• Equine;
  • Prognostic indicator;
  • SIRS


Serial measurement of lactate concentration is utilized for therapeutic and prognostic purposes in human critical care. The prognostic value of serial lactate measurement in equine acute colitis warrants investigation.


Serial lactate concentrations are predictive of outcome in horses with colitis.


A total of 101 horses with colitis.


Retrospective study. Plasma l-lactate concentrations were measured at admission and at 4–8 and 24 hours after admission. Associations between admission, early (4–8 hours) and late (24 hours) lactate concentrations, and survival status were determined. The percent reduction in lactate concentration between admission and the early time point, and between admission and the late time point, was calculated. Using a cutoff value, associations between percent reduction in lactate and survival status and associations between percent reduction in lactate and clinical and clinicopathologic data were determined.


There was no association between admission plasma lactate concentration and survival status (P = .26). The 4–8 and 24 hour after admission lactate concentrations were associated with survival status (P = .023, .013, respectively). Lactate cutoffs of ≤2.3 and ≤1.5 mmol/L had the maximum sensitivity and specificity for predicting survival at the 4–8 and 24 hour time points, respectively. When lactate reduction ≥30% at 4–8 hours and ≥50% at 24 hours after admission were used as the cutoffs, the percent reduction of lactate concentration was significantly associated with survival (P = .012 and .019, respectively).

Conclusion and Clinical Importance

The prognostic ability of serial measurement of blood lactate concentration warrants prospective study as a measure of therapeutic response in horses with colitis.