A horse with raised muscle enzymes is always a cause for concern for riders and trainers, whether it is a single isolated incident or a regular occurrence. The muscle enzymes (aspartate aminotransferase, AST and creatine phosphokinase, CPK) when present at a high level in blood usually indicates muscle damage. This may simply be a result of overexertion during training, but can signify a more serious issue in the form of exertional rhabdomyolysis (ER) or ‘tying up’. These horses, which are quite often fillies or mares, can be notoriously difficult to train and compete with many lost training days resulting in a decreased opportunity to race or compete.
There has been a slow but steady increase in our knowledge of this disease or syndrome, which in more recent years has been helped by the application of genetic based tests for some forms. An increase in our understanding of the metabolic basis for the syndrome is imperative and will help us to better manage these horses in terms of nutrition and training.
