Capture Myopathy in Kudu Antelope During Capture and Chemical Immobilization

Capture myopathy (also called exertional capture myopathy or exertional rhabdomyolysis) is a non-infectious but life-threatening syndrome of wild or domestic animals in which muscle damage results from extreme exertion. It often occurs as a result of capture, transport or chemical immobilization events, but it can also be brought about by natural stressors.

Capture myopathy can occur in any animal under extreme stress, although some species are more susceptible than others due to their behavioral and physiological characteristics. Capture myopathy has been best studied and most frequently seen in hooved mammals and birds. “Some North American ungulates reported with this disease include white-tailed deer, mountain goats, bighorn sheep, pronghorn antelope, bison, moose, and elk. Birds reported with CM include flamingoes, sandhill cranes, snow geese, Canada geese, mallards, wild turkeys, gulls, bald eagles, and golden eagles. Capture myopathy may even occur in fish and amphibians.”¹ Capture myopathy can occur when prey animals are attempting to avoid predators, but it is usually more often caused due to protracted struggle in man-made restraints.

Clinical signs of capture myopathy can vary depending on the species and the cause of exertion. Early signs usually include elevated respiratory rate and heart rates and elevated body temperature. Although it can result in sudden death, clinical signs can also develop hours, days, or up to two months following capture.^1,2 Late clinical signs can include depression, lack of responsiveness, loss of coordination, muscle stiffness, tremors, muscle paralysis, shock and death. Treatment of wildlife suffering from capture myopathy is rarely successful, and animals typically die from this condition.

During a capture event, dark red-colored urine is an indication that the animal's muscles are breaking down and that its kidneys have been severely affected.^3-5 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.⁴ Light-colored skeletal and cardiac muscle seen upon necropsy is indicative of capture myopathy being the cause of death.

Chemical Immobilization and Capture Myopathy in Kudu

The kudu is a large African antelope that consists of two subspecies: the greater kudu (Tragelaphus strepsiceros), and the lesser kudu (Tragelaphus imberbis). The greater kudu is second in size to the eland, Africa’s largest antelope. The greater kudu inhabits the dense brush and forested areas of southern Africa, while the more elusive lesser kudu is common in the arid lowland thornbush of northeast and East Africa.⁵ For food, both kudus forage on a wide variety of trees, shrubs, vines, herbs, seedpods, fruits and grasses. Both species prefer the green growth along watercourses in dry seasons and disperse through deciduous woodlands during rainy seasons.⁶

The veterinary care of kudu has become commonplace due to the integration of veterinary medicine in wildlife management programs, zoological collections, exotic animal ranching expansions and the private collection of wildlife species.⁵ As a result, wildlife managers and veterinarians are frequently called upon to anesthetize and handle these animals.

Since both species of kudu are forest-dwellers and elusive, difficulties in capturing them can increase the risks for capture myopathy. Like other antelope, kudu are adapted to escape from predators, but they are not adapted to struggle for long periods of time in human-constructed restraints.³ When animals overexert themselves (e.g., struggling in a trap) to the extent that physiological imbalances develop and result in severe muscle damage, capture myopathy results.² High environmental temperatures and repeated chemical immobilization can increase the risk of kudu suffering from capture myopathy.⁴

Source/Credit: Oxford University Press

Preventing Capture Myopathy in Kudu

Since there is no treatment for capture myopathy, prevention is the best method of avoiding this condition in captured kudu. An anesthetic protocol consisting of properly-formulated anesthetic agents can aid significantly in preventing capture myopathy. The remote delivery of anesthetic agents is a superior methodology to trapping these animals prior to any procedures being performed.

Appropriate anesthetic protocols may vary depending on conditions, so adequate preparation is essential in determining 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 by no means a guarantee of avoiding capture myopathy in any antelope.³ Kudu 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.⁵ Capture methods that minimize animal stress, struggling and handling time should always be utilized.