Exertional rhabdomyolysis
is common in racing greyhounds, sled dogs and horses.
Rhabdomyolysis is a condition in which damaged skeletal muscles begin to break down. This breakdown releases compounds such as creatine phosphokinase into the bloodstream. In severe cases, rhabdomyolysis can damage the kidneys or even cause death. The form of rhabdomyolysis commonly found in racing greyhounds is exertional rhabdomyolysis, also known as focal rhabdomyolysis, according to the "Introduction to Veterinary Pathology." In this form of the disease, muscle damage results from overuse.
Overexertion
The muscle damage in exertional rhabdomyolysis is focal necrosis of overworked muscles fibers. The necrosis occurs when the blood supply to the muscle fibers is not adequate to keep up with demand. This can occur when a greyhound is raced at a level above its physical capability. If disease or injury interrupts your dog's regular training schedule, give the animal time to build back up to peak performance before racing.
Electrolyte Imbalance
Under normal conditions, hard-working muscles trigger a boost in blood supply by giving out potassium ions. The potassium dilates nearby blood vessels to increase blood flow. If the greyhound is low in potassium or related electrolytes, the dilation effect might be too weak. This can happen if the dog has a pre-existing electrolyte imbalance or if electrolyte depletion occurs during extreme physical exertion. One cause of low potassium in a greyhound is racing too frequently, according to "Nutrient Requirements of Dogs and Cats."
Stress
According to "Welfare of Dogs," rhabdomyolysis is more common among greyhounds that experience stressful conditions. This can include both emotional stresses such as pre-race excitement, overwork or fighting as well as environmental stresses like overcrowding. Keeping or racing a dog in hot or humid conditions is another environmental stress and one that can also contribute to rhabdomyolysis through deyhdration and electrolyte loss.
Tags: blood supply, exertional rhabdomyolysis, muscle damage, racing greyhounds