Antiviral Molnupiravir Shows Effectiveness in Treating FIP in Cats

Lisa Selvaggio
by Lisa Selvaggio

Feline infectious peritonitis (FIP) is a devastating disease that was always fatal in the past until medical breakthroughs allowed for treatment options. A well-known medicine is GS-441524, but there’s another medication that veterinarians can consider, particularly for cats who don’t respond to GS-441524, and it’s known as molnupiravir. Keep reading to learn about this antiviral and its potential in treating FIP.  

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Research from Colorado State University


After testing molnupiravir, veterinarians at Colorado State University found that this antiviral is 77% effective against FIP in cats, supporting other research that has also noted its effectiveness.  


To see if the medication would work, a clinical trial took place at CSU’s Veterinary Hospital. A total of 73 cats with naturally occurring FIP participated in the study with their owners’ consent. Treatment was given orally twice daily for 12 weeks. The cats also had checkups regularly for a total of six months.


77% of the cats in the study survived, with 12% of them relapsing but surviving after undergoing another round of treatment.


Side effects included constipation, diarrhea, hypersalivation, nausea, vomiting, reduced appetite, pruritus, folded ears, elevated ALT, and neutropenia. But none of the cats had side effects that would’ve required them to stop receiving the medicine.  


There Are Now Two Good Treatment Options for FIP


GS-441524 is roughly 80% effective, so it may still be the main drug that vets turn to for FIP, but this research shows that molnupiravir can also be used as a treatment against the disease. This means veterinarians can treat cats who fail to respond to GS, who stop responding to it, or who relapse. And, like GS, veterinarians can prescribe molnupiravir from a compounding pharmacy.  


More research is being conducted to see if other treatments, such as Paxlovid, might be effective as well. Also, because FIP, which is caused by feline coronavirus, is much like severe coronavirus in people, experts want to figure out if FIP survivors experience symptoms like those caused by long COVID. The research they’re doing on FIP in cats might help them uncover important insights that can help humans, too.     


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Lisa Selvaggio
Lisa Selvaggio

Lisa Selvaggio is a freelance writer and editor, and our resident cats-pert, with certifications in pet nutrition and pet first aid. She enjoys producing content that helps people understand animals better so they can give their pets a safe and happy home.

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