Lactate Dehydrogenase Activity in Abdominal Fluid From Horses With Colic

The purpose of this study was to determine whether lactate dehydrogenase (LDH) activity in abdominal fluid could be used as a prognostic indicator in horses with colic. Lactate dehydrogenase activity was measured in 27 abdominal effusions from horses with colic presented to Murdoch University Veterinary Teaching Hospital using three different LDH test methods. Lactate in effusions was also measured in 11 of the horses. Lactate dehydrogenase activity was significantly different for each test method used—the ratio of Randox wet chemistry LDH lactate to pyruvate:Randox wet LDH pyruvate to lactate (P-L):IDEXX dry chemistry P-L was approximately 1:2:4. Lactate dehydrogenase activity in the abdominal effusions was significantly higher with all methods in the horses that died or were euthanized because of abdominal sepsis or advanced neoplasia than in those that survived after treatment for colic signs because of mechanical obstructions or nonseptic abdominal inflammation. Lactate dehydrogenase activity showed moderate-to-good correlation (r = 0.73 to 0.86) with lactate concentration of the fluid. In conclusion, LDH activity in abdominal fluid may be a useful prognostic test in horses with colic. The test method for LDH measurement must be known and remain constant for meaningful interpretation. Significantly higher levels of LDH activity may be present in horses with colic because of sepsis or advanced neoplasia than in those with colic because of nonseptic inflammation or mechanical obstructions that may respond to treatment.