We’re all familiar with coronaviruses; COVID-19 in particular. There is also a type of coronavirus that only affects cats, known as FCoV. Worryingly, a new viral strain (FCoV-23) has been identified as the cause of a recent deadly outbreak affecting cats in Cyprus. It’s now been detected in the UK, brought over by an imported cat. 

How concerning is this new strain of virus, and what risk does it pose?

Table of contents

What is FCoV-23?

First, it’s important to state that this virus does NOT threaten humans and is not related to COVID-19. 

FCoV is found worldwide and will affect almost every cat. It usually causes little to no signs of infection and the virus is easily destroyed by most household disinfectants and detergents.

The trouble starts when, given the right conditions, the virus mutates (changes) inside the cat to cause Feline Infectious Peritonitis (FIP). This is a disease that can be fatal and until recently, had no reliable cure. It’s estimated that only 0.3-12% of cats will go on to develop FIP after exposure to FCoV. This number is variable, depending on certain risk factors such as the presence of overcrowding and poor hygiene, but most pet cats are at low risk. Fortunately, cats that develop FIP aren’t infectious to other cats. 

That is, until FCoV-23 came along

A recent study has found that this mutant coronavirus appears to cause a highly transmissible variant of FIP in cats.

It’s thought the new strain is a product of the blending together of both dog and cat varieties of coronavirus. Sound familiar? Coronaviruses have an innate ability to recombine with other coronaviruses, and this potential for cross-species transmission poses a serious threat to both animal and human health.

What has been happening in Cyprus?

The outbreak was first identified in the capital Nicosia in January 2023. The following eight months saw a 40-fold increase in FIP cases compared to the previous two years, with 165 cases identified. 

FIP usually affects young cats, but this outbreak showed no age discrimination. And it’s not just street cats that have been falling ill; even indoor cats have developed the disease.

Genetic sequencing of the virus was carried out. It appeared to have originated from recombination of both cat and dog coronaviruses. Researchers dubbed this new strain ‘FCoV-23’. 

Infection with FCoV-23 is more likely to lead to the development of FIP in cats because it seems to cause the illness without needing to mutate within the infected cat. It also appears that the cats who developed FIP are spreading the disease, which is a concerning change. 

It’s still early days yet, but this virus is not thought to affect dogs.

What is the current risk to UK cats?

In November 2023, it was reported that a cat imported to the UK from Cyprus back in August had subsequently developed FIP. Testing revealed that the cat had been infected with FCoV-23. The cat in question was identified early and was quickly confined indoors, but vets in the UK have been advised to be on the lookout for any further cases, particularly where there has been a recent history of overseas travel.

Can anything be done to limit the spread of this disease?

Limiting the international movement of cats will be key to preventing this local outbreak from becoming a global problem. If more cases are detected in the UK, it is likely they will stem from imported cats that have not been screened before entry. Overcrowded, stressed cats are at the highest risk for developing FIP, so densely stocked cat rescue facilities (especially those taking in cats from overseas) may well be ground-zero for a UK outbreak. 

Vets and owners are advised to stay vigilant. Early detection will allow time for the virus to be contained. Some of the early signs of FIP to look out for include:

  • Listlessness
  • Reduced appetite
  • Weight loss
  • Fever

Later, the disease progresses to cause other signs such as a swollen belly, difficulty breathing, wobbly walking, collapse or seizures. You can learn more about the signs of FIP here. 

Treatment

Treatment (with remdesivir and GS-44152) is available on the Cascade but is unlicenced and costly. If you haven’t got your cat insured already, this is another reason to seriously consider it now. If FCoV-23 began to spread through the unowned cat population, the use of this treatment would be seriously limited by cost. Euthanasia on welfare grounds would be the kindest alternative.

Most disinfectants and detergents will destroy the virus so good hygiene, especially of litter trays, is recommended. The risk is highest in multi-cat households, breeding catteries and cat rescue facilities, where attention to hygiene and disinfection is essential. Stress plays a role in the development of FIP, and you can read more about reducing stress in cats here. 

In conclusion

Further investigations into the properties of FCoV-23 are needed. For example, it is currently unknown how long cats infected with FCoV-23 will remain infectious. Ultimately, if this new variant of FIP becomes more prevalent, the development of an effective vaccine would be the next logical step in tackling the virus. Let’s hope that it’s something pharmaceutical researchers are looking into, as the existing vaccines are very limited.

Further reading