Feline FIP: Understanding a Deadly Cat Virus

I painfully learned about Feline FIP, feline infectiousperitonitis, long before I became a veterinarian. In fact, this virus in cats is amajor reason that I ended up becoming a feline veterinarian. I had never evenheard of FIP the day my kitten suddenly had hazy eyes. All I knew was thatsomething was very wrong with my kitty's ordinarily gorgeous cat eyes. Theyappeared very cloudy inside, and it didn't take long for me to realize that he couldn't see.

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Despite having been incontact with my kitten's regular veterinarian, as I will explain more later, mygut told me I needed to do more right away. Very late that night, my husband and I jumped into our car andbegan a 2 1/2 hour drive to New York City, my precious scared kitty clinging tome all the way.

When we arrived, after alot of tests and differential discussions, I received the devastating news:Noodles had feline FIP. At the time, I had no idea what that meant, except that his veterinarian was telling me he would die.

What is Feline FIP?

Feline FIP is aheartbreaking illness that primarily afflicts kittens, and is almost alwaysfatal. It occurs due to a mutation of one particular strand of the felinecoronavirus (FCoV), of which there are many strands that many cats are exposedto throughout their lifetimes and especially as young kittens. Usually, thereare 2 primary factors that contribute to the likelihood that a cat will developFIP.  The first factor is that the cat comes from a multicat environment, suchas a shelter or a breeding facility. The second is that the cat has sufferedsome recent stress, such as moving to a new household or being neutered.

That said, however,not all cats will develop FIP even if they have had these two primary factors.Not only does the cat have to have been exposed to one particular strand out ofhundreds of FCoV strands, but he also has to have what is believed to be somesort of genetic predisposition to cause the strand to mutate. For example, anentire litter of kittens from a cattery would be exposed to the feline enteric coronavirusstrand yet only one kitten will develop cat FIP. I personally had this happen withone of my clients recently. He purchased two kittens from the same cattery,although they came from different litters, and both tested positive for thecorona virus (more on this testing later). It is safe to assume that bothkittens were exposed to the same strand, since they were born and raised in thesame environment, but only one developed and ultimately died of feline FIP.

Unfortunately, thereare many aspects of feline infectious peritonitis that we still don't fullyunderstand, making it difficult to explain risk factors, to diagnose, and totreat. What we do know is that feline FIP often affects young, innocent kittensand takes their lives.

Symptoms of Cat FIP

gray and white cat with feline fip
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In my personalexperience, I didn't know what could be responsible for the change in my kitten's vision. Just the day before,my kitten was playing with his kitten toys, eating his kitten food and acting,in every way, like a perfectly normal kitten. He had, however, just been seen by the local veterinarian for mild catconjunctivitis and a mild feline upper respiratory infection for which I wasgiving him antibiotics by mouthand cat antibiotic eye drops.

The symptoms of FIP in cats were totally unknown to me. AllI knew was that I was very frightened when I realized he couldn't see, so Icalled the veterinarian right away. Unfortunately, my veterinarian, whom I hadgreat faith in, said to just continue the cat medication and that was all wecould do. He didn't even want to re-examine my kitten again. I was in somesense relieved, and yet, I couldn't shake the feeling that there was somethingmore serious going on. Never did Iimagine that the serious mystery condition was one that would likely provefatal for Noodles.

There are twotypes of feline FIP, which can have verydifferent symptoms. The two forms are a wet (effusive) and a dry (noneffusive) type. Furthermore, unfortunately, the symptoms can be quite vague and canindicate a number of other cat health problems as well.

Cats with the noneffusive type of FIP may have weight loss,lethargy, fever, a poor hair coat,and anemia, but will not accumulate fluid in the abdomen or chest.

The wet, or effusive, type of FIP in cats can share the samesymptoms as the dry form, such as fever, loss of appetite, weight loss, andlethargy, but is primarily identified by the collection of fluid in the abdomenand occasionally the chest. The amount of fluid may increase quickly and makeit difficult for the cat to breathe.

I found out that the cloudy appearance in my kitten's eyeswas caused by a condition called anterior uveitis, or inflammation in the frontchamber of the eye. This condition is one of the symptoms that you may see withfip in cats. It appeared that my kitten, Noodles, had the dry form of felineFIP in cats which was causing the inflammation in his eyes, along with his fever andhis decreased appetite and lethargy.

Diagnosis of Feline FIP

The night I knew therewas something seriously wrong with Noodles, we headed to the AnimalMedical Center in Manhattan, a truly amazing place. At the time, I hadnever seen or imagined anything like it. It looked just like a hospital forpeople, but was for animals. It was there that I learned that the possiblecauses of my kitten's eye problems were Feline Infectious Peritonitis, Feline Leukemia, or Toxoplasmosis. FIP is a diagnosis that is made by ruling outthese other conditions, among others, because there is no single test forfeline infectious peritonitis.

FIP tests are unreliable in providing a definite diagnosis. FIP is diagnosed based on a variety offindings that help piece together parts of a puzzle. There is no single,definitive test for FIP except via a brain biopsy after the cat has died ofFIP. On rare occasions, it can be diagnosed by an intestinal biopsy, but findinga positive result via this method is more hit-or-miss.

In most cases, weassemble pieces of a puzzle. The first two factors are those discussed earlier:the cat must have a history of coming from a multi-cat environment and have hada recent stress like surgery, moving to a new home or being introduced to othercats, or even a recent vaccination. Secondly, the cat often has weight loss ora failure to grow and a persistent fever for more than 4 days.

If your veterinariansuspects that your cat has feline FIP, tests include bloodwork including a fullchemistry panel and CBC, testing for FeLV, FIV, and toxoplasmosis, and running a FCoV titer.Your veterinarian will be looking for a number of factors in your cat'schemistry and CBC panels, including anemia, low white cells, and abnormalenzyme levels. A cat with FIP will also have a high FCoV titer.

It should be notedthat a high FCoV titer ALONE is not enough to support the diagnosis of feline FIP. Asdiscussed earlier, there are many different strands of FCoV, and this testcannot differentiate between strands. All it tells you is whether a cat has beenexposed to a coronavirus, not to whether she has been exposed to the feline enteric coronavirus AND not whether that strand hadmutated into FIP into a given cat. If all of these factors are not present, butsome are, there are additional specialized laboratory tests that can beconducted, including an alpha-1 glycoprotein test and protein electrophoresis.I highly recommend that any suspicion of FIP be further investigated with thesetests.

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Cats with the effusiveform of FIP can also have fluid drained from their abdomen or chest foranalysis at a lab. Additionally, there is a test calledthe Rivalta test that can be conducted on the fluid sample if your veterinarianis willing to do so, although the test itself is considered non-scientific. Formore information about this test, please see this website (opens in a newwindow).

The diagnosis of FIPis regrettably quite complicated, and it is important to request many, if notall, of these tests from your veterinarian. Unfortunately, feline infectiousperitonitis is often misdiagnosed, and I have heard of far too many cases wherea young cat with a fever has been given this death sentence with NO otherindications of having FIP. If your vet is not familiar with these protocols, Ihighly recommend visiting Dr. Addie's site, the world's expert in FIP from Glasglow, where you canprovide your vet with a flowchart for diagnosis and even worksheets to helpsupport your cat's diagnosis.

Noodles was tested forall of the above, was negative for toxoplasmosis and leukemia, but theresults of the feline FIP tests indicated he was positive. I was advisedto euthanize my little kitten. I was told I needed to euthanize him so that hewouldn't be around my other cats and infect them. At the time, FIP in cats wasthought to be highly contagious. Now,however, we understand that the virus needs to be shed in a cat's stool,ingested by feces to mouth of another cat, and then mutate within the new cat'sbody -- a process that doesn't make it as contagious as initially believed.That said, isolating a cat with FIP from other cats, especially the very youngor very old, is still advised.

FIP Treatment

gray and white cat with feline fip
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When I received thediagnosis for Noodles, I refused to believe that my only option was toeuthanize him, so I read everything I could get my hands on about catFIP, and even started calling veterinary schools around the country in anattempt to find out anything I could about fip treatment. I was desperate tofind someone who would tell me how to save my kitten's life.

One of the veterinary schools I called, the College ofVeterinary Medicine at Cornell University, was exceptionally helpful and Isuddenly found myself talking to Dr. Johnny Hoskins, whom I have since come toknow as one of the feline FIP experts of the world. I was so fortunate that a busy Cornell Professor with students tosupervise, classes to teach, journal articles to write, lectures and travelingto do would get on the phone with me, a nobody in the world of veterinarymedicine at the time, to talk about my kitten and Feline FIP.

In a nutshell, Dr.Hoskins confirmed that almost all cats with FIP die quickly, but also assured me that my other catshad already been exposed, so euthanizingNoodles to save them would not be the reason to do so. While it was a long shot, he let me know that therewas feline infectious peritonitis treatment I could try. A handful of cats hadsurvived FIP and I was determined to give my kitten, Noodles, the best chancepossible to become one of those cats.

The standard protocolfor treating cats with FIP is to give steroids by mouth and antibiotics to helpcontrol fever and/or prevent infections that can result from immunosuppressinga cat. In Noodles's case, because of his eye involvement, I also needed to givehim steroid drops in his eyes. On my own conviction at the time, I also startedNoodles on a Vitamin C powder supplement formulated for cats with viraldiseases.

Since that time,additional treatments have emerged as ways of helping to prolong the lifespanof infected cats. Among those treatment options are feline interferon omega(Virbagen) or less ideally human interferon alpha. Both of these medicationshave shown some success in curing or at least significantly prolonging thelifespan of cats with non-effusive FIP. Unfortunately, most treatmentsavailable today seem to have little affect on the effusive or wet FIP cases.

Cats with FIP todayare also often placed on a variety of vitamin supplements, including VitaminsA, B1, C, and E, as well as a B-complex vitamin.

Prognosis and Outcomes

For several months, Noodles received his steroids andVitamin C and chicken baby food, whichwas all he would eat. FIP in cats causes a decrease in appetite so it was difficultto get him to eat. He was quiet, notplayful like a kitten should be, but he ate, slept, cuddled and seemed content.Miraculously, over the next months, he slowly improved, his eyes cleared upcompletely and he had perfect vision and he began to play and eat better.

15 years later, Noodles had to be euthanized from an entirelyunrelated condition, after living 15 glorious years as my best feline friendever. There are those who will say he probably never had FelineFIP or he wouldn’t have lived. However, I feel strongly that he did especiallyafter going on to Veterinary School myself and practicing for over 20 years nowin my own feline only hospital. I have learned even more about FIP in cats andhave had numerous patients with the disease.

Since Noodles, I have diagnosed and treated and,unfortunately, euthanized many cats with Feline FIP. I have attended numerousseminars on FIP in cats and read every new bit of information that comes along.I have consulted further with the cat FIP experts of the world, including Dr.Hoskins, who saved Noodle’s life by giving me hope and suggesting andencouraging treatment when no one else would.

Several years later, when I had become a felineveterinarian, Dr Hoskins again guided me through another FIP case that went onto live to the ripe old age of 18. That cat had all the signs of FIP as well asall the positive test results AND had an intestinal biopsy that confirmed thepresence of the FIP-type lesion in the tissue. He was also treated with prednisoloneand slowly recovered.

That said, itis still quite rare for cats to recover from FIP. However,there are reports of more and more cats who have done so. Most survival stories are for those cats withthe dry form of the disease, but there are some indications that cats with eventhe wet form can overcome it. We have a long way to go before we have a cure,or even better treatments, but we are slowly moving forward.

You can hear more about research progress regarding FIP incats in our radio show discussion with Steve Dale:

Most recently, I have worked with another cat with effusive FIP. Hewas treated oral prednisolone, therecommended vitamins, antibiotics, and Feline Interferon. The felineinterferon is very expensive and had to be imported from Great Britain, butthis kitty's loving owner was determined to do everything possible to save hiscat's life. While he did exceed the length of time I originally thought hewould live, and the length of time anycat with effusive FIP is expected to live, he was still, sadly, one ofthe many victims of FIP.

Additional Resources

The following resources and discussions may prove helpful in your search for information about feline FIP:

You may also read the questions and answers below from readers who have had experiences with cat FIP.

Leave Feline FIP and return to the Feline Illnesses Index

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