PLASMA VON-WILLEBRAND-FACTOR ANTIGEN CONCENTRATION AND BUCCAL MUCOSALBLEEDING-TIME IN DOGS WITH EXPERIMENTAL HYPOTHYROIDISM

This study was undertaken to investigate the effects of hypothyroidism on buccal mucosal bleeding time and von Willebrand factor antigen (vW f:Ag) concentrations. Hypothyroidism was induced in 8 adult dogs by ad ministration of iodine 131. Four healthy dogs acted as controls, Measu rement of plasma vWf:Ag and serum thyroxine and triiodothyronine conce ntrations, and buccal mucosal bleeding time were made before induction of hypothyroidism, for 23 weeks after I-131 administration, and durin g 5 weeks of levothyroxine supplementation. No significant changes in buccal mucosal bleeding times were noted during the study, After an in significant increase in vWf:Ag concentration in hypothyroid dogs, levo thyroxine treatment was associated with a significant decrease in vWf: Ag concentration in hypothyroid dogs when compared with controls, Resu lts of this study suggest that hypothyroidism does not induce acquired von Willebrand's disease or significant defects in primary hemostasis . Copyright (C) 1996 by the American College of Veterinary Internal Me dicine.