Exertional Myopathy

Exertional or Capture Myopathy

Risk Factor

Exertional or capture myopathy (disease of the muscle) is a non-infectious disease of muscles that is characterized by damage to muscle tissues brought about by physiological changes, usually following extreme exertion, struggle and/or stress.

Distribution

Geographic:

The potential for this condition can occur anywhere animals are pursued or trapped.

Seasonality:

Species Affected

Both mammals and birds of all ages and sexes are susceptible to this disease.
Species differ in their susceptibility to this disease because of physical and behavioural attributes. It is most commonly seen in wild ungulates in British Columbia.

Mechanism of Action / Signs and Symptoms

Signs vary depending on species, cause of exertion and the biochemical imbalances that cause muscular damage. It may be seen peracutely (immediately), acutely (within minutes) or chronically (in hours, days or weeks).
Early signs include sudden death or increased breathing and heart rates, and increased in body temperature.
Additional signs include: depression, muscle stiffness, weakness, tremors, incoordination, or shock, which may appear within hours to days following severe exertion. If the animal survives, residual signs may last as long as a month.
Urine of affected animals may be red to brown because of broken down components of muscle moving through the kidneys.
Animals that do not initially die may be predisposed to kidney failure, predation and accident.
Muscles may appear pale and wet or very dark red and dry, with variable amounts of hemorrhage and edema present.
Kidneys may appear swollen, and multiple hemorrhages and edema may be present in the lungs.
In severe cases, animals will often die.

Meat Edible?

Meat from an animal with exertional myopathy is suitable for human consumption, although muscle damage may change the taste and will decrease the spoilage time of the meat.

Prevention of Disease

This condition may occur through normal life-history events, particularly when prey species try to escape predators. However, it is more commonly associated with strenuous use of fore and hindlimb muscles when wild ungulates are captured and handled.
This condition is extremely difficult to treat and is best to avoid through prevention.
Prevention relies on methods that reduce stress and damage to animals, minimizing pursuit, struggling and handling time, selecting appropriate weather conditions to handle animals, ensuring proper methods of capture and handling and ensuring animals are released or placed in less stressful conditions as quickly as possible.

Samples for Diagnosis

Portions of affected muscles from different areas of the body as well as sections of heart and kidney tissue should stored in formalin and submitted microscopic examination.

Similar Diseases

The development of exertional or capture myopathy may be predisposed to by nutritional imbalances such as selenium deficiency.