NEUROLOGICAL AND/OR OCULAR FIP

     The neurological and/or ocular forms of FIP can be confused with feline systemic toxoplasmosis, which is why so many cats with these forms of FIP are tested for toxoplasmosis and treated with Clindamycin or other antibiotics. However, systemic toxoplasmosis is an exceedingly rare disease of cats, especially when compared to FIP. FIP can be easily differentiated by origin (cattery, foster/rescue, shelter), signalment (age, gender, breed), and basic blood test results. Deep fungal infections (coccidioidomycosis, blastomycosis, histoplasmosis) can cause similar clinical signs to dry FIP but are still uncommon even in their endemic regions. Lymphoma may also be a differential diagnosis for dry FIP, but this disease is usually sporadic and in older cats. The diagnosis of neurological and/or ocular disease is ultimately based on where a cat comes from, the clinical signs, age, common changes in complete blood count (anemia, lymphopenia), serum protein changes (high total protein, high globulin, low albumin, low A:G ratio). The diagnosis may be confirmed if there is still doubt, by characteristic changes in cerebrospinal fluid (CSF) and aqueous humor (high protein, high cells, neutrophils, lymphocytes, macrophages), suggestive lesions on MRI, PCR or immunohistochemistry on CSF, or high serum coronavirus antibody titer by IFA (>1:3200). One must be careful, however, to follow the 70% rule, i.e., no single typical laboratory abnormality will occur 100% of the time.