April 14th, 2023
Wet (or Effusive) FIP
Dr Diane Addie is a leading expert in the world of feline medicine and you couldn’t have asked for anyone better to lead a webinar on effusive FIP, and thanks to ‘The Webinar Vet’ this was delivered to its members as a pre-Christmas treat. As you can imagine it went down just as well as the numerous mince pies consumed over the festive period, although I am fully aware this FIP webinar was by far the healthier option and significantly better for me.
A revision and update covering feline effusive FIP can only be of benefit especially as, according to the participating audience, vets seem to encounter these cases relatively infrequently, meaning this condition is perhaps less familiar than more common feline ailments. Dr Addie also reported 80% of FIP cases referred to herself turn out eventually not to have FIP indicating that there are a lot of pitfalls associated with diagnosing FIP correctly.
To aid with diagnosis Dr Addie cited a diagnostic FIP algorithm available on her website, www.catvirus.com. This algorithm asks a number of questions regarding history, clinical examination and the results of tests performed on effusions. Dr Addie took us through the steps of this algorithm citing the case of Oliver, a nine month old MN Persian. Oliver presented with weight loss, anorexia and lethargy and after a number of diagnostic tests was found to have a thoracic effusion. The audience was asked if, at this stage, they would perform a Coronavirus virus titre test. Of course a positive Coronavirus titre test does not mean that Oliver has FIP and indeed a significant proportion of cats will be seropositive. However, Dr Addie still advised performing this test because if negative, FIP can definitively be ruled out from the list of differentials. In this case Oliver tested seropositive for Feline Coronavirus.
Dr Addie explained the most useful diagnostics performed to diagnose FIP are the tests carried out on a cat’s effusions. Effusions in cases of FIP are expected to be clear, straw coloured, frothy (due to high protein levels) with no unpleasant odour. Dr Addie advocated the use of the Rivalta test in practice which can be performed very simply in house at the cost of pennies. The test is demonstrated on YouTube and involves placing a few drops of white vinegar into 10mls of water. Two to three drops of the effusion is then placed into this suspension and a positive outcome is indicated if the effusion looks somewhat like a jelly fish. If positive there is a 58.4% chance that the affected cat has FIP. However, when the outcome is negative, there is a 93.4% chance that the affected cat does not have FIP, making it an excellent ‘rule out’ test.
Other tests were discussed including performing a Feline Coronavirus PCR test on effusions which, if positive, confirm a diagnosis of FIP. However if negative, FIP cannot be completely excluded. The number of steps which need to be taken and the number of tests available to aid in the diagnosis of FIP indicates the complexity of this condition, and this webinar has been invaluable in reminding and updating vets on those very necessary steps as well as highlighting the all-important algorithm on Dr Addie’s website. Unfortunately it was not good news for Oliver who was eventually confirmed as having FIP. He did, however, go on to survive a further 18 months with the use of steroids and interferons, demonstrating how some of these cases can continue to have a good quality of life for a reasonable amount of time.