Feline Infectious Peritonitis - Diagnosis

Diagnosis

The signs associated with FIP are often non-specific, which can cause diagnosis to be very difficult. There is as yet no definitive diagnostic test for FIP. Diagnosis may include a combination strong clinical suspicion, physical examination findings, presence of abdominal fluid with characteristic chemistry changes and examination of affected tissues for the FIP virus (this is usually performed post-mortem, but can be performed via tissue biopsy). Histopathological examination of tissue samples is usually the cheapest available diagnostic test, but its sensitivity and specificity for FIP is questionable. A polymerase chain reaction test is also available for use with fluid or certain tissue samples; however, its efficacy is currently being reviewed.

More commonly, a presumptive diagnosis is made based on clinical signs and evaluation of abdominal or chest fluid, if available. Fluid caused by FIP tends to be yellow in color and have elevated protein levels. Blood tests can also be performed to bolster a presumptive diagnosis by looking for coronavirus antibodies and elevated protein. Coronavirus titers are NOT considered diagnostic in and of themselves due to the ubiquity of FeCoV, but may be used in conjunction with clinical symptoms to make an FIP diagnosis. It is important to note that cats with higher titres of FCoV are no more likely to develop FIP than those with lower titres.

In the presence of abdominal or chest fluid, a simple test called Rivalta test can be used to differentiate fluid resulting from FIP from fluids resulting from some other disease with very good accuracy.