Until recently, FIP was considered to be a non-treatable and almost routinely fatal disease. While there are still some uncertainties regarding recently-identified antiviral drugs to treat FIP (including their long term effectiveness, ideal minimum dose, potential for the development of drug resistance, and best drug mechanism of action to recommend/pursue), studies in both the laboratory and in client-owned cats with naturally occurring FIP suggest that the drug that has been most extensively studied, referred to as GS-441524, is a safe and effective treatment option for cats diagnosed with of FIP. This drug has been available in Australia and the UK for several years, and has only recently become available as an orally compounded formulation in the US. Prior to this recent US GS-441524 release (and continuing through today), a number of “black market” sources have been offering GS-441524 for sale. Importantly, some reports suggest that the products being provided by some of these sources vary widely in both accuracy of reported drug concentration and purity, making this recent release of a reliably produced oral formulation in the US that much more impactful.  It is very important to discuss the risks and benefits of GS-441524  with your veterinarian if you are considering pursuing therapy with this game-changing drug in a cat suffering from FIP, and a veterinary prescription is required to obtain it. Supportive care, including fluid therapy, drainage of accumulated fluids, and blood transfusions, is also indicated in some cases.