Predictors of Short-Term Mortality in Cats With FIP Receiving Antiviral Therapy

In the Literature

Goto S, Kamiyoshi T, Iwasaki R. Predictive factors associated with short-term mortality in cats with feline infectious peritonitis treated with remdesivir or GS-441524 or both. J Vet Intern Med. 2025;39(1):e17249. doi:10.1111/jvim.17249

The Research …

Treatment of FIP has been revolutionized by GS-441524, remdesivir, molnupiravir, and other antivirals¹; however, questions regarding drug selection, predictive factors for mortality, therapy length, dosage, and adjunct therapies remain.

This retrospective study of 108 cats with FIP was designed to identify predictive factors for short-term mortality following treatment with intravenous remdesivir, oral GS-441524, or both. Patient signalment, clinical signs, abdominal ultrasonography findings, clinicopathologic variables, and either date of death within 84 days of treatment initiation (ie, short-term mortality) or date of last follow-up were examined. Cats were objectively classified as severely affected (ie, obtunded, moribund) or less severely affected (ie, bright/quiet, alert, responsive).

Thirteen cats (12%) died after treatment was initiated, most within 1 week. Of cats that survived, most received a standard 84-day treatment course. Some cats received adjustments (eg, general extension, dose escalation) based on response to therapy. Relapses were observed in 2 cats after treatment completion; retreatment was successful.

Cats classified as severely affected had a higher mortality rate than cats classified as less severely affected.² Cats presented with respiratory distress or pyrexia also had an increased mortality rate. Corticosteroid administration was more common in cats that died and cats that were severely affected and was likely a confounding variable. Cats that died were more likely to have lower body temperature, higher bilirubin, lower albumin and total protein, and lower sodium and potassium levels; however, in multivariate analysis, only elevated lactate dehydrogenase (LDH) was a significant predictor of nonsurvival. Plasma LDH activity ≥323 U/L had a sensitivity of 83.3% and a specificity of 89.6% for predicting death. Serum amyloid A levels were not predictive of survival, despite increasing use of acute-phase proteins for monitoring of cats with FIP.³

… The Takeaways

Key pearls to put into practice:

• This study provides insight into the prognosis of cats with FIP. Although some results (eg, lower survival in more severely affected patients) may appear intuitive, evidence-based confirmation is beneficial. Extending this research via prospective studies or investigation of other treatments (eg, molnupiravir⁴) and cotreatments may be of interest.

• Survival was reduced in cats with elevated LDH. Measuring LDH in cats diagnosed with FIP may be worthwhile, but LDH is not always a routine assay in small animal medicine. Higher doses of medication, more aggressive supportive care, and a more guarded prognosis may be warranted in cats with elevated LDH.

• Prognosis for cats with FIP is still not completely positive. Pet owners should be counseled that more severe disease is associated with a worse prognosis. Although this study identified elevated LDH as a negative prognostic indicator, a single value should not be the basis for a euthanasia decision and should be assessed in conjunction with clinical status, quality of life, and owner finances and beliefs.