Laboratory evaluation begins with a comprehensive health profile (CBC, biochemical profile, and urinalysis) and basic coagulation profile (platelet count, PT, PTT, fibrinogen concentration, and d-dimer test for FDPs). A von Willebrand factor assay also may be indicated, depending on the signalment of the patient, breed, and type of hemorrhage. A mucosal bleeding time or toenail transection bleeding time may also provide helpful information (see Antech News, March 1997 for a description of these procedures).

Proper collection and handling of blood samples for evaluation of hemostasis is critical for obtaining reliable results. Clean venipuncture, rapid transfer of blood into Vacutainer® tubes, and sufficient filling of tubes is important. The blue top tube (BTT) should be filled to at least 75% and preferably to full capacity. Centrifugation and transfer of plasma into a plastic tube is preferred if transport to the lab will take more than 12 hours. Freezing plasma is not required, but it should be kept cold. Samples being mailed to the lab should be shipped overnight with frozen cold packs. Plasma von Willebrand factor can be measured in samples collected into either BTT or full lavender top tubes, following the above guidelines (see Antech News, March and November, 1997).

Geraldine Arriola, DVM, Animal Medical Clinic, Mesa, AZ submitted this case report.