Association of admission plasma D-dimer concentration with diagnosis and outcome in horses with colic.

Background: Coagulopathies detected in horses with gastrointestinal problems seem to be associated with poor outcome. Plasma D-Dimer concentration is a sensitive test for assessing coagulopathies.

Hypothesis: Plasma D-Dimer concentration tested on admission is related to diagnosis and outcome in horses with colic.

Animals: Four hundred and ninety three horses referred for evaluation of abdominal pain.

Methods: Prospective observational clinical study. Horses were grouped according to diagnosis (medical and surgical intestinal obstructions, ischemic disorders with and without intestinal resection, enteritis, peritonitis), outcome (survivors, nonsurvivors), and number of coagulopathies (normal profile, 1 or 2 coagulopathies, subclinical disseminated intravascular coagulation [DIC]). Blood samples were collected on admission and plasma D-Dimer concentration, clotting times (PT and aPTT), and antithrombin activity were determined. Positive likelihood ratios (LR+) were calculated for evaluation of D-Dimer cut-off values, which were later tested in a logistic regression model.

Results: Horses with enteritis or peritonitis had significantly (P<.001) higher plasma D-Dimer concentrations and more severe coagulopathies on admission than horses with other diagnoses. Nonsurvivors also had significantly (P<.001) higher plasma D-Dimer concentrations at presentation than did survivors, and those horses with subclinical DIC on presentation had an odds ratio (OR) 8.6 (95% confidence interval [CI], 3.3-22.5, P<.001) for nonsurvival. Finally, D-Dimer concentrations>4,000 ng/mL had a LR+ of 5.9 and an OR 8.8 (95% CI, 4.5-17.1, P<.001) for nonsurvival.

Conclusion And Clinical Importance: Plasma D-Dimer concentration measured on admission can be used to facilitate diagnosis and outcome prediction in horses with colic. A potential cut-off value for nonsurvival was found at approximately 4,000 ng/mL.