Published by: Ingrid King. Last Updated on: February 7, 2023 by Crystal Uys


Guest post by Ingrid R. Niesman, MS PhD

This is the third installment in a three part series reporting from the 2019 Winn Feline Foundation Symposium on FIP.  Click here to read Part One: The Viral Menace, and Part Two: The Cats and Their Humans Who Fight This Battle.

In the previous posts, we have explored the origins and diagnosis of Feline Infectious Peritonitis (FIP) and the newest research into possible treatments. Given the state of disagreement in clinical test results for a diagnosis and the roadblocks for effective drugs, the best way to stop this disease is to not get it in the first place. Feline enteric coronavirus (FECV) is unfortunately highly infectious and easily transmitted orally between cats.

The proof is in the box

The major point source for infection is the shared litter box. In a multiple cat household, cats share the facilities. Some are avid diggers, others prefer a plop and sniff method. The next guy in the queue is exposed to whatever has been left behind. Virus is shed into feces and can stick to whatever type of litter is filling the box, allowing the virus to stick to paws and get tracked throughout a house.

Short of isolating each cat to a separate box by microchipped doors, there are limited ways to prevent cross contamination between household buddies. So, perhaps a change in the properties of litter can reduce the chance that virus will stick to pieces or better yet, litters could have intrinsic viricidal capabilities.  Dr. Diane Addie, PhD, BVMS, MRCVS at has recently published an extensive study of the properties of specific kitty litter composition and the infectivity of FECV in multi-cat environments.

Her team used two methods to look at the different brands and composition. First, they looked at how much virus stuck to the litter and could still infect cells, a noninvasive approach. From this screen, they determined four kitty litters that stopped the virus from killing cells in culture. To see if these particular formulations could block or lessen viral shedding in realistic multi-cat settings, they used DNA amplification, PCR, to detect infections in cats by collecting swabs. In the end, no litter completely inactivated FECV but litters based on Fuller’s earth (clay litters) proved advantageous in reducing viral shedding over time.

What’s next?

Surely in the future, this study can be the foundation for development of a true anti-viral litter that is safe and cost effective for multi-cat households and shelters, helping to break the cycle of transmission. But until that day arrives, only two other controls can reduce virus transmission. One, development of an effective vaccine and two, find other environmental designs to reduce or eliminate exposure.

 Vaccination as a method to stop transmission

Very little time was devoted to discussing where the science sits in terms of vaccine development during the two day symposium. This is understandable since the audience would be befuddled by a foreign jargon related to antigenicity, molecular structure and binding constants; all principles that are necessary to grasp the complexity of vaccine immunity. With limited incentives to develop an FIPV vaccine, most coronavirus vaccine development is focused on SARS and MERS, but feline medicine can build on the groundwork established by this research. In both cases, vaccines against the conserved Spike protein – the pointy crowns on the outside of the viral particle – have some efficacy, more so with SARS and less so with MERS. As more data emerges from studies of proteins expressed in either the FECV or FIPV phases of disease, more possible immunogens can arise.

The physical state of the vaccine also plays into its effectiveness. Introduction of the promoter of immunity – the antigen – by another virus, usually an adenovirus, is a commonly used method, along with tethering the protein to nanoparticles. Zoetis Inc. markets a modified live virus vaccine against FIPV. Unfortunately, this vaccine is only shown effective in non-infected healthy cats. Ironically, healthy single cat households rarely harbor FECV, so even though these cats may be vaccinated, they are not the major route of cyclic infection.

Taking action to stop this disease from infecting another kitten

Which leaves us with the human touch to help prevent the virus from spreading. Two very unique concepts were introduced in the waning sessions of the symposium.

Twice the size to reduce the stress

The first practical control was presented by Dr. Kate Hurley, DVM, the Director of the UC Davis Koret Shelter Medicine Program. Designed to control feline respiratory infections in crowded shelters, the Low Stress Cat Housing (developed by Hurley’s colleague Dr. Denae Wagner) is also effectively reducing the spread of many feline viruses, including FECV. By separating living rooms from the litter boxes and providing quiet spaces for caged cats, her housing provides a more stress-free space, with enhanced size (8 ft²) over standard 4 ft² cages.


The low stress design includes a sliding portal between the litter and living space, so during cleaning, the cats can be effectively isolated. Therefore, the animals are left untouched by the caretaker, preventing incidental transmission to the next cage. In a study of nine shelters cited by Dr. Hurley, there was a 50-fold reduction in herpes transmission once these units were in place. “We can’t completely eliminate FECV, it’s a roll of the dice. It’s very readily transmitted,” explains Dr. Hurley. “But if feline herpes can be considered a canary in a coal mine, we are off to a good start.”

Cage-free kittenhood

No one really likes to think about cats in cages. What if we prevent kittens from ever being in cages or crowded conditions from the start? Kittens have some protective immunity for FECV early in life from nursing. When people find young litters of kittens, they bring them to shelters out of kindness, which unfortunately then exposes them to the harsh multi-cat environment without the benefits of a mother’s protection.

Our second concept relies on community involvement and action to keep young kittens safe and free from FIPV worries later. The Placer County Animal Shelter has a model program that should spread nationwide. As Katie Ingram, the Animal Services Manager, discussed during the symposium, the shelter contracts with a local fostering group, Kitten Central, to immediately come and take the kittens before they enter the shelter. The County provides all kitten care supplies, medicines and vaccinations to support the foster families. However, they retain “ownership”, relieving the group from adoption worries. At 2lbs, when they are still cutely adoptable, the kittens are returned.

Programs that take vulnerable kittens to sanctuaries rather than cages are the keys for prevention until we can vaccinate, diagnose and treat this dreadful disease. Virus-free means FIP free.

The end of this journey

In these three installments, I have taken you full circle, from infection, diagnosis and treatment to prevention of this fatal disease.

I want to thank the Winn Feline Foundation for hosting this informative meeting.  Seldom does the scientific community get to interact with the constituents most influenced by their solitary work. Although I am not working in this field, I personally gained significant understanding of the biology of the virus, the clinical ramifications and most importantly, the politics of animal medicine.

I have long believed that our investment in animal health is woefully dismal given the meteoric rise of pet ownership and the close bonds we are forming with many different companion animals. If you agree with me, contact your representatives about funding more animal health research through The National Institutes for Health (NIH), United States Department of Agriculture (USDA) or National Science Foundation (NSF).

Ingrid R. Niesman MS PhD is the Director of the SDSU Electron Microscope Imaging Facility at San Diego State University.

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