FIP diagnosis has historically been one of veterinary medicine's greatest challenges, with definitive diagnosis often impossible without invasive sampling and new antigen testing improving access to accurate diagnosis.
FIP diagnosis used to cause significant welfare harm through misdiagnosis-related suffering: cats incorrectly diagnosed with FIP were euthanized when they had other treatable conditions, while cats with confirmed FIP received only palliative care when curative treatment was becoming available. The development of more accessible antigen testing and RT-PCR on effusion fluid, combined with the availability of antiviral treatment, makes accurate diagnosis more important than ever. A cat correctly diagnosed with FIP in 2026 can potentially be cured; incorrect diagnosis is a welfare failure.