As a breeder with 20 years of breeding experience, I asked myself this question for the first time in 2002. I had discussions with many breeders of other breeds and read many articles in magazines on the subject. In November 2020, I was unfortunately confronted with FIP for the first time in my breeder life. My future stud had developed Neuro FIP without eye involvement. For me as a responsible breeder, breeding with a FIP stud or cat is undoubtedly not an option.

So I dug out all the articles and magazines I had collected over the years and read them again, as well as reviewing all the information from my former breeder colleagues, and my opinion was confirmed once again.

An article that appeared in a cat magazine in 2004 (abbreviated by me):

FIP appears everywhere, in small cattery's, in large cattery's, in individual homes, as well as in families with 2-3 cats, etc. FIP is not only to be found in messy cattery's with dirty environment, but also unfortunately in well-kept homes and apartments where cats are spoiled, belong to the family, enjoy the balcony, garden or roam freely outdoors. 

Every breeder is afraid about this topic and is quite helpless and powerless when it comes to FIP. Almost no cattery is spared from FIP. Veterinarians confirming the increasing cases of diseases in breeders. Many free-roaming domestic cats also fall ill with FIP, but often die in the wild and can therefore not be specifically identified.

The FIP disease, which mainly occurs in young cats, causes more and more breeders to search for the root cause and that is a long and contradictory journey. More than 100 FIP cases in various cattery's domestically and abroad show a completely different picture than previously assumed.

For example: 16 kittens from three different mothers thrive in one "nest". They play, clean and eat together and "only two" of them (from the same mother) get FIP. All others kittens were and remain as fresh as a daisy! They shared a bowl, a water bowl, a blanket and also the litter box.
Another example: A queen had four litters. In the third litter she had 6 babies, of which two kittens suddenly fall ill with FIP. All other kittens in all her litters were and remained healthy.

There are countless such examples and they show one thing above all: the disease FIP is not contagious as this was always been assumed. The origin will likely be found in genetics.

This could also explain why FIP vaccinations are useless. In genetically healthy cats it has no effect, since the cats would have remained healthy without this precaution, and cats suffering from FIP it expedites the process of the disease. The FIP test costs only money and is useless, because FIP cannot be tested.

You can also disregard the stool collection and test, because you can only find corona viruses and not FIP. Detecting the coronavirus titer in the blood adds to the confusion, as many cats have a titer of 0 to 25 just before death. Over 90% of all cats have already had contact with corona virus positive cats.

It has been observed that the stronger the immune system is reacting, the more FIP spreads in the cat's body. Because the more macrophages want to remove the FIP foreign body, the more the organism will be damaged. This means in plain English that immune booster like "Baypamun" or the homeopathic form "Echinacea" are not allowed in cats suffering from or suspected of having FIP. Make sure that your cat is not given these substances.

Some time ago, the kittens were separated from their mothers at the age of 6 weeks to prevent "contamination". We know of a place where 12 kittens out of a total of 22 kittens died as a result of this method, despite being separated from their mother. All 12 kittens were from the same stud. This emotional drastic cure is irresponsible. If a cat has the genetic defect, it will sooner or later develop FIP. If it is not affected, it will not develop FIP, even under severe stress.

More than 100 of the analyzed FIP cases in the respective cattery's always stemmed from a very specific stud. For example, if there are three studs living in a cattery, it must be analyzed in the case of kittens suffering from FIP, which stud sired this litter. This stud will produce one or more kittens with almost all of the females he will mate (own and approved) that will develop FIP. This also explains why there are more and more cases of FIP outdoors or bred and "it seems this horror never ends".

Of course, these studs produce male and female kittens, which inherit the gene but show no symptoms and are later again used for breeding. (...and the horror of FIP doesn't stop). Those studs need to be neutered urgently, even if they are so valuable and beautiful! They spread unspeakable suffering for the breeder, who cares for the litter with love, for the subsequent buyer and above all for the suffering, affected cat.

It is quite possible that these cats do not develop FIP themselves and can enjoy a nice, long life as castrates. The queen to be mated will not get sick either, as FIP is not contagious. FIP does not have to break out in the first two years of life. The disease can also break out later in life under stress.

In some cases, the mother queens were most likely responsible for her FIP sick kittens, since the stud did not produce sick kittens with several other litters. The stud as a carrier of the disease represents a higher risk factor, because he passes on his genetic material more often than a queen. If both parents are affected, at least 80% of this litter will die of FIP.

According to the latest findings, it can be assumed that both parents need a genetic disposition in order to produce FIP-sick offspring!!

FIP comes from inside the cat. The genetic predisposition for the development of FIP was discovered in 1996 by Dr. Niels Pederson USA. He had examined breeding and health data over ten generations and several pedigree cat lines.

WHAT can breeders do? Breeders can and need to know and analyze the ancestry of their cats. Pedigrees need to be compared. In FIP cases, it must be clarified whether the queen or the male has the genetic disposition (or even both).

There are now a number of interesting and extensive websites about this topic, after in 2019 a field study was conducted by Dr. Pedersen with a drug called GS-441524, GS for short.

Since there is no specific FIP test, veterinarians evaluate the symptoms of the diseased cat, the diagnosis and rule out a differential diagnosis.

How is FIP diagnosed?

Until recently, FIP could only be confirmed by autopsy. Conclusive, well-defined tests for FIP have been available since 2019, although not all veterinarians are yet aware of advances in diagnostics.
If a FIP diagnosis is suspected, GS can also be used to find the diagnosis. GS treats only FIP; If the cat responds to the GS treatment and its condition improves, the diagnosis is confirmed.

Diagnosing Effusive ("wet") FIP

Effusive FIP is characterized by a build up of fluid in the cat’s abdomen (ascites), lungs (pleural effusion) or heart (pericardial effusion).  Cats who have ascites will often appear pot-bellied and their belly may feel like a water balloon.  If the effusion is in the heart or lungs, the cat may not have any outward changes in appearance.  If the fluid build up is severe, breathing may sound congested or be visibly labored.

Additional symptoms typically include inappetence, lethargy, high fever that does not respond to antibiotics, 3rd eyelid protrusion, and occasionally jaundice.

Complete CBC & Chemistry Panel

Whenever wet FIP is suspected, a complete blood panel and chemistry panel should be the first step toward a diagnosis.  The typical FIP blood work will show low albumin, high globulin, high white blood cell count, low red blood cell count, high neutrophils, high protein, and high bilirubin. Most FIP cats will have non-regenerative anemia, as well as a persistent fever.  Not all blood results will look the same; however, if some markers are present and the cat’s symptoms suggest a presumptive diagnosis of FIP, further diagnostics are generally recommended.

FIV/FELV Test

In that both FIV and FELV are more common and can present similar to FIP, these should be tested for and ruled out as a primary or secondary diagnosis.

RT-PCR of the effusion
Using a syringe, the veterinarian draws a sample of the fluid for testing.  This is a simple procedure that is done in the office, typically without the need for anesthesia or sedative. If FIP, the effusion is typically high in protein, straw or honey colored, and viscous.  Reverse transcriptase polymerase chain reaction (RT-PCR) detects the RNA of the FCoV – i.e. is a test which detects actual virus.   Quantitative RT-PCR (RT-qPCR) is an interesting recent development in which the amount of virus in the sample may be measured.  A positive RT-PCR on the fluid is a confirmed diagnosis of wet FIP.  A negative RT-PCR on fluid does not necessarily rule out FIP, as there is roughly a 30% chance of a false negative.  

DO NOT run a RT-PCR test on blood or feces.   RT-PCR on blood or feces can, and often does yield a false positive, or a false negative.

GS As A Diagnostic

In cases where FIP is the presumptive diagnosis, an alternative to extensive additional lab work or procedures is to use GS diagnostically.  GS441 does not treat or cure any condition other than FIP therefore, if the cat begins to respond after a few doses, FIP can be confirmed. If the cat does not have FIP, the GS will do no harm.

Diagnosing Non-Effusive ("Dry") with ocular and/or neurological involvement FIP

Dry FIP may present with a variety of symptoms, many of which are consistent with other conditions as well, which makes a diagnosis more difficult. Cats with dry FIP often present with lethargy, stunted growth,  inappetence, fever, anemia, and/or protruding third eyelid(s). There is often a history of diarrhea. 

If there is ocular involvement, uveitis, keratic precipitates - KP (keratic precipitate is an inflammatory cell deposit on the corneal endothelium), aqueous flare, or retinal vessel cuffing may be present.  

If the virus has affected the central nervous system or brain, neurological symptoms may include ataxia, tremors, seizures, or nystagmus (darting eyes).

Complete CBC & Chemistry Panel

Whenever dry FIP is suspected, a complete CBC and chemistry panel should be the first step toward a diagnosis. The typical FIP blood work will show low albumin, high globulin, high white blood cell count, low red blood cell count, high neutrophils, high protein, and high bilirubin. Most FIP cats will have non-regenerative anemia, as well as a persistent fever.  Not all blood results will look the same; however, if some markers are present and the cat’s symptoms suggest a presumptive diagnosis of FIP, further diagnostics are generally recommended.

However, more and more dry FIP cases are emerging in which the blood count does not show any of the above characteristics, but the symptoms are more than clear.

Ultrasound

Dry FIP causes lesions to whichever organs are affected by the virus. An ultrasound can reveal whether or not lesions are present, as well as check for enlarged mesenteric lymph node(s) and enlarged kidneys.  During the ultrasound, a fine needle aspiration of the lesions may be done in the office, and with typically no need for anesthesia.  Samples should be sent to a lab for immunostaining. 

Immunostaining

Direct staining of FCoVs within macrophages by immunofluorescence in cytocentrifuged effusions or immunohistochemistry in tissue is considered the most specific test to confirm FIP. Immunostaining cannot differentiate between the “harmless” FCoV and FIP-causing FCoV, but finding infected macrophages in characteristic pyogranulomatous lesions or in inflammatory effusions is highly associated with FIP. In a recent study in which a large number of cats with confirmed FIP and controls with other confirmed diseases were investigated, positive immunofluorescence staining of intracellular FCoV antigen in macrophages of the effusion was 100% predictive of FIP. Although immunostaining has a high positive predictive value, the negative predictive value is not high, which means that a positive result is likely to be a true positive, while a negative result may not be a true negative. Therefore, a negative result does not rule out a diagnosis of FIP. 

GS As A Diagnostic

In cases where FIP is the presumptive diagnosis, an alternative to extensive additional lab work or procedures is to use GS diagnostically.  GS441 does not treat or cure any condition other than FIP therefore, if the cat begins to respond after a few doses, FIP can be confirmed. If the cat does not have FIP, the GS will do no harm.

THERE IS NO "FIP TEST".

Proper diagnosis requires a variety of tests to both confirm FIP and rule out other diseases that share similar symptoms. What is sometimes (incorrectly) called the "FIP test" measures the cat's exposure to FCoV. 95 percent of the world's cats population have been exposed to FCoV. These titer tests are NOT conclusive. A positive titer for FCoV does NOT indicate that the cat has FIP.