Blood and Peritoneal Lactate, Ratio and Difference, and Peritoneal Lactate to Total Solids Ratio for Detection of Intestinal Strangulating Obstructions in Horses.

Abstract

BACKGROUND: The effectiveness of the peritoneal fluid L-lactate-to-total solids ratio (PFL:PFTS) as a diagnostic marker for strangulating lesions of the small intestine (SI) and large colon (LC) has not been investigated. OBJECTIVES: Describe and compare the PFL:PTFS and blood lactate (BL), peritoneal fluid lactate (PFL) and PFL:BL difference and PFL:BL ratio of horses with SI and LC strangulating (SO) and non-strangulating (NSO) obstructions and determine sensitivity and specificity to predict SO. ANIMALS: A total of 282 horses, 117 with SI lesions (59 classified as SINSO and 58 as SISO), and 165 with LC lesions, 126 categorized as LCNSO and 39 as LCSO. METHODS: Retrospective study. Receiver operating characteristic (ROC) curves were generated to identify optimal cut-off points to maximize sensitivity and specificity to predict SO. RESULTS: A PFL:PFTS ratio of 2.9 had fair (area under the curve [AUC], 0.76; 95% confidence interval [CI], 0.67-0.84) ability to discriminate between SISO and SINSO, with sensitivity of 66.7% and specificity of 78.3% to predict SISO. A PFL: PFTS ratio of 3.6 had good ability to discriminate between LCSO and LCNSO (AUC, 0.84; 95% CI, 0.78-0.90) with sensitivity and specificity of 78% and 81% to predict LCSO, respectively. Peritoneal fluid lactate, PFL:BL difference, and PFL:BL ratio also had a low to moderate sensitivity to predict ischemic strangulating lesions of the SI and LC. CONCLUSION AND CLINICAL IMPORTANCE: Strangulating obstructions are critical conditions requiring prompt intervention. The low to moderate sensitivity identified suggests that PFL, PFL:BL difference and ratio, and PFL:PFTS ratio should be interpreted with clinical signs and the response to initial treatment to determine SO accurately.