Reader Question: LTCI vs. IM, Two New FIP Treatments
Written by Steve Dale   

Q: You’ve written that for kittens with FIP (feline infectious peritonitis) there are two experimental drugs, PI and LTCI. Which is a better choice? S. J., Cyberspace

A: Unfortunately, no one knows the answer to your question. Taking one step back, FIP is a fatal disease which most often affects kittens (though any cat of any age might potentially get this disease). The good news is that there seems to be a renewed flurry of interest from veterinary researchers attempting to sock FIP.

Dr. Al Legendre, professor department of small animal clinical sciences at the University of Tennessee College of Veterinary Medicine, Knoxville, is working on how one drug, Polyprenyl Immunostimulant seems to be helping some cats with FIP. This drug is the PI you referred to in your question.

LTCI or Lymphocyte T-Cell Immune Modulator, is an immune regulating drug. LTCI has offered some promise by apparently helping a very small number of kittens with FIP. “As far as I know, there’s been – so far – no peer reviewed publication on LTCI,” Legendre says. 

Another drug to fight FIP, feline omega interferon recently showed enormous promise based on an initial Japanese study. However, subsequent studies have not been able to reproduce a positive response. There’s always been buzz about humane omega interferon, but no data, as far as Legendre knows, has ever been encouraging.

Legendary veterinary researcher Dr. Niels Pedersen, director for the Center of Companion Animal Health at the University of California School of Veterinary Medicine, Davis recently noted the number of kittens who die from FIP is higher than previously thought. Pedersen is focusing his work on a genetic explanation for susceptibility.

“As for choice of treatment, sadly there is none, at least not yet,” says Legendre. “I’m biased because I am working on PI, and the drug does seem to help some cats, with the dry form of the disease. (There’s a dry and a wet form of FIP). I can’t say PI is a magical answer, but I can say some of what we’re witnessing is promising. For FIP, the disease is so complex and so aggressive, the ultimate answer may be just as complex.”

If you have a kitten diagnosed with FIP, Legendre will attempt to make the drug available, but do understand PI is still considered experimental. Your veterinarian can contact Legendre at This e-mail address is being protected from spambots. You need JavaScript enabled to view it .