Differential Diagnosis

Feline Infectious Peritonitis is a diagnosis of exclusion, and often misdiagnosed.
Check out what other diseases can be mistaken for FIP.

Differential Diagnosis table

If your cat has been diagnosed with FIP, your first step is to ensure you have the correct diagnosis. Why? Because errors are frequent. Getting a wrong diagnosis can be more devastating than no diagnosis at all. It is estimated that 70 to 80% of cats diagnosed with non-effusive FIP turn out to have another condition, usually treatable. The likelihood of error in the case of effusive (wet) FIP is lower but still varies widely depending on the cat's age and breed. Making sure you have the correct diagnosis means talking to your vet. The number one source of WRONG diagnosis is a positive FCoV titer. 95% of cats are FCoV (Feline Coronavirus) carriers at one point or another. It does not mean they will develop FIP. Only 5% of them end up developing Feline Infectious Peritonitis. Also, be aware that there is NO DEFINITIVE TEST for FIP. So, if you are told your cat tested positive for FIP, chances are he or she tested positive for exposure to coronavirus. Positive FCoV titer DOES NOT MEAN your cat has FIP. FIP is a difficult diagnosis to reach, and is a process of exclusion, particularly with the dry (non-effusive) form.

downloadDownload our table of differential diagnoses for both the dry and wet forms of FIP.
This list is non-exhaustive. Please discuss these options with your veterinarian.

Complete body fluids differential diagnosis table

The accumulation of fluid (or ascites) in the chest or abdominal cavities is characteristic of the effusive form of Feline Infectious Peritonitis. However, there are more than one type, and one reason for the presence of fluid in a cat's body. The complete body fluids diagnosis table by Dr. Salih Sahir is one of the most detailed and thorough documents available. We recommend you print this useful table and take it to your veterinarian if your cat has been diagnosed with wet FIP based on the presence of fluid, but the fluid has not been examined and tested.

downloadDownload Dr. Sahir Body Fluids Differentials Diagnosis Table for a complete list of body fluids type, their causes, and conditions.