ENZYME-LINKED-IMMUNOSORBENT-ASSAY FOR THROMBIN-ANTITHROMBIN-III COMPLEXES IN HOUSES

Objectives-To adapt and characterize a human ELISA kit to quantify thr ombin-antithrombin III (TAT) complexes in horses, and to evaluate TAT as a marker for hypercoagulation in horses. Animals-29 clinically norm al horses used as controls, and 4 ill horses used to evaluate assay fo r known causes of hypercoagulation. Procedure-A commercially available human sandwich-type ELISA kit with 2 antibodies against human thrombi n and antithrombin III that bind selectively to their corresponding TA T antigenic sites was used. Equine TAT standards were made from purifi ed equine thrombin acid antithrombin III. Proteins diluted in a phosph ate-buffered saline solution containing 0.1% Tween and 1 U of heparin/ ml were used to establish standard curves, Reference intervals had TA T concentration in citrated equine plasma, and intra- and interassay c oefficients of variation were determined. Results-Mean +/- SD values w ere 3.95 +/- 1.93 mu g/L, with median of 3.18 mu g/L and range of 1.95 to 9.03 mu g/L. One horse with cecal perforation had TAT concentratio n of 174.30 mu g/L, and a horse infused IV with endotoxin had TAT conc entration of 62.98 mu g/L 12 hours after infusion. Conclusions-The dat a suggest that human TAT ELISA kits can be used to measure TAI concent ration in citrated equine plasma, and that TAT is a marker for hyperco agulation in horses. Clinical Relevance-Assays for equine TAT many hel p to further characterize the hypercoagulable state in horses.