The purpose of this randomized, controlled, blinded study was to evaluate the effect of orally administered Yunnan Baiyao on measures of blood loss and coagulation in dogs undergoing nasal biopsy. Nineteen client-owned dogs presenting for nasal biopsy were randomized to receive Yunnan Baiyao or lactose placebo. All dogs had baseline blood pressure, platelet count, prothrombin time and activated partial thromboplastin time performed at presentation and a buccal mucosal bleeding time performed before and after capsule administration. Some dogs also had thromboelastography and blood loss measurements (9/19), just thromboelastography (6/19), and only blood loss (4/19) measurements performed. Measurements of blood loss included total blood loss, blood loss as a percentage of body weight and time to stop bleeding. Results of the study demonstrated time to stop bleeding was significantly shorter (p<0.05) in the YB group (300 ± 12 sec) compared to the control group (367 ± 9 sec) and was not influenced by underlying disease process. Although there was decreased blood loss as a percentage of body weight in the Yunnan Baiyao treated group (14%) when compared to the control group (25%), the difference did not reach statistical significance. There was no effect of Yunnan baiyao on measures of coagulation including buccal mucosal bleeding time or thromboelastography. The results of this study support the use of Yunnan baiyao prior to nasal biopsy in dogs. Further studies are needed to determine the clinical use of Yunnan baiyao for other procedures and diseases associated with increased risk of hemorrhage.