Feline infectious peritonitis is one of the most serious infectious diseases that affect felines, due, among other causes, to the serious prognosis it has and as a consequence of the non-existence, to date, of a truly effective treatment.
It is more common in young cats under two years of age and in cats over 12 years of age, with a much higher incidence in cats living in communities. The disease develops when the feline enteric coronavirus mutates, and it is from this moment on that, depending on the cellular immune status of the feline, the more severe dry or wet form of the disease will develop. In this article on our site we will cover in depth everything you need to know about Feline Infectious Peritonitis (FIP), a disease of such concern to cat keepers and so devastating to felines.
What is feline infectious peritonitis?
Feline infectious peritonitis (FIP) is a serious, debilitating, progressiveinfectious, and in most cases fatal, infectious disease that affects to wild and domestic cats. It is a process of viral origin and worldwide distribution that has a large immune component.
The incidence of this disease is higher in kittens under 2 years old and in over 12 years of age, especially those of pure breed from farms or those who live in groups, due to a greater possibility of contagion of the virus that causes it.
This virus, whether or not it ever produces peritonitis disease, affects the digestive system in cats.
What virus causes FIP in cats?
The feline coronavirus (CoVF) is the agent that can lead to the development of FIP. It is an enveloped RNA virus of the Coronaviridae family and Alphacoronavirus genus. It is estimated that up to 90% of cats living in communities and up to 50% of those living alone are seropositive for FCoV. This virus enters orally and goes to the intestinal cells (enterocytes), where it multiplies causing mild diarrhea from which they heal. Shedding of the virus begins two or three days after infection and can last for a long time, even for the life of the cat.
However, in less than 20% of those seropositive cats the virus mutates, giving it the ability to infect defensive cells called macrophages and thus spread throughout the feline's body, giving rise to the FIP disease. In the development of this disease, the state of the cat's cellular immune system is essential, so that:
- If the cellular immune system is strong, the disease does not occur.
- If the cellular immune system is partially suppressed, dry FIP. develops
- If the cellular immune system is severely suppressed, Wet FIP. develops
How is feline infectious peritonitis spread?
By affecting the digestive system, FIP is mostly transmitted indirectly through feces or any object contaminated by the same, especially the sandboxes where it can remain viable for up to seven weeks.
On the other hand, the virus can be transmitted directly through saliva and a case of transplacental infection has even been described. As we say, it is a very contagious disease, so it is essential to isolate the contagious cat from the rest in case several cats live in a home.
Is feline infectious peritonitis contagious to humans?
No, FIP cannot be spread to humans. This is a virus that only spreads between cats, so people can't catch it.
Feline Infectious Peritonitis Symptoms
The symptoms common to the dry and wet forms of FIP are non-specific symptoms: fever, depression, fluctuating anorexia, pallor of mucous membranes or jaundice, progressive weight loss and stunted growth in kittens.
Symptoms of dry FIP
In the dry form of FIP, there is a type IV hypersensitivity characterized by the formation of pyogranulomatous infiltrates often around blood vessels. These piogranulomas will produce variable clinical signs depending on the organ they affect:
- In the kidney, they will produce clinical signs of kidney disease.
- In liver, liver failure.
- In lung or pleura, dyspnea and respiratory signs.
- In the intestine, colon, cecum and ileocolic lymph nodes, it will cause digestive signs such as vomiting or diarrhea.
- In the brain, neurological signs such as seizures, altered mental status, behavioral changes, cranial nerve deficits, vestibular signs, hyperesthesia, ataxia, tetraparesis, and abnormal postural reactions.
Skin signs may also appear, such as non-itchy erythematous papules on the trunk and neck, subcutaneous edema, skin fragility syndrome and nodules on the neck and forelimbs. Generalized synovitis can be seen in the joints, and the eye can also be affected with anterior uveitis, chorioretinitis, hyphema, hypopyon, keratin precipitates, and retinal detachment.
Other clinical signs that may be seen in cats with dry FIP are abortions and metritis.
Symptoms of wet FIP
In wet FIP there is infiltration of infected macrophages into the tissue surrounding the blood vessels and subsequent deposition of immune complexes in the vessels along with complement activation resulting in vasculitis, damage to the vascular endothelium and leakage of serum and albumin proteins from the capillaries. It is the most serious form and with the worst prognosis of the disease.
It is characterized by the formation of painless effusions composed of a yellowish straw-colored liquid with albumen proteins located in:
- Accumulation of fluid in the abdominal cavity (ascites) in the vast majority of cats.
- Pleura (pleuritis) in up to 40% of cats.
Chin, scrotal edema and pericardial effusion leading to heart failure may also occur.
The occurrence of jaundice is more common than in the dry form due to liver failure or immune-mediated hemolytic anemia and the interference of high levels of tumor necrosis factor alpha that interfere with bilirubin transporters into and out of liver cells. Neurological and ocular signs of the dry form may also appear.
Diagnosis of Feline Infectious Peritonitis
The minimum to perform in a cat with signs of FIP is a blood test, where leukocytosis with lymphopenia and neutropenia can be seen (increased white blood cells but reduced number of lymphocytes and neutrophils), along with a non-regenerative anemia typical of a chronic inflammatory process. However, this is very non-specific and can fit in with numerous diseases that cats can suffer from.
Serological testing for feline coronavirus is of no use as many cats are positive and do not have the disease. The probability of a cat presenting FIP increases with:
- An albumin/globulin ratio less than 0.4.
- A positive Riv alta test, however septic exudates and lymphomas can also be positive. However, it is a good test to rule out the disease, with 97% reliability.
If there are neurological signs, a sample of cerebrospinal fluid should be taken, where an increase in protein (50-350 mg/dl) and cells (100-100,000 nucleated cells/ml) will be seen.
To diagnose the type of feline infectious peritonitis, the following is done:
- Diagnosis of wet FIP: a sample of the liquid from the ascites or pleurisy should be taken, which should be viscous, yellowish-reddish, without bacteria, with many proteins (greater than 35 mg/ml) and few cells (less than 5,000/ml). The best test for diagnosing the wet form is immunofluorescence to look for the virus in the effusion fluid.
- Diagnosis of dry FIP: in many cases the diagnosis is made when the cat has unfortunately already died, taking samples of the organs of the. In the living animal, invasive tests must be performed to take biopsies. In both cases, the most reliable diagnosis is obtained through the immunohistochemical technique with coronavirus antigen staining from these samples.
Feline infectious peritonitis treatment
Is there a cure for feline infectious peritonitis? Unfortunately, today FIP continues to be a disease with a very poor prognosis that is not curable, although there have been cases of remission, especially of the dry form.
The therapy is based on a symptomatic treatment consisting of:
- Protein-rich diet.
- Administration of proteolytic enzymes.
- Vitamin complexes (A, B, C, E).
- Pleural effusion drainage if respiratory capacity is compromised.
- Fluid therapy for fluid replacement.
- Injection of dexamethasone into the abdominal or thoracic cavity (1 mg/kg every 24 hours until the effusion no longer occurs, up to seven days; if there is an effusion in both cavities, the dose per cavity should be be divided).
- Coverage antibiotics.
- Prednisolone and cyclophosphamide to decrease the severity of immune complexes and vasculitis by depressing the humoral immune system.
- Recombinant feline interferon omega (FelFN-w) as an enhancer of the cellular immune response.
In recent years, hopes of finding a cure for this disease have increased, as various studies have been carried out assessing the efficacy and safety of numerous active ingredients, most of them in cells, but others already they are being tested on cats. Among them, two drugs are showing good efficacy and safety in the treatment of FIP: the 3C protease inhibitor GC376 and the nucleoside analog GS-441524. However, more studies are still needed before they are commercially available in this species.
Life expectancy of a cat with FIP
The prognosis of the PIF is very poor. Unfortunately, most cats die within weeks ormonths of diagnosis. In addition, if they develop a wet form, a large number of them are usually slaughtered within 10 days in order not to prolong the animal's suffering.
Feline infectious peritonitis is a disease that kills around 0.3-1.4% of cats in the world, being the main infectious cause of death in young cats, and is a source additional threat to endangered wild cats.
If the disease is diagnosed, the care of a cat with FIP is that described in the previous section on symptomatic treatment, so it will be necessary to establish an adequate diet and follow the guidelines established by the vet.
How to prevent FIP in cats?
Since feline infectious peritonitis is a mutation of the feline coronavirus, it is essential to try to prevent the latter. Thus, there is no vaccine for feline infectious peritonitis, but there is a vaccine for feline coronavirus However, it is important to highlight that it is very difficult to control this disease through vaccination, since it is given when the cats are between 16 and 19 weeks old, an age at which many cats have already had contact with the virus.
Again, we insist on the importance of isolating the cat infected with FIP from the rest of the cats in the event that several cats live in the same household.
