Use of enzyme-linked immunosorbent assay to measure thrombin-antithrombin III complexes in horses with colic

To evaluate new ELISA for measurement of thrombin-antithrombin III (TAT) concentration, and to correlate the values to other tests of hemostasis in horses with colic.

Plasma TAT concentration and 8 other hemostasis analytes were measured in horses with colic at hospital admission and during the next 4 days. Retrospectively, data were analyzed by outcome, broad-category diagnosis, and clinical management, and for correlation between TAT and other assays.

100 horses with colic.

Plasma samples were evaluated for TAT, fibrinogen, and fibrin degradation products concentrations; antithrombin III (ATIII), protein C, alpha 2-antiplasmin, and plasminogen activities; prothrombin time (PT); and activated partial thromboplastin time.

Changes were indicative of a hypercoagulable state, most severe in nonsurviving horses, characterized by increased TAT concentration; decreased ATIII, protein C, and plasminogen activities; and increased PT. Nonsurvivors had significantly increased TAT concentration compared with that in survivors, without regard to sample collection time; however, compared over time, TAT was significantly increased only at admission. Highest TAT concentration was in nonsurvivors with inflammatory intestinal lesions. There was significant negative correlation between TAT and ATIII, protein C, alpha 2-antiplasmin, and plasminogen values, and significant positive correlation between TAT and PT, and fibrin degradation products values.

Plasma TAT reflects the current state of coagulation system activation and is a good assay for early diagnosis of the hypercoagulable state in horses with the most severe forms of colic.

Measurement of equine TAT provides further information to characterize the hypercoagulable state in horses to aid in case management.