Feline infectious peritonitis (FIP) is a horrible disease seen most frequently in young cats and kittens. The disease is caused by a corona virus shed in the feces and then ingested. Most cats will develop diarrhea that resolves with time. In 5 to 10% of infected cats, the virus causes severe, usually fatal immune-mediated disease. The virus damages blood vessels which then causes an immune reaction called pyogranulomatous inflammation. If the damage is widespread, the cat develops the wet or effusive form of FIP. Fluid oozes out of the damaged blood vessels and often accumulates in the abdomen. The fluid is straw colored and very sticky. If the damage is confined to one or two organs, the noneffusive or dry form occurs. This form can be very difficult to diagnose and often requires a biopsy to do so.
Treatment of FIP has been focused on decreasing the inflammation causing the vasculitis. Most cats are placed on a steroid called prednisolone or an anti-inflammatory called cyclophosphamide. Although steroids and cyclophosphamide may slow the progression of the disease and make the cat more comfortable, neither will cure the disease. Another treatment involved giving interferon to slow viral replication. This too failed to increase survival time and/or quality of life. More recently, the drug pentoxyfylline was used to decrease the vasculitis caused by the virus and hopefully, lessen the immune response. Unfortunately, a study by Dr. Fischer released in 2011 found no improvement in survival or quality of life.
Since suppressing the immune system hasn’t worked, stimulating the humoral arm of the immune system was tried. The immunostimulating drug, polyprenyl immnostimulant was given to three cats with the dry form of FIP. It was found to prolong their lives and make the cats more comfortable. Maybe we will finally have something to help these poor cats although a trial size of three cats is clearly too small to draw a definitive conclusion.
Sources:
-Fischer, Y et al, “Randomized, placebo controlled study of the effect of propentofylline on survival time and quality of life of cats with feline infectious peritonitis”, J Vet Intern Med. 2011 Nov-Dec;25(6):1270-6.
-Kennedy, M., “Update on Feline Infectious Peritonitis (FIP)”, Vet Med. Aug 2009;104(8):384-392.