FIP – What is behind the dreaded cat disease?

FIP is an abbreviation and stands for Feline Infectious Peritonitis. But what is it? Let's start with a classic definition:

• F stands for Feline : The word comes from Latin and means cat. It indicates that FIP ​​is a cat disease.
• I stands for infectious : This indicates that it is a disease caused by an infection. The infection occurs via a coronavirus. This means that FIP ​​is not contagious per se, but the coronavirus, which can mutate into FIP in a cat's body, is.
• P stands for peritonitis : This indicates a common symptom of the infection. Peritoneum is Latin and means peritoneum in German. The peritoneum - the skin that surrounds the abdominal cavity and the organs - often becomes inflamed when infected. In this case, large amounts of fluid often collect in the abdominal cavity. For this reason, the infectious disease is also known as contagious inflammation of the peritoneum.

The peritonitis caused by the infection can migrate through the upper body into the pleura . Some infections also occur without fluid accumulation. A distinction is therefore made between wet FIP ​​with abdominal or thoracic cavity effusion and dry FIP without fluid accumulation.

Cat owners are warned about FIP ​​time and again. Although the infection is not one of the standard cat diseases and only occurs in an estimated 1 to 2% of animals worldwide, the course of the disease is usually fatal for the affected cats. We will show you below how the infection occurs and which cats it is particularly dangerous for.

How the infection occurs and which cats are particularly susceptible

Feline infectious peritonitis is caused by a coronavirus from cats – FCOV (feline coronavirus) for short.

FCOV as a trigger: Spread of coronavirus in cats

An infection with coronaviruses is initially nothing serious for your house cat and is not a reason for concern . Instead, coronaviruses are actually quite common among our furry friends and can be transmitted in a variety of ways. They mostly attack the gastrointestinal tract and manifest themselves through classic symptoms of illness such as diarrhea , Vomiting or cat fever. Sick cats therefore excrete the corresponding coronavirus in their feces.

Unlike feline leukemia viruses (FeLV), for example, coronaviruses survive for a very long time and can still be contagious weeks later - even if the transmission rate decreases over time. Other cats eventually absorb it through their feces by inhaling it or swallowing it. After transmission, the virus settles in the lungs or intestines, but is fought off by the immune system with antibodies . If your cat's immune system is particularly intact, symptoms may be absent altogether. Nevertheless, excretion in cat feces often extends over several months until there are ultimately no more pathogens in the body.

Even the smallest particles of feces are often enough for transmission - so infection does not only occur in the litter box or in the wild, but can also occur, for example, via textiles that the carrier cat comes into contact with during its illness: pillows, baskets, clothing or similar. Once the coronavirus is there, it spreads almost unchecked, especially in households or accommodations where several kittens live together. Special hygiene or isolation can help, but are often difficult to implement or put the cats under additional stress, weakening their urgently needed immune system.

The feline coronavirus can also be transmitted to conspecifics via saliva and nasal secretions – but not to humans.

How do cats get FIP?

While FCOV can be active and contagious in the cat's body for months, this does not mean that your cat also suffers from FIP. The cat disease FIP is a mutation of the coronavirus. In order to understand how it develops, a short excursion into virology is useful:

Basis: How viruses multiply and mutations occur

Whether it's a cat, mouse, dog or human - a viral infection always follows the same course. Viruses are tiny molecules that penetrate living cells. Once the pathogen has made it into the body, it immediately begins to multiply. This happens through replication with the help of a host cell: the viruses seek out cells in the body of the infected cat that reproduce the virus's genetic material and release it thousands of times over. During this process, changes in the genetic material - so-called mutations - occur again and again. Some have little effect on the clinical picture, others change it significantly. A rare but very aggressive mutation of the coronavirus is the FIP virus .

Corona becomes FIP: What happens when it mutates

If the coronavirus mutates in the cat's body and becomes the FIP virus, your beloved four-legged friend will not give up without a fight and will not immediately feel bad. The immune system is still trying to get rid of the viruses in the body. The defense is carried out with the help of so-called phagocytes, which recognize the viruses as intruders, surround them and eliminate them.

The problem: FIP viruses have mutated so much that they can infect the phagocytes. If this happens, the pathogens enter the cat's blood and spread throughout the body .

Outbreak of FIP: Infection does not necessarily mean disease

Due to the previous corona infection, the cat's body has already developed antibodies that can immediately begin fighting the FIP virus. This can work wonders: If the immune system is particularly strong, it can suppress the FIP virus so well that a symptomatic illness from which the cat suffers only appears years later or may even not occur at all.

The situation is different for already weakened kittens, whose immune response is less strong. FIP can therefore be particularly dangerous for the following groups :

• Young cats : The immune system of kittens up to 2 years of age is not yet fully developed. In addition, the risk of transmission of the coronavirus from mothers to their young is particularly high due to the close living and feeding.
• Old cats : The FIP virus is also particularly risky for senior cats. Their immune systems are often weakened, and age-related pre-existing conditions or nutritional deficiencies often make things even worse.
• Sick cats : Of course, it is not only old cats that can suffer from chronic diseases – sick animals are also a group at risk of FIP. Their immune systems are usually already quite busy and are less able to cope with a viral infection.
• Stressed cats : Stress can also massively weaken the immune system and increase your cat's susceptibility to FIP disease. What causes stress in your cat is extremely individual and depends on character and habits. Common factors include:
  • Adjustment due to moving, exit restrictions or new conspecifics
  • Tension due to problems with other animals or people
  • Veterinarian visits
  • Territorial fights or large groups in close proximity

However, the disease is not only possible in cats that belong to the groups described. If the viruses are particularly aggressive, they can also seriously affect otherwise healthy cats. And it is not just our house cats that are affected: FIP affects every type of cat - from domestic cats to wild cats and big cats.

How to recognize FIP and how the disease occurs

If you're lucky, your pet has a fully intact immune system and is fit enough to keep the viruses at bay and prevent them from breaking out. But unfortunately, that's not always the case.

However, once it has broken out, it is even more important that you seek medical attention and take action quickly.

Classic symptoms of a FIP infection

By recognizing symptoms early and reacting accordingly, you can at least ensure that your furry friend experiences as little suffering as possible. The most common signs of FIP in the first stage of the disease typically include:

• Vomiting and diarrhea
• Runny nose and discharge of nasal and tear secretions
• Conjunctivitis and nictitating membrane prolapse
• Long-lasting fever
• Loss of appetite and weight loss
• Fatigue and apathy
• Jaundice of the skin or mucous membranes
• Disturbances of consciousness or the central nervous system (tilted head, coordination and balance difficulties, cramps, etc.)
• Depending on the type of disease:
  • Increase in abdominal circumference (wet FIP ​​abdominal cavity)
  • Difficulty breathing (wet FIP ​​chest cavity)
  • Anemia (dry FIP)

The list is long and could certainly be expanded to include a few more points - because occasionally there are also abnormalities in urination , inflammation of individual organs such as the kidneys and other symptoms . There is therefore no strict pattern that the symptoms of the disease follow - be alert at the first possible signs and do not hesitate to go to the vet.

Visiting the vet: How the diagnosis works

The large number of possible symptoms also makes diagnosis difficult. Since feline infectious peritonitis is a viral disease, it can be detected by measuring the concentration of antibodies in the animal's blood . As soon as you suspect that your kitten may be affected, the vet can take a blood sample. The measurement will tell you whether your cat has an FCOV infection. Whether it is the FIP mutation cannot be determined with certainty using the blood sample alone. This requires further tests.

Manifestations of FIP diseases

As already mentioned, there are different forms of FIP . A distinction is generally made between wet and dry FIP. Both can initially manifest themselves through the symptoms listed above and, as the disease progresses - in the second stage - additionally exhibit various specific symptoms.

Humid FIP

Wet FIP ​​is characterized by sometimes massive accumulations of fluid in the abdominal or thoracic cavity. Here, a distinction is again made between FIP with abdominal cavity effusion and FIP with thoracic cavity effusion .

Wet FIP ​​with abdominal effusion

In this form, fluid accumulates in the abdominal cavity and the peritoneum becomes inflamed . The sometimes enormous amounts cause the abdominal circumference to grow rapidly - even though the cats often suffer from diarrhea, vomiting and loss of appetite. Depending on the extent, the masses of water in the abdomen can also press on the organs and cause additional problems. The vet can remove fluid through a puncture - this is yellow and pulls threads. More than half of all cats in which FIP breaks out suffer from what is known as ascites .

Wet FIP ​​with thoracic cavity effusion

In wet FIP ​​with thoracic cavity effusion, fluid also accumulates - but not in the abdomen, but in the chest cavity . This is usually accompanied by inflammation of the pleura and visually matches the fluid in the abdominal cavity, as can be seen during a puncture. Due to the proximity to the lungs, thoracic cavity effusions - also known as pleural effusions - often lead to breathing restrictions , which, depending on the extent, can also result in shortness of breath .

Dry FIP

Dry FIP occurs with little or no fluid accumulation in the body - but other symptoms develop in the long term. These include, for example, clumping of tissue and inflammation that spreads throughout the body. Although they occur more frequently in the abdomen, almost all organs - including the eyes, brain and skin - can be affected. A common consequence is anemia , but nictitating membrane prolapse, jaundice and neurological deficits also indicate a dry form of FIP.