Feline infectious peritonitis (FIP) is a coronavirus disease that affects domestic and wild cats worldwide. The disease results in accumulation of fluid and inflammation within body cavities, particularly the abdomen. Until recently, no effective treatments had been identified, with death rates approaching 100%. In 2019, researchers showed successful use of a drug called GS-441524 to treat naturally occurring FIP. With the subsequent emergence of the COVID-19 global pandemic, access to coronavirus anti-viral drugs was prioritized for human investigation. Remdesivir (GS-5734) is metabolized into GS-441524 and initially held promise for treatment of human COVID-19 patients. As such, governments pushed to rapidly license this drug and stockpile it in human hospitals. Subsequent research using remdesivir in human COVID patients has shown no improvement in survival times or outcomes, leading to the World Health Organisation recommending against its use. Meanwhile, anecdotal reports have been arising of remdesivir proving efficacious in the treatment of FIP in cats. Treatment trials will soon commence using remdesivir in cases of naturally occurring FIP in Australia. This study will examine the way remdesivir is metabolized by cats; its safety profile in cats with naturally occurring FIP; and ultimately what is the effective dose-rate for treatment of FIP in cats.