A field test for endotoxin in the horse

Abstract

Summary Equine endotoxemia was diagnosed with a new rapid test for endotoxin in whole blood (Etox-Dx, KenVet, Ashland, OH). Test results of 66 horses referred to an equine clinic were compared to clinical diagnosis of endotoxemia. Samples from 55 horses examined for colic in the field were tested. The test was compared to a whole blood Limulus amebocyte lysate assay. Between 82% and 95%, of endotoxin (gram-negative bacterial lipopolysaccharide, LPS) in equine blood was found to be associated with formed elements and removed by separating serum or plasma. Detecting endotoxin in whole blood accurately assessed its presence or absence. Overall agreement between endotoxemia diagnosis by clinical signs and assay was 29%. Clinical diagnosis and test result agreed in 77% of endotoxic cases. With cases clinically diagnosed as negative for endotoxin, 67% were positive with the test. Overall, positive endotoxin test results were obtained with 74% of hospitalized cases compared to a 45% positive rate cases in the field. These data suggest that the test provides direct diagnosis of endotoxemia that may be of particular value in horses without clinical symptoms of endotoxemia.