Capture myopathy is a non-infectious condition that primarily impacts wild animals during or after capture and handling. It is a stress-induced disease that can lead to severe illness and death. This condition challenges animal welfare and conservation efforts, as it can compromise the health and survival of individual animals and populations. Understanding this syndrome is important for anyone involved in wildlife management or interested in animal well-being.
Understanding Capture Myopathy
Capture myopathy results from extreme physiological stress, often linked to exertion or struggle. It involves muscle damage, known as rhabdomyolysis, which occurs when an animal’s body undergoes an exaggerated ‘fight or flight’ response.
During intense exertion, muscles demand more oxygen than the blood can supply, leading to anaerobic metabolism where energy is produced without sufficient oxygen. This process results in a buildup of lactic acid, which enters the bloodstream and can lower the body’s pH, a state known as metabolic acidosis. The accumulation of lactic acid and other metabolic byproducts damages muscle cells, causing them to release myoglobin into the bloodstream. This myoglobin can then damage the kidneys, potentially leading to kidney failure and systemic complications.
What Causes Capture Myopathy
Capture myopathy is triggered by various stressors that overwhelm an animal’s physiological systems. Physical exertion during pursuit, such as a prolonged chase or struggle in a trap, can lead to muscle exhaustion. The duration of pursuit and the method of capture influence the condition’s occurrence.
Psychological stress from fear, unfamiliar surroundings, or the presence of humans also contributes to the exaggerated stress response. Common capture methods like netting, darting, or trapping can induce this stress. Hotter temperatures and repeated chemical immobilization can further increase an animal’s susceptibility to capture myopathy.
Recognizing the Signs
Signs of capture myopathy can manifest immediately or hours to days after a stressful event. Acute signs, appearing soon after capture, include an elevated respiratory rate, increased heart rate, and a rise in body temperature, sometimes exceeding 42°C (107.6°F). Animals may also exhibit muscle tremors, stiffness, weakness, uncoordinated movements, or collapse.
Delayed signs can emerge hours, days, or even up to two months following capture. These include lameness, paralysis, a reluctance to move, depression, or sudden death. The kidneys may appear swollen and dark, and urine may be dark red due to myoglobin. Affected muscles in the limbs, neck, or back may appear pale and dry.
Impact on Wildlife and Conservation
Capture myopathy threatens wildlife populations and conservation initiatives. It is a primary cause of death in wild animals undergoing human handling, leading to high mortality rates during and after capture and translocation efforts. This is particularly concerning for endangered or sensitive species, where individual losses significantly impact overall population viability.
The condition complicates essential conservation activities like research, translocation programs, and veterinary care. It can undermine the success of reintroduction or population supplementation efforts, making it harder to achieve conservation goals. Beyond the direct loss of animals, there are also ethical implications for animal welfare, as the condition reflects severe stress and suffering.
Preventing Capture Myopathy
Preventing capture myopathy involves careful planning and best practices to minimize stress on wild animals. Reducing chase time during capture is important, and appropriate capture methods should be selected for the species and situation. Using chemical immobilization techniques, such as darting with sedatives or anesthetics, can help reduce physical exertion and fear, though these drugs do not prevent increases in body temperature.
Rapid processing and minimizing handling time are also recommended. Reducing sensory stimulation, such as keeping animals in dark, quiet environments, can help lower stress levels. Proper handling during transport, including maintaining a calm environment and appropriate temperatures, is also important. Post-release monitoring can help assess the success of the intervention. The use of experienced personnel and proper equipment is important throughout capture and handling to reduce risk.