Blood and peritoneal lactate in equine colic: application in emergency care and construction of a decision tree

The objective of this retrospective study was to determine whether blood lactate (BL) and peritoneal lactate (PL) are correlated with heart rate, BL-to-PL ratio and dehydration severity in horses with colic that died within or survived beyond 24 hours of hospital admission, and to construct decision trees aimed at predicting short-term mortality using machine learning algorithms. Medical records (n = 339) from the database of the Veterinary Hospital of the School of Veterinary Medicine and Animal Science, University of S & atilde;o Paulo (FMVZ-USP) of horses admitted with colic were retrieved. Correlations between variables of interest were investigated using the Pearson's or the Spearman's correlation coefficient. The level of significance was set at 5% (p<0.05). Algorithms used belong to the WEKA environment and were compared using the paired t test (p<0.05). Peritoneal lactate values were strongly and negatively (p<0.05) correlated with BL:PL ratio, and moderately and positively (p<0.05) correlated with percentage of dehydration. Two decision trees with more than 80% accuracy in predicting mortality were constructed and can be used to inform clinicians about the probability of survival beyond the first 24 hours of hospitalization.