New evidence sharpens the picture on ocular FIP treatment

Ocular FIP treatment is moving from anecdote toward a more evidence-based discussion, with new and recent studies helping clarify how cats with eye involvement respond to antiviral therapy, especially GS-441524 and remdesivir. A newly indexed prospective study from the University of Zurich followed 118 cats with FIP treated with GS-441524 specifically to assess ocular manifestations, while a 2025 observational case series reported that uveitis associated with ocular FIP responded effectively in 82% of 20 cats treated with remdesivir alone or combined with GS-441524. Clinician education sources are also helping translate that evidence into practice, emphasizing that ocular disease may be the dominant presentation in some cats and can include anterior uveitis, keratic precipitates, iris color change, dyscoria or anisocoria, hyphema, hypopyon, fibrinous exudate, retinal lesions, hemorrhage, vascular tortuosity, retinal detachment, or perivascular cuffing. That builds on a broader shift in FIP care: once considered almost uniformly fatal, the disease is now increasingly managed with compounded antivirals in clinical practice, including in the U.S., where FDA said it does not intend to enforce approval requirements for veterinarian-prescribed compounded GS-441524 for specific feline patients with FIP under Guidance for Industry #256. (visualize.jove.com)

Why it matters: For veterinary professionals, ocular FIP remains one of the more challenging presentations because eye and CNS involvement often require higher dosing and careful monitoring for relapse or incomplete response. Recent literature and clinician-facing reviews suggest many ocular signs can improve substantially with antiviral treatment, but outcomes are not universally complete, and the evidence base is still evolving across case series, observational cohorts, and emerging prospective work. Current guidance and expert commentary also reinforce that suspected ocular or neurologic disease often warrants more aggressive dosing than uncomplicated effusive disease, alongside close follow-up of clinical signs and laboratory markers such as serum amyloid A, alpha-1 acid glycoprotein, and the albumin:globulin ratio when available. (pubmed.ncbi.nlm.nih.gov)

What to watch: Expect more discussion this year around optimal dosing, treatment duration, and relapse prevention in ocular and neurologic FIP as newer case series and prospective data move into wider clinical use. A key open question is whether objective stop-treatment criteria and shorter-course protocols can be applied safely to cats with ocular disease, since these cats have often been excluded from simplified treatment studies and are still viewed as higher risk because of blood-ocular and blood-brain barrier penetration issues. (pubmed.ncbi.nlm.nih.gov)