About FIP

Feline Infectious Peritonitis

Article taken from and slightly modified fromhttps://zverolekarka.com/fip/

Infectious peritonitis in cats, better known as FIP, is a relatively common, incurable and fatal disease in domestic cats. FIP is one of the biggest killer kittens and young adult cats. It mainly affects cats kept together with other cats, such as shelter cats and cats from larger kennels.

FIP is among the three fatal diseases of cats marked with a three-letter abbreviation starting with the letter F. Of these diseases is the fastest course. The other two diseases are FeLV, feline leukosis, and FIV, cat AIDS.

In addition to domestic cats, some felines can become ill, especially the cheetah. The disease is not transmissible to other animals or humans.


The agent is a feline coronavirus called FeCoV. Coronaviruses are quite large viruses with a pronounced ability to change. This causes two subtypes of the virus: non-virulent FECV, intestinal coronavirus causing transient diarrhea, and virulent FIPV, FIP. The FIP virus further comprises two distinct serotypes.

Coronaviruses are relatively resistant to the environment, can be transferred to articles or clothing and can survive for up to seven weeks at room temperature when dry. However, most conventional disinfectants destroy them, especially chloroform, chlorhexidine, ether, methanol, lysole, povidone iodide (betadine) and benzalkonium chloride are particularly effective. Temperatures above 56 ° C destroy them in 15–60 minutes.


As such, FIPV is infectious very rarely. It is strongly bound to host tissues and is released into the faeces or urine only if the inflammatory lesion formed is injected into the intestine or kidney duct.

However, the intestinal coronavirus FECoV is infectious and is excreted with faeces from infected cats, sometimes for several months. Permanent asymptomatic carrier is also possible. Transmission is easy through faeces contaminated objects, especially if the cat’s toilet shares more cats.

The variability of coronaviruses means that new mutations, new strains, are constantly forming in the intestines of infected cats. Accidental loss of one intestinal coronavirus gene causes a change in its affinity, instead of intestinal cells it attacks macrophages, one type of white blood cell. This mutant virus is the FIP virus.

Course of the disease

Intestinal coronavirus infection is usually symptom free, sometimes short-term diarrhea occurs. Infected cats, however, excrete virus by faeces and up to 18 months, at least half a year. Repeated infection is possible. Kittens secrete a greater amount of virus than adult cats, and multiplication of the virus also supports weakening of the immune system, for example in case of concomitant infectionFIVThe more the virus multiplies, the more likely it is to mutate in FIPV. Intestinal coronavirus mutates in up to 20% of infected cats.

What happens next depends on the immune status of the organism. In the vast majority of cases, a virus that penetrates macrophages is immediately destroyed, even with infected cells, by the strong cellular immunity of the host.

In a weaker cellular immune response, infected macrophages spread throughout the body. The body’s attempt to overcome infection by antibody production is no longer successful at this point, although antibodies can reduce intestinal coronavirus proliferation. In FIP, however, many antibodies worsen the course of the disease by creating immunocomplexes and developing an uncontrollable inflammatory response. Infectious peritonitis develops.

If FIP is to develop, it usually develops six to 18 months after intestinal coronavirus infection, but may take years. The disease usually affects cats aged three months to three years, 50% of sick cats are under one year. FIP, however, is possible in every cat and at greater risk are also old cats with already weakened immune system.

It seems that purebred cats get sick more often and there is a breeding predisposition to FIP in cats British shorthair, Bengali, Abyssinian, Birem, Ragdol, Himalayan cats and Rex.


According to the clinical picture, two forms of FIP are distinguished: effusive, “wet”, and non-effusive, “dry” FIP.

Wet FIP develops in cats that are unable to mobilize cellular immunity. The presence of FIPV causes a violent antibody formation associated with a hypersensitivity reaction.

It begins with anorexia, apathy, and an elevated temperature that does not respond to antibiotic treatment. Gradually, either the enlargement of the abdominal cavity due to the accumulating effusion or the difficulty breathing due to effusion in the thoracic cavity becomes apparent. Enlarged abdomen is in 85% of sick cats. Sometimes vomiting, diarrhea or jaundice are added.


In dry FIP, the organism is able to keep the inflammatory response under control to some extent, but there are limited inflammatory foci, pyogranulomas, in various organs.

Dry FIP may be relatively long without symptoms, or cause only slight, overlooked problems such as fatigue and gradual weight loss. Sick kittens don’t really grow.

Fatigue, progressive anorexia and alternating fever, which does not respond to antibiotic treatment, is the most common symptom of FIP, but unfortunately nonspecific, which can manifest a great many diseases.

In at least 10% of cats with dry FIP, the brain is damaged over time and uncoordinated movements, hypersensitivity, cramps, polio, personality changes and dementia occur. Certain watery brain can also develop. Changes in the eyes, conjunctivitis and inflammation or bleeding in the anterior chamber are also common. Therefore, in addition to brain and eye involvement, which is present in 60% of cats with dry FIP, joint inflammation and signs of liver or kidney failure may occur.

The effusive and non-effusive form of FIP may pass into one another, the disease may begin as a wet FIP, mobilization of the immune system may temporarily turn into dry FIP, and after the collapse of immunity it may again turn into FIP effusive.

How do we know if a cat has a FIP?

Diagnosing FIP during cat life is rarely simple.

A wet form with exudate in the abdomen or chest is similar to heart, liver or kidney failure, difficulty breathing with exudate in the thoracic cavity can also cause a tumor, and bacterial pleural or peritoneal inflammations are also considered, and toxoplasmosis.

FIP is characterized by anemia, a large number of white blood cells, neutrophils and few lymphocytes. By examining blood plasma proteins, a huge amount of so-called blood plasma is found. globulins, which are all those antibodies produced. The effluent collected is light, yellow, mostly clear, very viscous and sticky, with shaking of the foam.

In the dry form, the finding in the blood is the same as in the wet form. Further, FIP is believed to be a fever that does not respond to antibiotic treatment, especially when signs of eye or brain involvement are present. It is necessary to distinguish FeLV, meningitis, tumors of various organs and tuberculosis.

Rapid tests for antibody detection are quite useless because they cannot distinguish antibodies against FIPV and FECoV. However, they have up to 30% of all cats. Conversely, cats dying of FIP may have very little antibody in the blood.

From the effusions and to a limited extent also from the blood, directly mutated virus can be detected by PCR. This method, on the other hand, is very accurate.

The gold standard of FIP diagnosis is the detection of virus inside macrophages in tissues. Samples to be examined are most often obtained during necropsy of the animal. The diagnosis of FIP, especially the dry one, during a cat’s life is therefore based on the evaluation of many different tests, if it “fits”.

FIP treatment

Until recently, infectious peritonitis in cats could not be cured. In the untreated wet form, the survival time is about two to four weeks, in the dry FIP is 2 to 6 months. Sometimes life can be prolonged by the application of corticoids, but interferons do not have the effect. The prognosis is always poor.

The possibility of curing FIP came in 2017 after clinical trials of a preparation known as GS441524 at UC Davis. Although the treatment has not yet been officially approved, it is possible to access drugs manufactured in China.


Preventing FIP in cat breeds is difficult or impossible. It is a disease associated with intestinal coronavirus. It is very contagious and easy to carry.

To prevent the transmission of coronavirus from a cat that secretes it to a healthy cat, the two cats would have to be completely isolated. They would have to live in different buildings, the virus is also airborne, with separate water and feed bowls, with separate cat toilets including litter and droppings, and the keeper would have to change clothes before coming to an isolated cat.

Risk of FIP development

Intestinal coronavirus antibodies are found in 60% of cats from homes with more than one cat, and virtually all cats from kennels and shelters with more than six cats. These cats can pass on coronavirus for many years, in cycles of infection and subsequent reinfection. FIP in such environment just occasionally occurs, most often in kittens from 3 to 16 months. The risk increases with more animals, if a larger proportion of kept cats are young cats and kittens, when new animals are added and other diseases occur. The outbreak of the disease is dependent on the immune deficiency of the host and is therefore supported by stress, such as a change of owner.

FIP is a sporadic disease despite the spread of intestinal coronavirus. The probability of its occurrence in a home where one or two cats live is 1: 5000. However, in a kennel or shelter environment, the risk can rise to as much as five to ten percent. In addition to sporadic occurrence occasionally FIP appears in the form of some sort of epidemic in breeding, usually happens when the introduction of a new strain of FECoV and overcrowding kittens.

How to disinfect when FIP occurs

If FIP occurs in the home, other cats unrelated to the sick are at no greater risk of developing FIP than any other cat. Kinship increases risk due to congenital predisposition.

The mutated virus itself is not contagious. After the death of the cat on FIP nothing prevents the acquisition of a new cat. It is possible to wait two months for peace of mind, after that time no coronavirus survives anywhere in the household environment. No special disinfection is required.

Vaccination against infectious peritonitis

Vaccination is unreliable and only functions as protection against coronavirus infection as such. There is no point in serologically positive cats that have ever had intestinal coronavirus in their lives. Since kittens can only be vaccinated from 16 weeks of age, it is difficult to ensure that they do not encounter coronavirus by then.

Practically, vaccination against FIP has not been successful and the vaccine is no longer available.