The buccal mucosal bleeding time.

Abstract

289 Steven L. Marks, BVSc, MS, MRCVS, Diplomate ACVIM Bleeding occurs when vascular integrity is disrupted. Hemostasis is accomplished by vascular reaction, formation of a platelet plug, and activation of the coagulation cascade. In general, hemostasis can be divided into primary and secondary systems. The primary hemostasis system relies on the dynamic interaction between the vessel wall, vascular endothelium, and platelets. Exposure of vascular subendothelium triggers activation of von Willebrand’s factor, which links platelets to the site of vessel injury. Once platelets have adhered to the area and form the platelet plug, they assist in activation of the intrinsic pathway of the coagulation cascade or secondary hemostasis. Several commonly used “bleeding times” are utilized in veterinary medicine to evaluate patients for hemostatic disorders. The one-stage prothrombin time (OSPT), activated partial thromboplastin time (APTT), activated clotting time (ACT), and the buccal mucosal bleeding time (BMBT) are parameters that provide the veterinary clinician with critical information about the bleeding or at-risk patient. All of the tests mentioned, other than the BMBT, are used to evaluate secondary hemostasis. The BMBT is used along with the platelet count to evaluate primary hemostasis. The BMBT is a valuable diagnostic tool that is cost effective and easy to use in the general practice setting. The BMBT is used to evaluate hemorrhage from a standardized incision on the oral mucosa. It is performed using a disposable, single-use, spring-loaded lancet [Figure 1]. The procedure is performed with the dog restrained in lateral recumbency. The upper lip is everted and held in place by a length of roll gauze [Figure 2]. The gauze acts to maintain the eversion of the lip and to cause some vascular congestion. The lancet is placed against the buccal mucosa in a vertical direction directly above the maxillary canine tooth. Depressing the trigger [Figure 1] then activates the lancet. The lancet causes a controlled incision, which will readily bleed. Once the incision is made, the time should be noted and monitored. Circular filter paper is used to blot the blood as it drips from the incision. The filter paper should be held approximately 1 to 2 mm away from the incision, using care not to disrupt the clot formation. It is important to not allow the blood to drip into the animal’s mouth, as this may lead to agitation and movement. The end point of this test is when the incision stops bleeding. The published normal range for the BMBT in the dog is less than three minutes. Prolongation of the BMBT can occur with thrombocytopenia, thrombocytopathy, and von Willebrand’s disease. Clinical findings associated with abnormalities of primary hemostasis include superficial cutaneous bleeding, petechiation, ecchymosis, epistaxis, and mucosal bleeding of the gastrointestinal tract and urogenital tract (hematuria). If The Buccal Mucosal Bleeding Time