over one million feral camels in the rangeland ecosystems of Australia.8 Unfortunately, these animals are causing significant damage to the natural environment as well as having a negative social, cultural and economic impact across their extensive range.
As a control method, radio-collared camels are being used to enhance population control programs. This involves immobilizing individual camels, attaching a telemetry collar, and releasing the collared animal to re-join its herd. The collared individuals are subsequently tracked via GPS and communications satellites.8 This routinely-performed procedure carries the risk of inducing capture myopathy in these animals.
Clinical signs of capture myopathy in camels can vary depending on the cause of exertion.5 The method of capture and restraint is also a determinant in occurrences of CM. The available literature states that capture myopathy may result in sudden death, or that clinical signs may develop hours, days, or up to two months following capture.4 The clinical signs during early onset include elevated respiratory rate, heart rate, and body temperature.4,6 Body temperature increases during exertion, with higher temperatures being associated with death due to CM. The increase in body temperature can be above 42°C.4 Muscle spasms, stiffness and lameness are also clear signs of CM. Animals often become recumbent and may stumble. If dark red-colored urine is noted, this is an indication that the animal's muscles are breaking down and that its kidneys have been severely affected.5-7 Death of the animal usually follows. If the animal survives the acute stage of the condition, scarring of heart and skeletal muscle tissue may permanently debilitate the animal.7 Upon necropsy, light-colored skeletal and cardiac muscle is indicative of capture myopathy being the cause of death.
Preventing Capture Myopathy in Camels
Since there is no treatment for capture myopathy, prevention is the best method of avoiding this condition. Care should be taken in case of handling of animals that tend to be more susceptible to capture myopathy. An anesthetic protocol consisting of good anesthetic agents can aid significantly in preventing capture myopathy in camels. In such cases, the remote delivery of anesthetic agents is a superior methodology to trapping an animal prior to the anesthetic event.
The team in the field should be thoroughly aware of the risks of capture myopathy and make every effort to prevent its occurrence. Camels, or any wild species, should only be captured when necessary, and the negative effects that capture may have on an animal's health should always be considered before beginning a capture or initiating an anesthetic event.8-10 Capture methods that minimize animal stress, struggling and handling time should be utilized. Appropriate methods may vary depending on the subspecies, so research can be helpful in identifying the ideal capture method. It has been reported that using a combination of Xylazine HCL and Ketamine HCL can decrease the chance of capture myopathy, but this is not a guarantee of avoiding this condition in camels.6
4Friend, M., Thomas, N. J. Field Manual of Wildlife Diseases. In: Field Manual of Wildlife Diseases, United States Geological Survey, 361-368.
5Williams, E. S., Thorne, E. T. 1996. Exertional Myopathy (Capture Myopathy). Noninfectious Diseases of Wildlife, Second Edition, 181-193 Iowa State University Press, Ames, Iowa, USA.
6Blumstein, D., et. al. The evolution of capture myopathy in hooved mammals: a model for human stress cardiomyopathy?Evolution, medicine, and public health vol. 2015,1 195-203. 21 Jul. 2015,
7Kohn, Tertius. (2013). Capture myopathy mystery.
9Businga NK, Langenberg J, Carlson L. Successful treatment of capture myopathy in three wild greater sandhill cranes (Grus canadensis tabida). J Avian Med Surg. 2007 Dec;21(4):294-8. doi: 10.1647/2005-013R1.1. PMID: 18351009.
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