Differentiation between dogs with thrombosis and normal dogs using the overall hemostasis potential assay.

OBJECTIVE: To determine whether the overall hemostasis potential (OHP) and calibrated automated thrombogram (CAT) were significantly different between dogs with thrombosis and normal dogs. ANIMALS: Ten dogs with clinical evidence of thromboembolic disease had both OHP and CAT performed. Forty healthy control dogs had OHP performed, and 23 of these also had CAT performed. MEASUREMENTS AND MAIN RESULTS: Dogs with thrombosis had significantly higher OHP (P = 0.003), overall coagulation potential (P = 0.0001), and maximum optical density (Max OD, P < 0.0001) than normal dogs, and a significantly longer delay in the start of clot formation (P = 0.01). Max OD was higher than established reference intervals in 80% of the dogs with thrombosis. Using the CAT assay, dogs with thrombosis had a significantly longer lag time than normal dogs (P < 0.001). Plasma fibrinogen concentration correlated positively with overall coagulation potential, OHP, Max OD, and the slope of the OHP curve (P < 0.05), and was increased in 90% of dogs with thrombosis. CONCLUSIONS: The OHP assay findings were significantly different between normal dogs and those with thrombosis. CAT did not detect any significant differences between these populations of dogs, other than the lag time of the assay.

Evaluation and modification of the overall hemostasis potential assay for use with canine plasma.

OBJECTIVE: To optimize the overall hemostasis potential (OHP) assay for use with canine platelet-poor plasma and determine reference intervals in healthy dogs. ANIMALS: 40 healthy dogs. PROCEDURES: Blood was collected from the dogs into citrated tubes, and platlet-poor plasma was obtained. The OHP assay and standard coagulation assays (prothrombin time, activated partial thromboplastin time, and fibrinogen concentration) were performed for each sample. The OHP assay outputs were tested for correlations with results of the standard coagulation assays, age, and sex. RESULTS: Modifications to the published methodology for the OHP assay were required for use with canine plasma, with less coagulation activator (thrombin) and more fibrinolysis activator (tissue plasminogen activator) than used with human plasma. Male dogs had a higher OHP than did females. High fibrinogen concentrations were associated with increases in maximum optical density, OHP, and overall coagulation potential, and reduced prothrombin time was associated with increases in maximum optical density, overall coagulation potential, OHP, and maximum slope. CONCLUSIONS AND CLINICAL RELEVANCE: Results supported the use of the OHP assay as an accessible, cost-effective global coagulation assay. Further research is required to determine its clinical application as an alternative to thromboelastography or thrombin generation assays.