Monitoring of Rivaroxaban Therapy in Hypercoagulable Dogs.

Abstract

BACKGROUND: Measurement of rivaroxaban efficacy using the rivaroxaban-specific anti-Xa assay (raXa) can be used for monitoring in veterinary medicine. Detection of rivaroxaban efficacy using other hemostatic tests would make monitoring timelier and more accessible. OBJECTIVES: Compare results of raXa with prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen concentration, tissue factor (TF) and kaolin-activated thromboelastography (TEG), and thrombin generation (TG) in hypercoagulable dogs. ANIMALS: Twelve client-owned dogs, diagnosed with hypercoagulability or thromboembolic disease, and prescribed rivaroxaban, were recruited from a tertiary referral hospital from 2020 to 2022. METHODS: Prospective clinical trial. Jugular vein blood samples were collected before treatment, and 1&#x2009;week and 1-3&#x2009;months after initiation of rivaroxaban therapy. Hemostatic tests were performed at each visit (3&#x2009;h after rivaroxaban dosing). TG curve parameters lag time, endogenous thrombin potential (ETP), peak, and time to peak (ttpeak) were assessed. RESULTS: There was a significant linear relationship between raXa and PT (r&#x2009;=&#x2009;0.74, p&#x2009;<&#x2009;0.001), ETP (r&#x2009;=&#x2009;0.83, p&#x2009;<&#x2009;0.001), lag time (r&#x2009;=&#x2009;0.87, p&#x2009;<&#x2009;0.001), peak (r&#x2009;=&#x2009;0.86, p&#x2009;<&#x2009;0.001), and ttpeak (r&#x2009;=&#x2009;0.86, p&#x2009;<&#x2009;0.001). There was a weak linear relationship between raXa and kaolin-activated TEG parameter reaction time (R) (r&#x2009;=&#x2009;0.49, p&#x2009;=&#x2009;0.026). There was no significant relationship between raXa and aPTT, fibrinogen concentration and the remainder of the TEG variables (p&#x2009;>&#x2009;0.05). CONCLUSION AND CLINICAL IMPORTANCE: PT and TG correlated with raXa. PT performed at a reference laboratory appeared to be a convenient method to monitor a small cohort of dogs receiving rivaroxaban therapy.