Cardiac troponins in diagnostics of equine myocardial injury

Unlike humans, who no longer need to run or walk for surviving, riding is the natural horses’ occupation, which justifies their use in many working and recreational activities. Despite a difference in size, the biochemical, biological, anatomic, physiological, physiopathological and pathological characteristics of the heart are almost unvaried in humans and horses. Several lines of evidence now attest that the measurement of cardiac troponin I (cTnI) or T (cTnT) has become the cornerstone for diagnosing cardiac injuries in humans, independently from the ischemic, infective, traumatic, toxic, inflammatory or autoimmune origin, thus paving the way to extend their clinical use in equine cardiology. Post-exercise increments of both cTnI and cTnT are commonplace in active horses and need to be accurately distinguished from pathological increases as in humans. Taken together, current literature data would hence lead us to conclude that the clinical significance of measuring cTnI or cTnT in humans and horses appears nearly overlapping, though some important drawbacks must be recognized. These include preliminary analytical and clinical validation of human methods in horses before introduction into veterinary practice, accurate definition of reference ranges and diagnostic thresholds, which could be method-, bread-, age-dependent, as well as validation of human diagnostic algorithms in horses and appropriate interpretation of post-exercise variations, which are more frequent in equines than in humans. A final consideration shall be made on the use of algorithms for diagnosing myocardial injury. Although these have been largely validated in humans, and equine and human cardiology displays many overlapping features, clinical validation would always be needed before straightforwardly translating human algorithms into equine diagnostics.