What is Feline coronavirus (FCoV)?
Feline coronavirus (FCoV) infection is a common viral infection in cats. Most cats are subclinically affected, but up to 10% develop Feline Infectious Peritonitis (FIP). Infected cats mount an immune response with detectable antibody levels that decline or may disappear if the cat recovers.
Where is FCoV found?
The natural habitat of FCoV is the intestinal cells lining the small and large intestines and monocytes/macrophages.
How is FCoV transmitted?
FCoV is Shed in the faeces and occasionally the saliva. Directly, it can be transmitted by cat-to-cat contact, e.g. nose to nose, mutual grooming and contaminated coat. Indirectly, especially using shared litter trays, but also via contaminated fomites. Transmission is extremely rare during birth to kittens.
What are the effects of FCoV?
Multiplication in intestinal epithelial cells and within the nostrils leads to: -
Mild intestinal and respiratory signs.
Shedding of FCoV in faeces from 2 days that may continue for several
Intestinal cells (macrophages) uptake of FCoV leads to regional lymph nodes being colonized, causing the virus to spread through blood (monocyte associated viremia).
In most cats, mucosal immunity (IgA) and possibly cell-mediated immunity develops, and infection ceases, but a small number of cats may become long-term carriers.
Some cats exhibit serious diarrhoea which may be unmanageably lasting for months. Some have diarrhoea and third eyelid syndrome.
Effectiveness of cat's immunity correlates with disease: good immunity leads to clearance of the virus by the cat while a poor immunity leads to disease.
In a small number of cats (<10%) FCoV changes within the intestinal cells (macrophages/monocytes) causing replication interfering with the immune system causing inflammation of blood vessels (vasculitis/granuloma formation) reducing the albumin:globulin ratio to <0.6.
The mutations produce a virus capable of causing FIP.
Most cats with FIP have one of these mutations in FCoV from affected tissues.
Cats without FIP do not have these mutations in FCoV found in their faeces.
How is FCoV Controlled?
Control using chemotherapies
Currently, there is no known treatment to stop FCoV from being shed by carrier or briefly infected cats.
Cats with FCoV-associated diarrhoea are treated symptomatically.
For the treatment of cats with FIP see Feline infectious peritonitis.
Control through environmental control
Control of FCoV infection is based on reducing environmental viral levels by reducing factors that increase the viral load and shedding by individuals, and clearing of the virus from the environment through the following:
Cutting the number of cats kept in any small area.
Preventing the introduction of FCoV-infected cats to immature cats.
Preventing the introduction of FCoV to uninfected cats via contaminated bowls, litter trays, cages, etc.
Good hygiene as faeces is a major source of the virus, remove faeces from litter trays as soon as possible after use and regularly disinfect trays using sodium hypochlorite.
Keeping cats in good health.
Reducing stress on cats.
For control of FCoV under specific circumstances (e.g. breeding cattery) see Feline infectious peritonitis.
Control through Vaccination
A vaccine is available in some parts of the world, but it is not recommended by consensus panels Feline Specialists.
The vaccine is temperature-sensitive
It is administered intra-nasally.
The vaccine has efficacy of approx—50-75% as a preventable fraction.
The vaccines don’t prevent disease after exposure to FCoV.
The vaccine, where licensed, is administered at >16 weeks of age at which time many kittens have already been infected.
References
Tasker, S. (2018). Diagnosis of feline infectious peritonitis: Update on evidence supporting available tests. Journal of Feline Medicine & Surgery, 20 (3), 228-243.
Shirato, K., W., C. H., & Rottier, P. J. (2018). Differential susceptibility of macrophages to serotype II feline coronaviruses correlates with differences in the viral spike protein. Virus Research, 255, 14-23.
Takano, T. A. (2019). Antiviral activity of itraconazole against type I feline coronavirus infection. Veterinary research, 50(1), 5.
Takano, T., Akiyama, M., Doki, T., & Hohdatsu, T. (2019). Antiviral activity of itraconazole against type I feline coronavirus infection. Veterinary research, 50(1), 5.