Ocular FIP treatment comes into sharper clinical focus

CURRENT BRIEF VERSION: FIP treatment is moving into a more practical, evidence-based phase for cats with ocular disease. A 2024 observational case series of 20 cats with ocular involvement found that most were treated with remdesivir, GS-441524, or both for 84 days, with clinicians commonly using higher doses in the 15 to 20 mg/kg range because ocular disease appears to need stronger drug exposure than uncomplicated effusive cases. In that study, 17 of 20 cats transitioned to oral GS-441524, and prior reports cited by the authors showed full recovery in 4 of 5 cats with combined ocular and neurologic disease treated at higher doses. VetGirl’s clinical review adds useful context: ocular signs are more common in non-effusive FIP than wet FIP, can occasionally be the dominant presenting feature, and may include anterior uveitis, keratic precipitates, iris color change, dyscoria, hyphema, hypopyon, fibrinous exudate, retinal lesions, hemorrhage, vascular tortuosity, or detachment. The broader shift is that these protocols are no longer just theoretical or informal: compounded oral GS-441524 became legally prescribable in the U.S. on June 1, 2024, under FDA enforcement discretion, giving veterinarians a regulated pathway for treatment that used to depend heavily on black-market sourcing. (pmc.ncbi.nlm.nih.gov)

Why it matters: For veterinary professionals, ocular FIP is increasingly looking less like an outlier and more like a dosing and monitoring challenge. Current guidance from ABCD and clinical summaries now consistently note that ocular and neurologic FIP often require higher doses than cats with effusions alone, likely because antivirals must penetrate the blood-ocular and blood-brain barriers. That has practical implications for case triage, client counseling, cost discussions, and follow-up, especially as oral GS-441524 becomes easier to prescribe in the U.S. It also gives clinicians a safer alternative to inconsistent internet products; one 2024 study found unlicensed at-home antivirals contained GS-441524 in amounts that differed significantly from what was advertised. Broader FIP discussions are also starting to focus on how treatment is monitored and when it can safely stop, with acute phase proteins such as serum amyloid A and alpha-1 acid glycoprotein, along with the albumin:globulin ratio, being explored as more objective markers than clinical improvement alone. (abcdcatsvets.org)

What to watch: Expect more refinement around ocular-specific dosing, adjunct anti-inflammatory use, and whether shorter or individualized treatment courses can match the traditional 84-day protocol, especially if higher-dose induction strategies and biomarker-guided stopping criteria hold up in larger studies. (pmc.ncbi.nlm.nih.gov)