In this VETgirl blog, we demonstrate how to perform a buccal mucosal bleeding time (BMBT) in a dog to test for von Willebrands factor (vWF) disease. Keep in mind that a BMBT will test for primary hemostasis. Prior to performing a BMBT, a coagulation panel and platelet count should be performed. Prothrombin time (PT) and activated partial thromboplastin time (aPTT) should not be affected with vWF, as there is no factor deficiency, per se. Likewise, platelet count should be assess prior to performing a BMBT, as this test is affected by thrombocytopenia. In other words, if the patient's platelet count is < 40-50,000, a BMBT isn't recommended (as it will be prolonged just from thrombocytopenia alone).
1) Gently restrain the patient in lateral recumbency
2) In dogs, tie a gauze strip around the muzzle to fold the upper lip up, thereby exposing the mucosal surface. Tie this securely to hold the lip up, but not too tight as to occlude blood flow.
3) Choose an area to perform the BMBT that is free of visible blood vessels.
4) Remove the guard from the top of the JorVet lancet, making sure not to depress the tab (which will release the scalpel blade).
5) While holding the lancet closely up to the mucosal surface with light pressure, depress the tap to release the scalpel bladder. Once you depress this, the blade quickly incises the surface of the mucosa and retracts back into the device.
6) Throw away the JorVet lancet after single use (No, seriously!).
7) Once the incision starts freely bleeding, begin the timer. Using your filter paper (VETgirl uses fancy coffee filters instead), gently blot the excess blood but make sure not to touch the incision directly or disrupt clot formation. Once the incision is no longer bleeding and the paper no longer soaks up blood, you can stop the timing.
Depending on what reference source you use, normal value ranges are listed below:
Dogs: 1.5-4 minutes
Cats: 1-2.5 minutes
1. Cornell University Veterinary Diagnostic Laboratory: Bleeding time tests
2. Jergens AE, Turrentine MA, Kraus KH, et al. Buccal mucosa bleeding times of healthy dogs and of dogs in various pathologic states, including thrombocytopenia, uremia, and von Willebrand's disease. Am J Vet Res 1987;48(9):1337-1942.