Ocular FIP data sharpen treatment expectations for veterinarians

CURRENT BRIEF VERSION: New evidence is sharpening how veterinarians think about ocular feline infectious peritonitis, or FIP. A 2025 observational case series in the Journal of Veterinary Internal Medicine evaluated 20 cats with ocular involvement treated with remdesivir, GS-441524, or both, and found that ocular signs, especially uveitis, often improved with antiviral therapy, although some cats still developed serious complications such as secondary glaucoma and enucleation. The report adds needed detail to a fast-moving treatment landscape in which compounded GS-441524 has become more accessible in the U.S. since the FDA said on May 10, 2024, that it does not intend to enforce approval requirements for patient-specific compounded GS-441524 prescribed for cats with FIP under Guidance for Industry #256. Ocular disease remains especially important because it is more common in non-effusive, or “dry,” FIP and can occasionally be the dominant presenting feature, with signs ranging from keratic precipitates, iris color change, hyphema, and fibrin in the anterior chamber to retinal lesions, hemorrhage, detachment, and perivascular cuffing in the posterior segment. (pmc.ncbi.nlm.nih.gov)

Why it matters: For veterinary professionals, the study helps fill a practical gap: ocular FIP has been treatable in principle, but published data on eye-specific outcomes have been limited. The case series suggests most cats can see meaningful ophthalmic improvement with antiviral treatment, but it also underscores that ocular disease may need higher dosing, close monitoring, and regular tonometry because inflammation-related glaucoma can persist even when systemic disease improves. Broader FIP treatment data also support the shift toward regulated antiviral access, with reported response rates now commonly in the 85% to 90% range and a 307-cat retrospective study reporting an 88.6% survival rate across remdesivir and GS-441524 protocols, while current international guidance increasingly favors oral GS-441524 when feasible and reserves injectable induction for sicker cats or those unable to take oral medication. Emerging treatment work is also exploring whether higher-dose induction and objective markers such as serum amyloid A, alpha-1 acid glycoprotein, and albumin:globulin ratio trends can help guide duration more precisely than the traditional fixed 84-day course. (pmc.ncbi.nlm.nih.gov)

What to watch: Expect more attention on standardized dosing for ocular and neurologic FIP, longer-term ophthalmic follow-up, better criteria for when treatment can safely stop, and whether U.S. access expands beyond patient-specific prescriptions toward more practical clinic use. (fda.gov)