Because FIPV is an immune-mediated disease, treatment falls into two categories: direct action against the virus itself and modulation of the immune response.
Until recently, FIPV was considered to be a non-treatable disease. While there are still some uncertainties regarding the long-term effectiveness of recently-identified antiviral drugs to treat FIP, studies in both the laboratory and in client-owned cats with naturally occurring FIP suggest that a drug currently referred to as 441 may ultimately prove to be an effective treatment option for (minimally) the effusive form of FIP. While some cases of the non-effusive form of FIP responded to 441 therapy in these trials, the responses in cases with this form of FIP were not as favorable as those seen in cases of the effusive form. This drug is currently not FDA-approved, however, and while there are a number of sources offering it for sale, anecdotal reports suggest that the products being provided by some of these sources vary widely in both accuracy of reported drug concentration and purity. It is very important to discuss the risks, benefits, and evolving acquisition and regulatory issues with your veterinarian if you are considering therapy with 441. Supportive care, including fluid therapy, drainage of accumulated fluids, and blood transfusions, is also indicated in some cases.