Retrospective study and outcome of 307 cats with feline infectious peritonitis treated with legally sourced veterinary compounded preparations of remdesivir and GS-441524 (2020-2022)

Abstract

Objectives: Feline infectious peritonitis (FIP) is a serious disease that arises due to feline coronavirus infection. The nucleoside analogues remdesivir and GS-441524 can be effective in its treatment, but most studies have used unregulated products of unknown composition. The aim of the present study was to describe the treatment of FIP using legally sourced veterinary-prescribed regulated veterinary compounded products containing known amounts of remdesivir (injectable) or GS-441524 (oral tablets).

Methods: Cats were recruited via email advice services, product sales contacts and study publicity. Cats were excluded if they were deemed unlikely to have FIP, were not treated exclusively with the veterinary compounded products, or if there was a lack of cat and/or treatment (including response) data. Extensive cat and treatment data were collected.

Results: Among the 307 cats recruited, the predominant type of FIP was most commonly abdominal effusive (49.5%) and then neurological (14.3%). Three treatment protocols were used; remdesivir alone (33.9%), remdesivir followed by GS-441524 (55.7%) and GS-441524 alone (10.4%). The median (range) initial treatment period duration and longest follow-up time point after starting treatment were 84 (1-330) days and 248 (1-814) days, respectively. The most common side effect was injection pain (in 47.8% of those given subcutaneous remdesivir). Of the 307 cats, 33 (10.8%) relapsed, 15 (45.5%) during and 18 (54.5%) after the initial treatment period. At the longest follow-up time point after completion of the initial treatment period, 84.4% of cats were alive. The cats achieving a complete response within 30 days of starting treatment were significantly more likely to be alive at the end of the initial treatment period than those cats that did not.

Conclusions and relevance: Legally sourced remdesivir and GS-441524 products, either alone or used sequentially, were very effective in the treatment of FIP in this group of cats. Variable protocols precluded statistical comparison of treatment regimens.

Keywords: Survival; antiviral; coronavirus; nucleoside analogue.

Figure 1

Pie chart illustrating the number and percentage of each type of predominant feline infectious peritonitis among the 307 cats in the study

Figure 2

Boxplot showing starting doses of remdesivir and GS-441524 as sole treatment and in the combination group treated with remdesivir and GS-441524 sequentially. The boxes are edged by the 25th and 75th percentiles of the data, with the median (50th percentile) shown by a line within the box. The crosses indicate the mean of the data. The whiskers mark the 5th and 95th percentiles and values beyond these upper and lower bounds are considered outliers, marked with coloured dots

Figure 3

Bar chart showing the percentage of the 307 treated cats that were alive at the longest follow-up time point after starting treatment and also showed a complete response to the nucleoside analogue treatment indicated

Figure 4

Boxplot showing time to normalisation in days of various clinical and clinicopathological parameters during treatment for feline infectious peritonitis. HCT = haematocrit; AG = albumin to globulin ratio. The blue boxes are edged by the 25th and 75th percentiles of the data, with the median (50th percentile) shown by a line within the box. The crosses indicate the mean of the data. The whiskers mark the 5th and 95th percentiles and values beyond these upper and lower bounds are considered outliers, marked with blue dots. HCT boxplots represent HCT or packed cell volume, depending on which was reported in the haematology profiles

Figure 5

Bar chart showing the percentage of the 307 treated cats showing the most common adverse effects seen during injectable remdesivir and/or oral GS-441524 treatment. GS-441524 is an oral medication and so pain on injection relates to injectable remdesivir administration only. Figures within bars are the percentage of cats affected. ALT = alanine transaminase