Use of multiple admission variables better predicts intestinal strangulation in horses with colic than peritoneal or the ratio of peritoneal:blood l-lactate concentration.

Abstract

BACKGROUND: Early identification of strangulating obstruction (SO) in horses with colic improves outcomes, yet early diagnosis of horses requiring surgery for SO often remains challenging. OBJECTIVES: To compare blood and peritoneal fluid l-lactate concentrations, peritoneal:blood l-lactate ratio, peritoneal minus blood (peritoneal-blood) l-lactate concentration and other clinical variables for predicting SO and SO in horses with small intestinal lesions (SO-SI) and then to develop a multivariable model to predict SO and SO-SI. STUDY DESIGN: Retrospective cohort. METHODS: A total of 197 equids admitted to a referral institution for colic between 2016 and 2019 that had peritoneal fluid analysis performed at admission were included. Twenty-three admission variables were evaluated individually for the prediction of a SO or SO-SI and then using multivariable logistic regression. Odds ratios (ORs) with 95% confidence intervals (CI) and area under the curve of the receiver operator characteristic (AUC ROC) were calculated. RESULTS: All variables performed better in the model than individually. The final multivariable model for predicting SO included marked abdominal pain (OR 5.31, CI 1.40-20.18), rectal temperature (OR 0.30, CI 0.14-0.64), serosanguineous peritoneal fluid (OR 35.34, CI 10.10-122.94), peritoneal-blood l-lactate (OR 1.77, CI 1.25-2.51), and peritoneal:blood l-lactate ratio (OR 0.36, CI 0.18-0.72). The AUC ROC was 0.91. The final multivariable model for predicting SO-SI included reflux volume (OR 0.69, CI 0.56-0.86), blood l-lactate concentration (OR 0.43, CI 0.22-0.87), serosanguineous peritoneal fluid (OR 4.99, CI 1.26-19.74), and peritoneal l-lactate concentration (OR 3.77, CI 1.82-7.81). MAIN LIMITATIONS: Retrospective, single-hospital study design. CONCLUSIONS: Blood and peritoneal fluid l-lactate concentrations should be interpreted in conjunction with other clinical variables. The relationship between peritoneal and blood l-lactate concentration for predicting SO or SO-SI was complex when included in a multivariable model. Models to predict SO probably vary based on lesion location.