Covid drug effective in treating FIP, study finds
Without treatment, many cats with FIP quickly deteriorate.
An anti-viral drug used to treat humans with Covid-19 has proved highly effective in treating cats with feline infectious peritonitis (FIP).
Remdesivir, which was made available to prescribe by veterinary surgeons in 2021, could now form part of a tailored treatment plan, shortening the length of FIP treatment.
FIP is caused by a mutated feline coronavirus. The disease can cause a build-up of fluid, extreme muscle and weight loss, and can ultimately result in organ failure.
Without a proper treatment plan, many cats with FIP will deteriorate with little chance of survival.
Researchers from the Royal (Dick) School of Veterinary Studies assessed data from its Hospital for Small Animals, which frequently treats cats with FIP. While using a treatment plan including Remdesivir, the hospital reported a survival rate of over 85 per cent among its patients.
One of the first cats to be treated with with the drug was Rebus, a ten-year-old domestic short-haired cat.
Rebus was referred to the the hospital's Feline Service after showing rapid weight and muscle loss. He was not eating, was lethargic, and was drinking and urinating excessively.
An examination revealed that he was critically anaemic, had enlarged lymph nodes and recorded a high white blood cell count. He required fluids and pain relief and the nursing team had to help him eat.
A needle biopsy of Rebus' lymph notes confirmed the illness was FIP. He was also found to be suffering from kidney damage.
Rebus originally received injections of Remdesivir, before being moved on to its active ingredient, GS-441524.
Within three months, he made a full recovery from FIP. Three years later, Rebus continues to live an active life and is receiving ongoing care for chronic kidney disease.
Although usually harmless in the gut, feline FIP can become dangerous if it mutates and migrates into immune cells. An estimated 40-50 per cent of cats carry the virus, reaching 80-100 per cent of cats in a multi-cat household.
Clinicians are now developing a patient-centred treatment plan designed to reduce drug resistance and make treatment easier.
Conor O'Halloran, resident in internal medicine, said: “I remember when FIP was a death sentence. The advent of these medications to be able to provide safe and legal treatment has been revolutionary for us as cat-loving vets.”
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The BSAVA has opened submissions for the BSAVA Clinical Research Abstracts 2026.
