Feline infectious peritonitis (FIP) is perhaps the most devastating infectious disease of cats and there remains a desperate need for a fast and reliable diagnostic test. FIP is caused by the Feline Infectious Peritonitis Virus (FIPV), which has undergone subtle mutations from its normal gastrointestinal counterpart, Feline Enteric Coronavirus (FECV). Clinical signs in the cat are vague and nonspecific, and can include inappetence, lethargy, disorientation, vomiting and diarrhea. Unfortunately, a definitive diagnosis of FIP is often challenging and is typically a diagnosis of exclusion, which is frustrating for owners and veterinarians, alike. While several assays capable of confirming FIP have been developed, these tests can require invasive methods and lengthy wait times for results. We have employed a powerful new technology to simultaneously measure more that 1300 proteins in the blood of cats with FIPV. We compared these results to normal cats and cats infected with other viruses to identify unique proteins that might allow diagnosis of FIPV. We then evaluated a total of 56 cats and utilized statistical modelling to reduce the number of candidate proteins from >1300 to 18. Our current plan is to further evaluate these 18 proteins for accuracy with feline samples prior to ultimately validating a diagnostic test for FIPV.