Saturday, March 20, 2010

Capture myopathy




I was unaware that capture myopathy is a big danger when handling wild animals until I saw the condition referenced in this article about the National Zoo losing almost their colony of big-eared bats (drawing, 1st image). Capture myopathy - also known as exertional, transport, stress, or degenerative myopathy; exertional rhabdomyolysis; or white muscle disease - is a non-infectious disease characterized by damage to muscle tissues brought about by extreme exertion, struggle, or stress. It is incurable and caused by a change in metabolism that causes a buildup of lactic acid in the bloodstream that causes muscle to die. It can occur in mammals (particularly ungulates) and birds anywhere that wildlife is trapped or captured, and may be exacerbated by warm weather. Marked by increased breathing and heart rate, uncoordinated movement (a stiff gait or tremors), and red or brown urine, onset of capture myopathy make take weeks or mere minutes. It often results in death, and a necropsy will show swollen kidneys and hemorrhage or edema in the muscles and lungs. Animals with a deficiency of selenium in their diet may be predisposed to capture myopathy. Other factors include species, age, previous experiences, general health, genetics, and learned/innate behavior. To prevent the disease, experts recommend minimizing pursuit and handling time, selecting appropriate weather conditions, and placing animals in a less stressful environment as quickly as possible.

In a court case in Maine about the trapping of lynx, an expert witness testified that capture myopathy is the equivalent of post-traumatic shock in humans. Biologists in Spain warn about susceptibility to the disease when capturing little bustards (3rd image) for radio-tagging, and write that it is seen frequently in long-legged birds, like flamingoes, ostriches, and cranes. Operation Migration, which reintroduces endangered whooping cranes into the wild, recommends hooding the birds when they are handled for banding or physical examination. A survey by a member of the Deer, Elk & Reindeer Farmers' Information Network found that of a total of 5,200 animals, capture myopathy occurred in 6% of fawns, 12.5% of yearlings, and 20.6% of adults. The Irish Hare Initiative warns that capture myopathy has ethical and practical implications for researchers, veterinary professionals, carers, conservationists, and field sports enthusiasts. Western Animal Rescue of Australia urges those who report an injured or displaced wallaby or kangaroo (joey pictured, 2nd image) to simply observe the animal until help arrives, since they don't handle capture very well. And the American Mustang Foundation points out that round-ups of wild horses result in instances of capture myopathy, requiring euthanasia after injuries sustained during capture, dying during transport, or suffering severe stress triggered by the sound of helicopters like those used to capture them. It certainly makes the Chincoteague Pony Swim seem a little less romantic...

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