Dual antithrombotic therapy gains attention in high-risk cats
Bottom line
A recent VETgirl podcast published March 23, 2026, spotlights a 2022 retrospective case series examining dual antithrombotic therapy with clopidogrel and rivaroxaban in cats with thromboembolic disease. The underlying study, from investigators at the University of California, Davis, reviewed 32 outpatient cats treated over five years, most with hypertrophic cardiomyopathy or remodeled HCM, and found that the combination was associated with a low reported rate of clinically significant adverse events and a 16.7% recurrence rate among cats treated after an arterial thromboembolism event. No cat started on dual therapy for spontaneous echocardiographic contrast or intracardiac thrombus developed a new arterial thromboembolism while on treatment. (podcasts.apple.com)
Why it matters: For veterinary professionals, the study adds some much-needed clinical support to a strategy that has already been reflected in ACVIM consensus guidance for very high-risk cats: using clopidogrel as the foundation of thromboprophylaxis, with consideration of adding an oral factor Xa inhibitor such as rivaroxaban in selected cases. The evidence is still limited, retrospective, and from a single center, but it helps fill a gap between guideline recommendations and real-world feline cardiology practice, especially for cats with prior arterial thromboembolism, intracardiac thrombi, or marked spontaneous echocardiographic contrast. (academic.oup.com)
What to watch: The key next step is stronger prospective evidence, because current support for dual therapy in cats remains based on retrospective data, while earlier controlled evidence established clopidogrel, not combination therapy, as superior to aspirin for secondary prevention after feline arterial thromboembolism. (sciencedirect.com)
A new VETgirl podcast is drawing attention to a treatment approach many feline clinicians already consider in the highest-risk cardiac cases: dual therapy with clopidogrel and rivaroxaban for cats with thromboembolic disease. The episode, published March 23, 2026, reviews a 2022 Journal of Feline Medicine and Surgery case series that suggests the combination may be reasonably well tolerated and may help reduce recurrent events in selected cats. (podcasts.apple.com)
The clinical backdrop is familiar, and grim. Feline arterial thromboembolism is one of the most devastating complications of cardiomyopathy, particularly hypertrophic cardiomyopathy. The 2020 ACVIM consensus statement on feline cardiomyopathies recommends clopidogrel for cats at risk of arterial thromboembolism and says additional antithrombotic drugs, including an oral factor Xa inhibitor, can be considered in cats believed to be at very high risk. That recommendation, however, has rested on limited feline-specific evidence, creating a gap between expert guidance and published outcomes data. (academic.oup.com)
The Lo et al. study aimed to address part of that gap. Investigators retrospectively reviewed 32 client-owned cats treated at UC Davis between June 2015 and August 2020 with clopidogrel at 18.75 mg PO every 24 hours and rivaroxaban at 2.5 mg PO every 24 hours. Cats were placed on dual therapy after an arterial thromboembolism event, for intracardiac thrombus, for spontaneous echocardiographic contrast, or for overlapping indications. At therapy initiation, 30 of 32 cats had HCM or remodeled HCM, and 26 had congestive heart failure. (journals.sagepub.com)
In terms of outcomes, five cats had adverse effects considered potentially medication-related, typically minor bleeding signs such as epistaxis, hematemesis, hematochezia, or hematuria, and no cat required hospitalization because of those events. Among the 18 cats started on dual therapy after an arterial thromboembolism event, three had recurrence while on treatment, for a recurrence rate of 16.7%. Notably, none of the cats started on the combination for spontaneous echocardiographic contrast or intracardiac thrombi developed a new arterial thromboembolism during follow-up. Median survival after starting dual therapy was 257 days overall and 502 days for cats whose indication included arterial thromboembolism. (journals.sagepub.com)
The study’s importance is partly about timing. Before this report, the best-controlled evidence in the field was the FAT CAT trial, which showed clopidogrel outperformed aspirin for secondary prevention of cardiogenic arterial thromboembolism in cats that survived an event. The dual-therapy paper does not replace that trial, but it builds on it by evaluating what many cardiologists have done when clopidogrel alone may not seem sufficient, especially in cats with prior thromboembolism or echocardiographic evidence of marked thrombotic risk. (sciencedirect.com)
There doesn’t appear to be a large body of formal outside commentary tied specifically to the VETgirl episode, but the study aligns with broader educational messaging in feline cardiology. The ACVIM statement explicitly notes that clopidogrel does not eliminate arterial thromboembolism risk and that additional antithrombotic drugs may be considered in very high-risk cats, albeit with low-level evidence. That makes this case series less of a practice-changing shock and more of an evidence point supporting what has, until now, often been an extrapolated or experience-based escalation strategy. (academic.oup.com)
Why it matters: For general practitioners, emergency clinicians, and cardiologists, the practical takeaway is cautious reassurance. Dual clopidogrel-rivaroxaban therapy may be a reasonable outpatient option in carefully selected cats with previous arterial thromboembolism, intracardiac thrombus, or spontaneous echocardiographic contrast, particularly when pet parent counseling includes the possibility of bleeding events, medication adherence challenges, and the still-limited quality of evidence. The study also underscores a recurring reality in feline thrombosis management: many decisions still depend on risk stratification, clinician judgment, and close follow-up rather than robust comparative trials. (journals.sagepub.com)
What to watch: The field still needs prospective, ideally multicenter comparative studies to determine whether dual therapy truly improves recurrence and survival outcomes over clopidogrel alone, and whether particular feline subgroups benefit most. Until then, this paper is likely to serve as supportive, but not definitive, evidence for escalation in the highest-risk cats. (journals.sagepub.com)