Feline Infectious Peritonitis is caused, indirectly, by a coronavirus. It affects only cats. It is what we call a sporadic disease - striking here and there - rarely twice in the same household.

There are many strains of coronavirus, only a few of which cause disease. When a cat is exposed to a dangerous strain of coronavirus, the virus enters the pet's white blood cells and, in this way, spreads throughout the body.

Any cell in the body that is infected with these virus become a target of the cat's own immune system. It is this inflammation, misdirected at the cat itself, that causes the disease.

Where Do Cats Catch Coronavirus?

Coronavirus is most common where multiple cats live. It moves between cats through stool-contamination. So the litter box in multiple cat households is a good place to find the virus. For the same reason, it is more common when cats are crowded into limited areas. The initial mild disease lasts up to a few months. In closed households with up to five cats, the virus eventually burns itself out. But if new cats are continually being introduced or the cattery has more cats, the virus may lurk there indefinitely.

The coronavirus is not a hardy virus outside the body - most household cleaning agents destroys it quickly. An excellent disinfectant is ordinary generic household bleach diluted one part bleach in twenty parts water. For the bleach to be effective, heavy soiling should be removed first with detergent. The virus can not survive in a dry environment outside the cat for more than a day or two. But damp cool areas allow it to survive much longer.

What Signs Will I See If My Cat Had FIP?

The type of feline corona virus that are the cause of FIP are the enteric coronavirus. These are the ones that affect the digestive system. The first signs of Coronavirus infection are quite mild. At most, a gastrointestinal upset with diarrhea. But in a small percentage of cats, rather than dying out, the coronavirus mutates in cells called macrophages - stimulating an attack on the cat's own defense mechanism. In whatever organ in the body that this occurs, clumps of the cat's own defense cells form pyogranulomas that eventually destroy the organ. This outcome is more likely to occur in cats whose immune system is already working imperfectly due to their young age or infection with feline AIDs or feline leukemia. Once the coronavirus has mutated, it can no longer affect a different cat.

In most cats nothing more develops than digestive upsets, the infection passes and the cat is again virus-free. But in FIP cats, the virus persists. Depending on the virulence (strength) of the virus strain and the cat's own immune system, many months or years can pass before the cat's body mounts an inflammatory response aimed at the tissues that harbor these viruses.

Problems usually begin very gradually; the first signs are no more than poor grooming, spotty appetite and weight loss. The pet just appears worn out.

When your veterinarian examines the cat, he/she might detect a low-grade fever (103+F). At this point the disease can take one of several directions.

The most common form is known as the wet or effusive form of FIP. In this form, fluids, rich in protein, build up in the cat’s abdomen or chest.

Effusive Form Of FIP:

If the majority of the fluid is in the cat's abdomen, it gives the cat a pear-shaped, pot bellied appearance. If the majority of the fluid is in the chest, the cat will be very uncomfortable trying to breath. The fluid, when seen in X-rays, gives the affected areas a "ground glass" appearance.

Non-effusive Form Of FIP:

The non effusive or dry form of FIP, often attacks the brain or the eyes. Some cases are a combination of the wet and dry forms.

Cats with the wet form of FIP are often anemic, depressed and running a fever. Their gums and eyes are often yellowish due to liver failure. Many of them also drink excessively due to kidney failure. When the disease is advance, it can be diagnosed from the characteristics of the fluid in the cat's abdomen. A simple apparatus called a refractometer is used to do this.

Cats with the dry form of the disease sometimes have neurological problems that result in lameness, seizures, and a tipsy gait. Other dry-form cases show eye inflammation and blindness.

We often do not recognize the dry form on the cat's first hospital visit because so many other diseases have the same signs. It is only as the disease progresses that an FIP diagnosis becomes apparent.

What Kind Of Cats Get FIP?

Feline Infectious Peritonitis is commonest in younger cats or those recently exposed to large numbers of cats. There may be genetic factors that influence susceptibility to the disease after exposure to the virus since most exposed cats never get ill.

It seems to be triggered by other diseases as well as stress which is why it is so common in animal shelters.

Many cats with FIP are also positive for feline leukemia or feline immunodeficiency virus. This is because infection with either virus makes it more likely that the cat's immune system will malfunction when coronavirus is present.

It is also more common in the high stress environment of crowded cateries.

How Is The Disease Diagnosed?

There is a blood test for coronavirus . The problem is, most cats that have confirmed exposure do not have FIP. The test can not tell the cats that recovered from coronavirus from those that are ill from it. So a negative antibody test might tell us that the cat does not have FIP. But a positive test result is only an indication of FIP if the cat is ill with FIP-like symptoms. Compounding the murkiness of this test is the fact that cats with advanced FIP may also be negative.

So at this time, we have to make the diagnosis based on circumstantial evidence. The telltale signs of FIP are an increase in your cat's total blood protein and gamma globulins. When we find that these levels are elevated and the cat is ill with signs suggestive of FIP, then FIP is the most likely cause. The presence of protein-rich fluid in your cat's abdomen or chest further confirm the diagnosis. Cats sick with FIP also tend to have low serum albumin. If the albumin to globulin ratio is is less than 0.8, there is even more chance that the problem is FIP.

If fluid is accumulating in your pet, we check it's protein content. If the protein content is over 3.5mg/dl, it is quite likely that the cat has FIP.

Polymerase Chain Reaction Test (PCR):

This is the most sensitive test for the presence of enteric coronavirus. But it can not yet distinguish the mutant, disease- causing strains from the ones that cause no serious health problems. The test is currently being refined which may make this possible.

The only 100% effective test that we have at this time is an evaluation of a biopsy specimen removed from an affected organ in the cat.

What Will Happen To My Cat With FIP?

I have never had a cat survive long after a confirmed the diagnosis of FIP. Sometimes, with supportive care, the pets will perk up for a while, but their general health slips down hill rapidly.

No disease - not even feline leukemia - is as frustrating for veterinarians or owners to deal with, as is FIP. From the time I see them, these cats are dejected and depressed and all my attempts to relieve their suffering seem ineffective. When owners resist my suggestions that these cats be kindly put to sleep, I have referred them out for various unusual alternative medicine techniques. I cannot remember a single instance where I felt that the cat benefited. But at least, the owners felt they had exhausted all that both traditional and alternative medicine had to offer.

When you know that your pet has FIP, you need to think about what you will do for your cat when life for it is no longer pleasant. Veterinarians can help with life support and some palliative treatments. But FIP is a steady slide down hill. There will come a time, soon, when you will need to make the decision to put your cat to sleep. Do not extend its life beyond what is kind to your pet.

Some treatments may help in giving short-term remissions in a small percentage of cats. These include nutritional support with vitamins, enriched diets and corticosteroids.

Are There Any New Or Experimental Treatments We Might Try?

If you can not bring yourself to face the inevitable, there are some experimental treatments:

Suppressing Your Pet's Immune System:

FIP is caused by the cat's own immune system. If we cripple this system, the cat might temporarily improve. Steroid medications, such as prednisone and certain anti-cancer medications, such as cyclophosphamide occasionally give your pet temporary relief.

Good Nursing Care:

Removing fluid from your pets chest or abdomen through suction will give temporary relief. However, the fluid will reform and with repeated removal, the pet's protein supplies will be depleted.

Anti-viral Drugs:

There have been a few studies that suggest that feline interferon might be useful in prolonging the lives of FIP cats. However, the most recent 2007 study that I know of, found that it was no help.

Alternative Medicine:

There will always be herbalists, chiropractors, naturopaths, homeopaths , nutritionists, acupuncturists and practitioners of other obscure arts that claim to be able to cure anything. They will get up your hopes by telling you what you wish to hear. I do not suggest you use them.

Should My Cat Be Vaccinated Against FIP?

There is a single vaccine on the market for the prevention of FIP. It is Primucell FIP intra-nasal vaccine manufactured by Pfizer. This vaccine is manufactured from virus engineered to survive in the cat’s nasal passages but not in the body. The vaccine is applied in the nose at 16 weeks of age and a second time 3-4 weeks later. Yearly revaccinations are recommended.

I no longer recommend giving this vaccine to house pets because it appears to hold more potential risk than benefit in these situations . Also, many kittens have already been exposed to coronavirus by the time they are vaccinated. There may be a role for this product in cateries or animal shelter situations or when cats from individual homes must be transferred to multi-cat households.

What Things Can I Do To Protect My Other Cats?

If you have a cateries or a multi-cat household that does not accept new cats, you can use the current blood tests to determine if the group is coronavirus free. Cats that have no coronavirus exposure will not develop FIP.

If you want to add a new cat to pets that survived an FIP death in the cat group, wait 3 months before doing so. This does not guarantee anything - but it is a prudent option.

Minimize inter-cat stress among your cats with sufficient space, and a blend of cats with complimentary personalities.

Practice good nutrition, sanitation and general disease prevention among your cats.