A prospective evaluation of rivaroxaban on haemostatic parameters in apparently healthy dogs

The purpose of this study was to determine the effect of rivaroxaban ( RIV ) on haemostatic parameters assessed by prothrombin time ( PT ), activated partial thromboplastin time ( aPTT ) and kaolin‐activated thromboelastography ( TEG ) in apparently healthy dogs administered 1 mg kg −1 orally once daily for 1 week. Eleven dogs had a baseline complete blood count ( CBC ), fibrinogen, platelet count, serum chemistry profile, PT , aPTT , and TEG performed. Each dog was then administered approximately 1.0 mg kg −1 of RIV orally once daily for 1 week and the CBC , fibrinogen, platelet count, serum chemistry profile, PT , aPTT , and TEG was re‐evaluated. Any side effects attributed to RIV were noted at this time. One dog was excluded due to identification of a macrocytic thrombocytopenia on pre‐treatment blood work. The remaining 10 enrolled dogs completed the study. Dogs received a median dose of 1.02 mg kg −1 (range 0.94–1.17 mg kg −1 ) of RIV once daily and was associated with a significant increase in pulse, packed cell volume, total solids, platelet count, fibrinogen and a significant decrease in mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration. There was no significant change in PT , aPTT or any TEG parameters. The RIV appeared well tolerated with one dog having one episode of vomiting on day 4 but otherwise no other side effects were identified clinically or on recheck blood work. The results of this study suggests that RIV at a dose of 1 mg kg −1 orally once daily is safe and well tolerated but does not cause a significant prolongation of PT , aPTT or TEG parameters.