Clinical Trial

Study to compare the effectiveness of two different medications for preventing recurrent blood clots in cats

Department: Cardiology Service


A multicenter study to determine the utility of clopidogrel versus rivaroxaban for prevention of recurrent feline aortic thromboembolism

What we are looking for: Cats diagnosed with thromboembolism (blood clot) due to cardiac disease

Benjamin Brainard, VMD, DACVAA, DACVECC (emergency/critical care faculty)
Gregg Rapoport, DVM, DACVIM (cardiology faculty)
Amanda Erikson, DVM, DACVIM (cardiology faculty)

If interested please call the Small Animal Teaching Hospital at 706-542-3221 and ask to leave a message for one of the investigators listed above. Referring veterinarians may call the small animal referral coordinator at 706-542-5362. This is designed as a multicenter study; the enrolled cat does not necessarily have to be evaluated at the UGA Small Animal Teaching Hospital. Additional information is available at

Study description: The purpose of this study is to compare the efficacy of two different drugs for preventing recurrent thromboembolism (blood clots) in cats who have experienced and recovered from a prior clot event. Also called “saddle thrombus,” thromboembolism is common in cats who have cardiac disease. By describing the efficacy of these drugs for prevention of blood clots, the occurrence of thromboembolism can be decreased.

Client-owned cats that have been diagnosed with a thromboembolism due to cardiac disease are eligible for enrollment in the study. Cats must be stabilized and recovered from the initial thromboembolism and have cardiac disease diagnosed by a veterinary cardiologist. If cardiac disease is suspected, the cats may also be referred for evaluation by the UGA cardiology service for screening for inclusion. Cats with significant other systemic disease requiring treatment (e.g. cancer, severe infection) are not eligible. Cats that require medication for cardiac disease are eligible.

Study participation will last 2 years and include the collection of a small blood sample (1 tsp) at four time points, in addition to reevaluation by a veterinary cardiologist at 2, 6, 12, and 18 months after enrolment. After recruitment, cats will receive a two-year supply of either clopidogrel or rivaroxaban, two drugs that decrease the tendency of the body to form blood clots. In addition, the study will provide a monetary stipend to support the cardiac reevaluations. Owners will be required to fill out an online survey on their cat’s activity every 2 months for the duration of the study. The medications will be mailed to the owner following completion of the survey, at no cost to the owner.

Duration of study: The study is ongoing and will continue until a total of 90 cats with heart disease are enrolled. The study is expected to be completed by January 2019.

Potential benefits to veterinary medicine: The effect of targeted anticoagulant therapy to prevent recurrence of thromboembolism in cats with heart disease has not been definitively determined. The results of this study will hopefully be useful for cats with heart disease who have had a thromboembolism as well as for those cats who may be at risk of this devastating event.