MSK Individual Readiness Assurance Test (iRAT) Practice Test

When muscle tissue is injured, enzymes stored in muscle cells leak into the bloodstream. The most useful early signal of skeletal muscle injury in horses is creatine kinase, which is abundant in skeletal muscle and rises quickly after damage. Aspartate aminotransferase is also released from damaged muscle fibers and is commonly elevated in equine muscle injury, so seeing both enzymes elevated supports a muscle-origin problem. Other enzymes aren’t as informative for this scenario: ALT is more liver-focused and less sensitive for muscle injury in horses; amylase and lipase indicate pancreatic or gastrointestinal processes; troponin I points to cardiac injury rather than skeletal muscle damage. So the typical serum pattern in equine muscle injury is elevation of creatine kinase and aspartate aminotransferase.