Feline Infectious Peritonitis: everything you need to know

One of the most interesting conferences given in the framework of the International Feline Medicine Conference organized by AAMeFe at the end of last year was the one delivered by Dr. Richard Ford on Feline Infectious Peritonitis (PIF). In his talk, of high level and a clear academic tone, the renowned specialist provided several key concepts for the management of this pathology that veterinarians so commonly encountered. However, the most interesting concept came from the diagnostic side, and it was a fairly simple tip: according to Ford, "with a proteinogram you can diagnose the PIF".

Ford began his presentation by commenting that PIF is a disease that has fascinated veterinarians for 25 years, due to its complexity in diagnosis and prognosis. When analyzing their history, we see that the most susceptible population are the small kittens, from two months to two years of age, but also the cats of more than eight years. "Is it more common in the male than in the female? It has been said many times, but this difference is not so important, there is no gender predisposition. What I want you to understand is that there is a genetic predisposition for the development of the PIF. In some races, such as Persians or Himalayas, more cases are observed, "Ford said.

Then, he went on to explain how the pathology originated. And at this point commented a novelty: the PIF is not contagious. "There are two types of coronaviruses, I and II. The first is benign, but the second, which causes PIF, is very virulent. There are a number of cats infected with coronaviruses, it is estimated to be 80%. But those with type I are non-ill carriers, they never have clinical signs such as diarrhea or intestinal inflammation, healthy carriers eliminate the virus through feces, others are becoming infected, for example, infectologists believe that the pattern of The infection of the females to their young is due to the feco-oral contact.As the infection is spread, mutations also occur in the virus.In some cats with a genetic predisposition, the virus mutates from type I to II, and it is in these cases that the PIF develops, the more times the virus is transmitted, the more mutations there will be, a priori, it is impossible to know which cats are predisposed, and therefore it may happen that, within the same group of cats, just some develop pathology.But among those who suffer from it, mortality is 95%. That is why we affirm that PIF is not contagious, and because of this situation it is that the different PIF vaccines that were created over time have not worked so far, "said Ford.

Within the clinical presentation of the PIF, the specialist indicated two forms. The first, best known, is the PIF with effusion, with spillage. It is the easiest variant that can be diagnosed, because an abdominal fluid appears that has a viscous consistency and a dull yellowish color, which can be extracted and analyzed. Due to the nature of the virus, this fluid has a very high protein content, which in turn causes vasculitis. The proteins are so many that at a glance in the liquid small clots can be observed, as if they were blood. This table is enough to diagnose PIF. If we had to make a smear on a porta or a tinciÃіn, few neutrophils and macrophages would be seen, because the abdominal effusion is hypocellular. According to Ford, it is defining a piogranulomatous inflammation, not a pioabdomen. "If you can reach this level of detail, there is no need for laboratory tests to confirm the diagnosis. On the other hand, 15% of cats with the inflammatory form develop a pleural effusion," he said.

However, the main problem is the other way in which the PIF is presented, and it affects between 15% and 20% of cases. It is the dry variant, without spillage, also known as non-inflammatory. It is more complicated and difficult to identify. "I think that if we had an animal with this disease, nor did we realize it, it is very difficult to confirm. The difference between the form with or without effusion is that the latter is chronic and slowly evolving.

It is a granulomatous disease characterized by the formation of solid granulomas, which is difficult to confirm if we do not do abdominal surgery. The diagnosis is complicated because the manifestations in the animal can be confused with an abdominal dysfunction, something can appear in the eyes and in the central nervous system. The clinical signs vary depending on where the lesion is housed. If the PIF compromises the SNC, the prognosis is the worst: they die, "Ford said.

The main clinical presentation of PIF with neurological involvement is posterior paresis. The second, seizures. The third, the ocular manifestations, are the best prognostic. They are treatable cats with an excision of the eye. The signs are uvetosis and precipitate cystic (characteristic of active infection). Any cat with uveís is an important differential to consider PIF. As the uveitis yields, some cats will form a fibrin cord in the anterior ocular chamber. This confirms the presence of uveitis, not PIF, but it is very characteristic of the ocular change that occurs with the PIF.

"We had many infected kittens that did not see well, because they had retinal detachment. It is very possible to see the vessels of the retina simply with a directed illumination. If we see small vessels in the retina it is because it came off," said the specialist.

Another possibility, unusual, is intestinal invagination. Ford told me that he treated a two-year-old cat, which led to the operating room showed multiple granulomas on the abdominal surface. The histology confirmed the diagnosis. "The exploratory abdominal surgery, seeing the lesions in the tissue, helped us a lot, because there was no fluid," he said.

The most fatal lesions of PIF are those of tissues, kidney pyogranulomas, spleen, intestine. "They are enough for the diagnosis, but they are not the cause of death. What causes death are the small infarction injuries that are seen, the vasculitis that prevents circulation. It is very useful to be able to obtain a tissue sample of the abdominal cavity: there may be no granuloma, but if the histology confirms vasculitis, we have a PIF. The best tissue to sample is a mesenteric ganglion. Then, it shows a liver, and finally a kidney " , recommended the American.

Then, Ford criticized the diagnostic tests: "There are many tests that are sold in the market, even in Argentina. But they are not good. Every animal exposed to a coronavirus will test positive for biotype 1, the tests only confirm that. Elisa it is not valid, it is not recognized as a diagnostic test. There is also PCR for coronavirus antigen, but it does not differentiate coronavirus biotype 1 and 2 ".

And after this critique, Ford released the most interesting and practical concept of his entire lecture: "The most important test to diagnose dry PIF is the simplest thing you can ask for: total proteins."

Why? "Simply by determining if the cat has a high level of total proteins, it is enough for us to establish the diagnosis. If it has more than 7.8 grams per deciliter, it is at risk of PIF. Some may say that the protein may be high due to infection or, for example, because the cat is dehydrated. To establish this difference, the constitutive proteins must be observed: albumin, globulin. "

Ford explained it with an example of a two-year-old kitten with 8.8 grams of total protein. "The normal value is 6, and the distribution should be 3 gr. Of albumin and 3 gr. Of globulin. But in this case, there was a huge difference between the proteins. The globulin was very high, but the albumin was low, for the vasculitis the animal was suffering in. If it had been dehydrated, both proteins should have been high alike. This difference between low albumin and high globulin is very suggestive of PIF. Apparently, 75% of cats with dry PIF show this pattern , and also 50% of those who suffer the damp form ".

But what do we do with 25% of cats with dry PIF in which we do not find that difference between total proteins? The diagnosis is further complicated. At this point, Ford recommended entering the page, to the Molecular Diagnostic Laboratory section. There, he said, there is information about a diagnostic method available in the US, a reverse transmission of the polymerase reaction test. Specifically analyze the virus that replicates within macrophages, not the virus in the blood. The diagnosis points to messenger RNAs that replicate coronaviruses in the macrophage, this defines the PIF.

How to treat the pathology
According to Ford, if we are convinced that the cat suffers from PIF, option number 1 is very cheap: administer anti-inflammatory doses of prednisolone. The goal of treatment is to reduce vasculitis, that's why corticosteroids are recommended. The dose is 0.5 mg / kg., Twice a day. And if we have an ocular compromise, any typical corticosteroid would be adequate.

In as much, the abdominal-centesis can be used during several months to reduce the volume of fluid. Those cats come to live two more years, and can be handled in the long term if the owner agrees. The quality of life that is achieved with prednisolone treatment and abdominal-synthesis is quite good.

Why do the different vaccines developed fail? Because the PIF is not contagious, but it is caused by the coronavirus mutation in cats with genetic predisposition.


• Both Feline Coronavirus type I and type II can cause clinical PIF syndrome.
• Some races and lines within the races are predisposed to the PIF. Persian, Balinese, Burmese and Himalayan cats predominate.
• The risk of PIF is higher among cats that live together with others.
• The occurrence is greater in puppies. Clinical signs, if they occur, can take several years to develop.

What is Feline Infectious Peritonitis?

The feline infectious peritonitis It is caused by a feline coronavirus. Coronaviruses are a very large family of viruses, which in humans cause from the common cold to much more serious respiratory diseases.

It is very common for cats to become infected with coronaviruses, but most of the time the effects are not serious. However, on a few occasions, the virus mutates (transforms) inside the body of the infected cat, and it is that mutation that causes the so-called feline infectious peritonitis or PIF in cats.

Symptoms of Feline Infectious Peritonitis

As the Feline Medicine Group of Spain explains, PIF in cats has very diverse clinical manifestations, so there are no clinical signs directly and exclusively associated with this disease.

The most common form of the disease is the so-called “Wet PIF”, which is characterized by accumulation of yellowish fluid in the abdominal and / or thoracic cat cavity. The consequence is obvious and serious respiratory problems.

The initial symptoms of feline infectious peritonitis are nonspecific and very vague, such as for example that the cat falls into a state of lethargy or loses appetite.

Some forms of this disease also cause inflammatory lesions in the eyes or in the nervous system, which leads to alterations in vision and behavioral problems, trembling gait and tremors.

The disease is very serious and usually progresses rapidly. The most frequent consequence is the death of the cat.

How is PIF spread in cats?

The coronavirus transmission route is what, in medicine, is called gold-fecal. That means that Cats become infected by ingesting the virus orally, when they groom themselves or when they eat and then eliminate it through feces.

Cats can become infected by coming into contact with the feces of other infected cats.

What percentage of home cats are infected?

It is estimated that between 25% and 40% of homemade domestic cats are infected by coronaviruses. The percentage rises to 80% -100% of cats that live in large groups in homes, shelters or hatcheries.

Although coronavirus is the cause of PIF, that a cat is infected with coronavirus does NOT imply that it will develop feline infectious peritonitis.

Compared to the number of cats infected by the virus, those with PIF are very few. It is only if the virus mutates when the cat develops PIF. The problem is that, as of today, the causes of coronavirus mutation are still unknown.

Infectious Feline Peritonitis: tips for its prevention

Feline infectious peritonitis is very rare in home cats. In any case, there are some measures that help minimize the risk of disease occurrence:

Avoid stressors (house changes, schedules, routines, not providing a safe area for the cat inside the home, etc.). Stress affects the cat's defenses and exposes it to disease more easily.

Maintain a proper deworming routine.

Do not vaccinate and spay or neuter the same day, especially if the cat is not well.

Maintain proper hygiene of the sand tray.

In houses where several cats live together, it is very important:

That each cat has its own sandbox.

That each cat has its own feeder and drinker.

Have an individual excrement shovel for each of the cats.

Empty the sandboxes at least once a day.

Remove all the sand and disinfect the sandboxes, at a minimum, once a week.

Keep sandboxes away from the food area.

Vacuum the area around the sandboxes on a regular basis.

Trim the hair of the buttocks of long-haired cats.

How to introduce a new cat at home if the previous one died of PIF?

Some people who have had a cat with PIF want to be sure that if they adopt another, they will not be infected with the virus that the previous one could have left in the environment.

If the PIF deceased cat does not live with more cats, it is recommended to wait 2 months before introducing a new cat in that house to minimize the risk.

If you live with more cats, the remaining ones are likely to be carriers of the coronavirus, so before introducing a new cat it is wise to wait several months. In addition, it would be appropriate not to introduce kittens under 16 weeks of age, who are more exposed to infection.

Is there a vaccine against Feline Infectious Peritonitis?

Yes, the problem is that the efficacy of the vaccine is unknown, since the different studies carried out to prove its effectiveness show contradictory results. According to GEMFE experts, the general opinion is that it is not especially effective. In addition, its use is only allowed in cats over 16 weeks of age, and at that age most cats are already infected by the virus.

_ Bibliography and links of interest Mars Inc. Veterinary Oral Health Council (English) American Veterinary Medical Association (English) Tell us your case If you have any questions about what you just read, the Nutro veterinary team will clarify it to you personally in our FACEBOOK or TWITTER. Do not stop writing to us!