Biomarkers of Intestinal Injury in Colic

SIMPLE SUMMARY: Biomarkers are measurable substances within body tissues or fluids that allow for the identification of ongoing injury or disease. Colic secondary to gastrointestinal disease is one of the most frequent causes of morbidity and mortality in horses. Specifically, colic associated with intestinal ischemia is the most life-threatening variety of this disease. Optimization of biomarkers for the diagnosis of colic and identification of intestinal ischemia may expedite the diagnosis and management of this disease and thus help to alleviate this burden on the equid population. Lactate, and specifically the L isomer, is a commonly employed biomarker in colic evaluations. A variety of other biomarkers, however, have been preliminarily evaluated for equine colic. This paper reviews currently explored biomarkers in equine medicine for colic. Ultimately, based on this review, L-lactate continues to be the most reliable marker for intestinal ischemia during colic. However, further exploration of the biomarkers included here may eventually provide the key to accelerated identification, intervention, and thus better outcomes for horses suffering from intestinal ischemia. ABSTRACT: Biomarkers are typically proteins, enzymes, or other molecular changes that are elevated or decreased in body fluids during the course of inflammation or disease. Biomarkers pose an extremely attractive tool for establishing diagnoses and prognoses of equine gastrointestinal colic, one of the most prevalent causes of morbidity and mortality in horses. This topic has received increasing attention because early diagnosis of some forms of severe colic, such as intestinal ischemia, would create opportunities for rapid interventions that would likely improve case outcomes. This review explores biomarkers currently used in equine medicine for colic, including acute phase proteins, proinflammatory cytokines, markers of endotoxemia, and tissue injury metabolites. To date, no single biomarker has been identified that is perfectly sensitive and specific for intestinal ischemia; however, L-lactate has been proven to be a very functional and highly utilized diagnostic tool. However, further exploration of other biomarkers discussed in this review may provide the key to accelerated identification, intervention, and better outcomes for horses suffering from severe colic.