Description
Feline infectious peritonitis (FIP) is a huge diagnostic challenge because of the enormous variety of clinical signs with which the cat can present. In this second of a two-part webinar series the diagnosis of non-effusive FIP will be covered. In my opinion, FCoV antibody testing is recommended in any PUO cat you see, just as you currently routinely screen for FeLV and FIV. In the effusive FIP lecture, we saw that FCoV antibody tests could be falsely negative if used on an effusion rich in virus: this is not a problem in non-effusive FIP, which is the more chronic form of the disease than effusive, with less virus (and fewer lesions). Thus in suspected dry FIP cases we are looking for a FCoV negative antibody test to RULE OUT FIP. However, it is ESSENTIAL to use a test with excellent sensitivity, and some tests have deplorable sensitivity (some tests will be discussed: the best in-house tests are Biogal’s Immunocomb and Virbac’s Speed F-Corona RIM). A FCoV antibody positive result does NOT equate with a diagnosis of FIP, only that FIP remains as a differential diagnosis. Cats who are clinically healthy, but are FCoV seropositive, DO NOT HAVE DRY FIP! Even if the test is called a FIP test: in reality it is a test for FCoV antibody or RNA. Your clinical examination can further rule out or in a diagnosis of dry FIP by a thorough examination of the eyes, searching for evidence of uveitis (e.g aqueous or vitreous flare, iris discolouration, anisocoria, keratic precipitates), or retinal vessel cuffing. Abdominal palpation may reveal enlarged mesenteric lymph nodes and possibly enlarged kidneys (whereas in infectious anaemia - a major differential - palpation will reveal an enlarged spleen). Haematology usually reveals anaemia (Hct/PCR <30%), and, in around a third of cats, lymphopenia. Biochemistry reveals hyperglobulinaemia and often raised bilirubin (as Tsai et al showed, rising bilirubin is a poor prognostic sign). The acute phase protein, alpha-1 acid glycoprotein (AGP) is useful for differentiating FIP from non-infection based similar presenting conditions, e.g. cancer, hyperthyroidism, chronic renal disease, but not from conditions caused by e.g. bacteria.
FIP treatment will not be covered in this lecture, please visit the catvirus.com website for information. It is recommended that you prepare for this lecture by watching the YouTube video called “Does Pancho Have FIP?” which works through the FIP diagnostic algorithm: https://www.youtube.com/watch?v=_JLdLQKpoyA
The lecture contains a spoiler so it really is best to do the video first. Please also have a print out of the latest catvirus algorithm (which Webinarvet will provide): it has been changed slightly since December in light of some recent information.
Diane D. Addie is a veterinary virologist whose PhD and subsequent main focus of research is on the subject of feline infectious peritonitis (FIP). She is former head of diagnostic virology at the University of Glasgow Veterinary School, Veterinary Diagnostic Services, and still acts as consultant there. Now self-employed, she is an independent researcher, holding no shares or directorships in any veterinary or pet food company. She is a member of the European Advisory Board of Cat Disease (ABCD), although ABCD meetings are sponsored by Merial, ABCD members receive no remuneration for their ABCD work and fiercely guard their independence of their sponsors. Diane’s website is www.catvirus.com, it is dedicated to making FIP, feline chronic gingivostomatitis and other difficult to source information freely available to veterinarians and to educate the public. Her YouTube channel is Dr Diane D Addie and she can be found on Facebook as Diane Addie (the cat virus logo is the photo) and followed on Twitter @FIPvet. She is author of many papers published in refereed journals; veterinary textbook chapters and the book for cat guardians ‘Feline Infectious Peritonitis and Coronavirus’ available from Amazon or catvirus.com.