Scientists identify feline Long COVID model that could help inform human treatments
Researchers believe a deadly cat coronavirus disease called feline infectious peritonitis may mirror Long COVID in humans.
- 21 July 2025
- 3 min read
- by Linda Geddes
Humans aren’t the only ones afflicted by persistent problems after catching a coronavirus. Cats, too, can also suffer from ongoing immune system dysfunction after contracting feline infectious peritonitis (FIP) – a condition that may represent a cat equivalent of Long COVID, researchers say.
By studying the disease, they hope to bridge key gaps in understanding how the human immune system malfunctions after viral infections like COVID-19 – and to uncover promising treatments. A small study has already identified a potential cell-based therapy that may help cats to recover, which is also being explored in human patients with Long COVID.
“It’s important to understand that many pets suffer from diseases that are similar to human diseases,” said Dr Amir Kol, an associate professor at the UC Davis School of Veterinary Medicine in California, US, who led the research.
“Our findings support the idea that FIP in cats is a useful model for studying long-term immune problems after a viral infection – something that also happens in some people after illnesses like COVID-19.”
Cat coronavirus
Feline infectious peritonitis is caused by a coronavirus called FIP virus, which usually infects intestinal cells, causing mild and short-lived stomach issues. However, in some cats, a mixture of genetic and environmental factors can alter the behaviour of the virus, enabling it to infect immune cells and spread throughout the body. When this happens, it triggers fever, widespread inflammation, organ damage and diminished levels of white blood cells.
Until recently, such infections were also frequently deadly – but an antiviral agent called GS-441524 is now available that can provide a cure. However, even after cats recover, their immune systems often remain activated – much like the prolonged immune responses seen in human patients with Long COVID, which have been linked to symptoms such as fatigue, brain fog and heart palpitations.
Kol and colleagues wondered if a treatment known as mesenchymal stromal cell (MSC) therapy – which involves transplanting MSCs from healthy individuals into those who are suffering from disease – might help. MSCs are found in many different tissues and can differentiate into various cell types; they also interact with and regulate the behaviour of immune cells. Because of this, they are being investigated as a treatment for various autoimmune and inflammatory diseases, including Long COVID and COVID-related lung damage.
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Combination therapy
In the current study, 11 cats with FIP were either given antiviral drugs along with infusions of MSCs, or the antiviral drug plus placebo infusions.
The research, published in Stem Cells Translational Medicine, suggested that the cell infusions reduced systemic inflammation and helped the cats’ immune systems to recover. MSC-treated animals had fewer overly active T and B cells and higher numbers of regulatory T cells, which help to calm the immune system. “We definitely saw evidence of immune recovery in those cats that were treated with MSC compared to the ones that weren’t,” said Kol.
Although this was only a small study and the cats weren’t critically ill, “It shows that MSC therapy might not only reduce short-term inflammation but help bring the immune system back into lasting balance.”
Further research is clearly needed. However, Kol believes these findings may not only matter for helping cats with FIP, but could also advance our understanding of similar post-viral conditions in humans, like Long COVID.
“Veterinary medicine is a wonderful platform to conduct translational science that helps both pets and humans,” he said.
