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Research on Feline Infectious Peritonitis (FIP) » FAQ

  • Question: What is the dose of Polyprenyl Immunostimulant I need to use for the “dry form” of FIP?
  • Answer: For cats weighing 5 kg or less, the dose is 3 mg/kg, given orally, every other day. For cats above 5 kg, we plateau out on the dose to 7.5 ml, or 15 mg per dose. The concentration is 2 mg/mL. If the volume is difficult to administer, divide the dose in half and give both halves on the same day.
  • Question: You mention that Polyprenyl Immunostimulant helped in cases with dry FIP. My cat has wet FIP. Can I use PI?
  • Answer: We have seen no benefit in the effusive form of FIP but have treated a limited number of cats with the effusive form.
  • Question: My veterinarian prescribed antibiotics to my cat? Is there any contraindication to using PI with antibiotics? With food supplements? Vitamins?
  • Answer: I have not used polyprenyl in conjunction with herbal preparations so I have no experience with that but antibiotics, food supplements and vitamins should be OK.
  • Question: Which percentage of “dry form” FIP cats benefit from PI? What are those benefits?
  • Answer: Our study sponsored by Winn Feline Foundation, found that 22% of cats diagnosed with dry FIP were alive for at least 6 months, and about 5% alive at least a year. The cats on Polyprenyl Immunostimulant that responded generally felt better with a better appetite and were more interactive with the owners.
  • Question: My cat is already receiving treatment with steroids. What do I need to do?
  • Answer: I prefer not having concurrent steroid therapy as an immunosuppressant could interfere with the immunomodulating effect. We prefer to wean them off the steroids if possible. Many of the cats treated with PI have been on steroids and steroids can be given if necessary to maintain appetite and general well being. The prednisolone can be continued until the cat feels better. Weaning off steroids should be done by your veterinarian.
  • Question: What should I expect as adverse effects of PI?
  • Answer: The main adverse effect of Polyprenyl Immunostimulant is that some cats do not like the taste and will foam up when given the treatment. There does not seem to be any other adverse effects noted.
  • Question: How soon will my cat start feeling better?
  • Answer: It seems that the cats that respond to the Polyprenyl Immunostimulant start feeling better in 10-14 days but it may be earlier.
  • Question: What is the mechanism of action of PI?
  • Answer: The aim of PI is to direct the immune response to a cell mediated rather than a humoral, antibody, immune response. The cell mediated response if the only way to destroy the virus in infected cells.
  • Question: How long will my cat need to take Polyprenyl Immunostimulant? Will she be cured after a course of treatment?
  • Answer: I approach dry form FIP as a chronic condition that can be controlled for a while and only occasionally cured. How long to treat before taking cats that are responding well off the Polyprenyl Immunostimulant? I don't know but I would be reluctant to stop the treatment in less than a year.
  • Question: Which form of non-effusive FIP responding to PI, e.g. ocular, neurologic or abdominal?
  • Answer: We have had responses in various presentations of “dry form” FIP. The more advanced the disease, the less likely it is to get a response.
  • Question: Where can we obtain the Polyprenyl Immunostimulant?
  • Answer: Your veterinarian can obtain the polyprenyl from the manufacturer Sass & Sass, Inc. of Oak Ridge, TN. The email address is
  • Question: How can I donate to Dr. Legendre’s FIP research?
  • Answer: You can donate directly to Dr. Legendre’s FIP research at the University of Tennessee through the UTCVM giving site. Visit and follow the blue buttons: TO CVM IT. For the actual giving site listing of gift funds, please add to the printable gift form under Small Animal Clinical Sciences, and below Oncology Research, please list:
    Dr. Legendre for FIP Research

If you connot find an answer to your question please contact Dr. Al Legendre

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