Evaluation of a point-of-care coagulation analyzer (Abaxis VSPro) for identification of coagulopathies in dogs

Objective - To evaluate the ability of the Abaxis VSPro, a point-of-care analyzer that measures prothrombin time (PT) and activated partial thromboplastin time (aPTT), to identify dogs with coagulopathies caused by administration of anticoagulants. Setting - Veterinary teaching hospital. Animals - Six healthy adult dogs that are part of a preexisting research colony. One dog was not included in the warfarin portion of the study. Measurements and Main Results - Unfractionated heparin (UFH, 50 U/kg IV once then 300 U/kg SQ q 8 h) was administered to prolong aPTT. Citrated whole blood was used for PT and aPTT analyses with the VSPro and were run in duplicate. The VSPro results were compared to PT and aPTT measured in plasma with a standard benchtop coagulometer (AMAX Destiny). A washout period of at least 24 hours followed. Once dogs had normal PT and aPTT values, warfarin was administered (0.25-0.30 mg/kg PO) once then (0.15 mg/kg PO) as needed up to every 12 hours to prolong PT values. Seventy separate samples were evaluated for PT and 73 samples for aPTT. Pearson correlation coefficients (PCC) for replicate VSPro measures of PT and aPTT were 0.941 and 0.891, respectively (P < 0.001). The PCC between VSPro and AMAX was 0.578 for PT and of 0.865 for PTT (P < 0.001). Receiver operating characteristic (ROC) analysis indicated a maximum sensitivity and specificity for diagnosis of coagulopathy (by AMAX) at VSPro PT value of 21.6 seconds (sensitivity 72%, specificity 86%) and a maximum sensitivity and specificity at VSPro aPTT of 105.3 seconds (sensitivity 93%, specificity 89%). The positive predictive value for PT and aPTT were 84% and 89%, respectively. Conclusions - The Abaxis VSPro showed acceptable correlation with clinical laboratory tests, and is a useful POC device for identification of animals with abnormalities in PT or aPTT.