How can tying-up be confirmed and differentiated from muscle soreness or strain?
Diagnosis of tying-up is confirmed by detection of elevated serum activities of creatine kinase (CK) and aspartate aminotransferase (AST) in the blood. CK and AST are muscle proteins that are released into circulation when muscle cells are damaged. Elevations in CK increase quickly following an episode of tying-up; peak values usually occur four to six hours following the attack. Trends in AST are realized more slowly with levels remaining elevated for seven to 10 days following an episode. Equine athletes often encounter muscle strain. While muscle injuries can cause lameness and require a period of rest, pain is less severe than in tying-up. Most definitively, however, is the fact that CK and AST levels will be only mildly increased, if at all, in horses suffering from soreness or strain.
