Cat diseases are always an urgent topic to discuss in the sphere of cat-fanciers, especially when we are unable to help our pets.
That's why I'd like to touch on the question concerning one dreadful viral disease our owners and veterinaries have almost never met before but which in the view of appearance of nurseries for purebred cats in our country now is arising in full measure. The matter concerns so-called coronavirus infections.
Coronavirus is a spherical particle 100 nm (one ten-thousandth of millimeter) across diameter, has relatively complicated structure and capsule made of proteins and lipids with big club-like projections (crown). The genome of virus is a single-stranded understandable (+) RNA with a molecular weight 6-8 million.
Coronaviruses are widely spread pathogens of serious diseases in animals (often lethal). There are two main kinds of diseases in cats caused by these viruses: feline coronavirus enteritis and feline infectious peritonitis. Feline enteric coronavirus (FECV) and feline infectious peritonitis virus (FIPV), as is known now, are similar cultures of one virus. They are safe for humans.
FECV most often strikes cells of mucous membrane of small intestine and causes sdiarrhea (flux). Kittens from one-two months are especially perceptive to this virus. The disease usually begins with vomiting and then develops into flux, which lasts for 2-4 days. After that the recovery begins. Still animals stay virus carriers for a long time, and virus is excreted with faeces and easily affects other kittens if they use the same toilet. Although this is a very widespread disease and kittens are often ill with it, it is not so dangerous as to attract large attention.
Infectious peritonitis (FIP) appears suddenly and as if spontaneously in kittens and young animals. In contrast to a disease described above this illness almost inevitably ends with death. Virus affects macrophages (white blood cells) and destroys them, thereby opening gates to infection in tissues. There's no effective preventive vaccine or treatment for this disease. Most often one can determine the disease by a gradually swelling belly in the presence of high fluctuating body temperature. This is so-called wet FIP (dropsy). There is a dry form, which happens more rarely when there're no external signs of disease but there are high body temperature, langue, loss of appetite and weight. In last few years the disease has become one of the most serious problems in nurseries of USA. The larger and the more congested is the nursery the larger is the number of cases of FIP in it. It is impossible to save diseased animals. Moreover, it is even impossible to make an early diagnose in order to isolate an ill animal. Absolutely healthy animals may give positive results of immunological tests if they are carriers of relatively safe FECV, which doesn't differ immunologically from FIPV.
Intensive research on the problem of feline infectious peritonitis held in USA lately has shown the following. Factors that increase the risk of falling ill with FIP are:
- joint keeping of large amount of animals;
- young animals, especially kittens under 4 months;
- bad care and feeding;
- high level of stresses in nursery;
- exchange of animals, especially kittens;
- outer contacts: coupling, traffic, exhibitions;
- genetic predisposition.
It's important to say that coronaviruses are transmitted from one animal to another mainly through faeces. The transmission through saliva is also possible, although, apparently to a lesser extent. Virus transmission through the air is considered to be unlikely. Yet FIPV lives and reproduces inside blood cells but not intestines and isn't excreted with faeces (or even with saliva)! In other words, FIPV is most likely not to be transmitted from one animal to another, i.e. in the ordinary sense is not infectious. How does this dreadful disease apppears? According to the latest data, the disease (FIP) arises as a result of infection of enteritis coronavirus (FECV), which then mutates into a form, which is able to affect blood cells. It is the enteritis coronavirus, i.e. FECV, and not FIPV that is infectious and is transmitted from one animal to another through faeces. Therefore everywhere, where the coronavirus infection appears the FIP may emerge.
The main applied conclusion for these observations is to fix measures to reduce the risk of coronavirus enteritis infection of animals in nursery. Here are some recommendations of American scientists and vets:
- keep a cat toilet clean, change filling material more frequently and disinfect the toilet from time to time; provide not less than one toilet for every two cats!
- there should not be more than 8-10 cats in one house;
- queen with kittens should be isolated from other animals until kittens are three months old;
- any new animal should be isolated at least for one month;
- in case of high titer of coronavirus in queen (if suspected that it was infected with coronavirus), feeding of kittens without mother is recommended (starting from 4-6 weeks) and isolation of these kittens from other animals until they are saled. It was noticed that people could hardly be coronavirus carriers so one shouldn't be afraid of visitors.
A.S. Spirin, member of the Academy. Magazine "Friend"
Translated by Tatiana Karpova (Moscow)
(MSU, Biology faculture, Dep. zoology and ecology).