Retrospective evaluation of shortened prothrombin time or activated partial thromboplastin time for the diagnosis of hypercoagulability in dogs: 25 cases (2006-2011).

Abstract

OBJECTIVE: To evaluate the relationship between shortened prothrombin time (PT) or activated partial thromboplastin time (aPTT) values, clinical findings associated with hypercoagulability, suspicion of pulmonary thromboembolism (PTE), D-dimer concentrations, and thromboelastogram (TEG) indices. DESIGN: Retrospective observational study from 2006 to 2011. SETTING: University veterinary teaching hospital. ANIMALS: Twenty-three dogs with TEG tracings and shortened PT or aPTT values and 23 control dogs with TEG tracings and normal PT and aPTT values. MEASUREMENTS AND MAIN RESULTS: Parameters evaluated included signalment, coagulation testing results (PT, aPTT, D-dimer concentration), TEG measurements (R, K, &#x3b1;, maximal amplitude) and calculated clotting index, findings of clinical hypercoagulability (thrombosis of intravenous/intra-arterial catheters, vessel thrombosis, and suspected PTE). Dogs with shortened PT or aPTT had significantly more thrombus formation (P = 0.038), suspicion of PTE (P < 0.001), and increased D-dimer concentration (P < 0.001) compared to dogs with normal PT and aPTT values. There were no significant findings when compared to TEG values. CONCLUSIONS: A shortened PT or aPTT in dogs may be indicative of a hypercoagulable state as evidenced by an increased incidence of thrombosis, frequency of suspected PTE, and increased circulating D-dimers. A prospective study is warranted to further evaluate the use of PT and aPTT to diagnose hypercoagulable states.