Peer-reviewed veterinary case report
Legal treatment outcomes for cats with infectious peritonitis
By Knies, Marieke et al.·Published in Journal of feline medicine and surgery·2026·Department of Clinical Sciences, Netherlands·View original on PubMed →
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Original publication title: Legal treatment of feline infectious peritonitis in the Netherlands.
- Species:
- cat
Plain-English summary
A group of 127 cats diagnosed with feline infectious peritonitis (FIP) were treated with a medication called GS-441524, sometimes after receiving another drug called remdesivir. Most of these cats were under 2 years old and showed symptoms like lethargy and loss of appetite. After at least 12 weeks of treatment, about 78% of the cats survived, with those having ocular FIP experiencing the best outcomes. While some cats had mild side effects like vomiting and diarrhea, the treatment was generally well-tolerated and effective.
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Abstract
ObjectivesThe study aimed to assess the clinical efficacy, safety and outcomes of legally prescribed and compounded GS-441524, with or without prior remdesivir, in cats with confirmed or highly suspected feline infectious peritonitis (FIP) in the Netherlands. A standardised diagnostic and treatment protocol was used to evaluate clinical response, adverse effects and prognostic factors.MethodsThis prospective, multicentre study included 127 client-owned cats with FIP, enrolled between June and November 2023 from three Dutch veterinary clinics. Diagnosis followed American Association of Feline Practitioners (AAFP)/EveryCat guidelines, incorporating clinical findings, laboratory data, imaging, cytology and RT-qPCR performed on either fine-needle aspirates or effusion. Cats were treated for a minimum of 12 weeks with oral GS-441524, with some initially receiving intravenous remdesivir before transitioning to oral therapy. Dosing was based on disease form (effusive, non-effusive, ocular, neurological). Follow-up included physical examinations and clinicopathological monitoring. Descriptive statistics, Kaplan-Meier survival analysis and Cox regression were used for data analysis.ResultsOf the 127 cats, 55.9% had effusive, 19.7% non-effusive, 16.5% ocular and 7.9% neurological FIP; 21.3% showed mixed forms. Most cats were aged under 2 years (87.4%), male (77.2%) and purebred (60.6%). Common clinical signs included lethargy (93%) and inappetence (83%). Overall survival was 78%. Ocular FIP had the highest survival (100%), while neurological FIP had the lowest (60%). Elevated serum bilirubin and creatinine concentrations at presentation were associated with reduced survival. Adverse effects were generally mild and transient, with vomiting (33%) and diarrhoea (29%) most commonly reported.Conclusions and relevanceThis study confirms that GS-441524, with or without prior remdesivir, is an effective and well-tolerated treatment for naturally occurring FIP. Clinical improvement was typically rapid; resolution of laboratory abnormalities took longer. These findings support the legal use of GS-441524 in feline practice and highlight the need for further research to refine treatment protocols.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/41339255/