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Winn Report on Fip

FIP Q&A

by Amy Jackson 

Revised by Anna-Lena Berg, DVM, on January  3, 2017

(Based on reputable research, peer reviewed literature and personal opinion from my experiences.)


My cat tested positive for antibodies against the FIP virus. Does this mean he/she will get FIP?
Most likely, no. Let me say the name of this test should be changed from FIP virus to FCoV (feline coronavirus) antibody test. FIP is the name of the disease. FCoV (sometimes called FECV = feline enteric coronavirus) is the virus causing FIP, but only after it has mutated to the dangerous variant designated FIPV (FIP virus). The antibody tests don’t distinguish between harmless, non-mutated FCoV and FIPV. A seropositive titer test result just means your cat has been exposed to FCoV. It has no predictive value of FIP.

What antibody test should I do? FCoV, FECV or FIPV, I'm confused?
All are antibody tests that detect antibodies to FCoV. They are one in the same.

My vet told me about a specialized antibody test called 7b ELISA protein test for FIP. Should I do it?
My opinion is it provides useless information. It was originally thought that only mutated FIPV produced the 7b protein, and that antibodies against 7b were FIPV specific. Later it has been discovered that both non-mutated FCoV and FIPV produce the 7b protein, and evoke antibodies against it. The 7b ELISA has no value in diagnosing FIP or predicting the development of FIP. All it means is that your cat has been exposed to FCoV.

So give me some statistics on the occurrence of FIP.
Studies show that a large proportion (90 -100%) of shelter or rescue cats have been exposed to FCoV, yet approximately only 5 to 10% ever develop the disease FIP. Similarly, FCoV is very common among purebred cats in catteries. There are more virulent strains of the virus and sometimes you will see outbreaks in a shelter or cat hoarding situation. This is most likely due to living in close quarters, sanitation issues, constant stress on a cat's immune system because they don't have their own space or may not get along with other cats. It is also an uphill battle of fighting off respiratory and parasitic infections in shelter living.

Looking at the feral population of cats 50% - 60% have also been exposed to FCoV. It is estimated that between 2% - 5% of ferals exposed will develop FIP. More likely ferals will die from exposure to the elements, poisonings, being hit by a car, malnutrition or lack of medical care.

My cat tested positive for antibodies against the FIP virus, should I separate this cat from my other cats? Should she be in a household with only one cat? I'm ready to give her away.
Remember the confusion about the test name? This only means your cat has been exposed to the virus. There is no reason to separate your cats. The majority of cats have already been exposed to FCoV in the shelter, rescue or cattery where you got your cat from. They are probably already FCoV positive if they have come from a shelter or a cattery. FCoV is shed in the feces of infected cats and is transmitted to other cats by feces to mouth spread (for instance via contaminated food plates).

How do I know if my cat is shedding the virus?
1 out of 3 cats exposed to FCoV will be chronic shedders of the virus. The remaining 2 out of 3 cats will be intermittent shedders or completely clear themselves of the virus. You can test for FCoV shedding by a RT-PCR test from a fecal sample. If you get a positive result, you know your cat is currently shedding the virus. If you get a negative result, this means your cat is not shedding the virus at that moment. A negative test result does not necessarily mean your cat has cleared itself of the virus. To be certain your cat is not an intermittent shedder, it is recommended that you test monthly for 5 consecutive months. If all 5 tests are negative, you can almost be certain your cat is not a shedder of the virus. Keep in mind this does not rule out cases of reinfections.

What cats are most at risk for developing FIP?
The highest risk categories are kittens and young cats under the age of 2, those that are immune compromised such as cats with FeLV and FIV, and older cats (> 12 years). Adult cats between 2-11 years of age are less likely to develop FIP, although cases may occur at all ages. It is believed that immune system, health, and stress all play a contributing role in the development of FIP. Until around the age of 4 months, kittens are still being covered by their mother's immunity. It is after this 4 - 6 month period up until around 1.5 - 2 years old that cats will be developing their own immunity to viruses, parasites, and other harmful things in the environment. This is why kittens and young cats are the ones most vulnerable to FIP. Genetics also plays an important role in the development of FIP. Research is currently being conducted to see if certain breeds are more likely to develop FIP than others, and what genes are involved in the resistance against FIP.

So how do I prevent infections or reinfections of FCoV?
Practice good litter box hygiene. This means scooping fecal material as soon as you become aware of it. Remove stray litter that may have been tracked or kicked out of the box. Clean up fecal smears on the sides and edges of the litter box. Clean out the whole litter box once a week, using dish soap and disinfectant. If you have more than one cat, provide several litter boxes (preferably one litter box per cat, plus one, if smaller boxes are used). Don’t put litter boxes close to where your cats eat or drink.  

What happens when the virus mutates? I thought it was contagious?
Non-mutated FCoV lives in the gastrointestinal tract and is harmless. In a certain percentage of cats infected with FCoV, the virus mutates within their bodies, causing the harmless intestinal infection to develop into the deadly disease FIP. When the virus mutates, it moves out of the gastrointestinal tract into macrophages (a type of white blood cells).  The infected macrophages circulate into the blood and spread the infection to various organs in the body. The mutated FIPV doesn’t remain in the intestine, and isn’t shed at all, or in negligible amounts, in feces. Thus a cat with FIP is not contagious to others and it is not necessary to isolate your cat that has been diagnosed with FIP.

What can I do to prevent the mutation of the virus that causes the disease FIP?
Preventing FCoV from mutating into the disease of FIP is beyond our control, but you can do things to minimize contributing factors. Keep stress levels low. This means allowing your cat enough personal space to hide from visitors and other cats in the house. Provide secluded hiding spaces with more than one way in and one way out. It is said a single cat needs approximately 500 sq. ft. per cat which includes vertical space. If you have a "bully" cat in the household try Feliway, Bach Flowers Rescue Remedy for Pets, or Thundercoats to try and maintain a harmonious household.


Treat any other illnesses or infections your cat may have. This means getting antibiotics for an upper respiratory infection that fails to clear itself. If your cat goes outdoors, it is most likely to pick up parasites from the yard. Worms, fleas, and protozoa infections need to be treated as they can cause many other health problems that stress your cat's immune system.


Provide decent nutrition. Cats are obligate carnivores. I am a strong believer in feeding cats wet food with most of their diet consisting of animal protein and very low carbs or no grains. Cats are not big water drinkers like dogs. Dry food leaves cats dehydrated. Dry foods have much of their nutrient content destroyed or altered by the heating and processing of dry kibble. Chemists try to fix this deficit by adding back in synthetic supplements. Dry foods tend to be higher in carbohydrates which will eventually lead to obesity, diabetes, IBD, and/or kidney disease. Dry foods contain more plant based protein versus animal based protein. For more on nutrition I recommend this web site written by a veterinarian nutritionist. http://www.catinfo.org

My vet diagnosed my cat with FIP and said I should put him to sleep. What should I do?
It depends on what stage of the disease your cat is in, and how much knowledge your vet has about FIP. If your cat is very ill, not eating or enjoying life anymore, and the diagnosis of FIP is clear, your vet may be right to advise you to put him to sleep.  However, many vets know little about FIP because it is not frequently seen in their daily clinical practice. Sometimes a diagnosis of FIP is made without taking potential differential diagnoses into enough consideration. Make sure you have a good dialogue with your vet and ask him/her to explain and show you the test results and other findings that made the vet diagnose FIP in your cat.

Vets who don’t see many cases of FIP in their practice may not be aware of recent advances in medical treatment and palliative care for cats with FIP. Some medications such as prednisolone, polyprenyl immunostimulant (PI), feline omega interferon (FOI), and supplementing with vitamins and antioxidants, have been shown to improve the length and quality of life for cats with FIP. In short, giving us more precious time with our FIP baby.

If your vet doesn’t seem to be aware of these treatment options, please encourage your vet to visit Dr. Addie's web site. She is a leading and well known FIP researcher, and her web site contains valuable information both concerning diagnostics and treatment options:
http://www.dr-addie.com

 
 

Diagnostic tests for FIP


By Anna-Lena Berg, DVM, PhD


Introduction

The diagnosis of FIP is not based on a single test. First of all, the cat’s age, history, clinical signs and the results of the physical examination by the vet must be considered. Already at this stage FIP may be suspected, although various differential diagnoses remain in the picture. Blood tests such as a complete blood count (CBC) and blood chemistry profile provide important basic information that will either strengthen or weaken the suspicion of FIP. Ultrasonography and effusion analysis will further help establish or refute a diagnosis of FIP. The vet is looking at the sum of several findings to arrive at a correct diagnosis, which can be tricky, especially in cases of dry FIP.

Definitive diagnosis of FIP

The gold standard of diagnosing FIP is via necropsy and subsequent histopathological examination of tissues. The lesions and inflammatory reaction in organs caused by the FIP virus are very characteristic, and – especially in conjunction with immunohisto-chemistry to demonstrate the presence of virus in tissues – sufficient to establish a certain diagnosis of FIP. The problem, of course, is that this method can only be used when the cat is dead.

In a living cat with dry FIP, a biopsy from a mesenteric lymph node or other internal organ showing typical FIP pathology (granuloma), together with immunohistochemistry, carries the same diagnostic weight as a complete post mortem examination. The problem is that a full biopsy (not a fine needle aspirate) is needed, and this requires that the cat is under anesthesia and is strong enough to tolerate surgery.  Since many cats with dry FIP, at least in the more advanced stages, are too weak for such procedures, it is rather unusual to diagnose FIP in this way.

In a living cat with suspected wet FIP, a positive RT-PCR test or immunostaining for the presence of virus (see further below) on a sample of the fluid in the abdominal and/or chest cavities or in a sample of cerebral spinal fluid is considered accurate for a certain diagnosis of FIP. A negative test, however, doesn’t completely exclude FIP.


Findings on the CBC and blood chemistry panel commonly associated with FIP

Several abnormalities are seen in cats with FIP, although it must be emphasized that not all cats with FIP will show the expected changes in every parameter. The list below is not complete, but presents the most common findings:

  1. Elevations in total protein and gamma globulins - Cats with FIP often have high serum protein levels. The main types of proteins in the blood are albumin and globulin. In FIP it is the globulin fraction that is increased, while the albumin fraction is either within normal or slightly lower than normal range. Globulins can be further analyzed by serum electrophoresis, a method that separates sub fractions of globulins. In cats with FIP or other chronic inflammatory diseases, it is the gamma globulin fraction that is increased, showing a characteristic peak.

 

  1. Albumin to globulin ratio - A low albumin:globulin ratio (< 0.8, usually < 0.6) is often associated with FIP. It is important to look at the albumin and globulin values to understand why the ratio is low. In FIP, the ratio becomes low due to the increased globulin level. However, a low albumin:globulin ratio can also be seen if albumin is lost, for instance through protein-losing enteropathy, or if it is insufficiently produced by a diseased liver. It should be noticed that a low albumin:globulin ratio, even if it is low due to increased globulins, is not a finding specific for FIP. Any chronic inflammation in the body can produce the same alteration of the ratio.

 

  1. Hematology changes and bilirubin - In the red blood cell (erythrocyte) panel the following changes are commonly seen in FIP: low hematocrit, low hemoglobin, low red blood cell (RBC) count, and low mean red blood cell volume (MCV). This means that the cat has anemia due to increased destruction of erythrocytes. In anemia, the bone marrow responds by producing more red blood cells, so-called reticulocytes (immature erythrocytes). If the bone marrow response is insufficient, that is, too few reticulocytes are being produced, the anemia is said to be non-regenerative. This is the form of anemia usually seen in FIP.

    Bilirubin is often elevated in cats with FIP. This is due to the increased destruction of red blood cells; bilirubin being the degradation product of hemoglobin. Bilirubin can also be increased in liver disease

    The white blood cell panel often shows abnormalities in FIP: increased white blood cell (WBC) count, an absolute increase in neutrophils, and a decrease in lymphocytes. Low lymphocyte count (lymphopenia) is more common in wet than in dry FIP.  

 

Here is an example of how a CBC and blood chemistry panel may look like in a case of FIP*:
 

*Note: as can be seen here, not all parameters listed above are outside normal range in this case


Alpha-1-acid glycoprotein (AGP) and serum amyloid A (SAA)

AGP is a so-called acute phase protein that can be detected in serum. In FIP, AGP levels are usually greater than 1500 mcg/ml. In normal cats, it is up to 500 mcg/ml. It should be noticed that AGP will also rise in other infectious and inflammatory conditions such as bacterial peritonitis, pyelonephritis or fungal infections. In cardiomyopathy, non-infectious liver disease and tumours, which are conditions that can be mistaken for FIP, the AGP is normal. Serum amyloid A (SAA) is another acute phase protein in serum that has been found to be elevated in FIP. It is not yet commonly used in FIP diagnostics.

Feline coronavirus (FCoV) antibody titer

his test is often included on a feline blood panel and reflects a cat’s circulating antibody level against FCoV. The problem is that exposure to FCoV is common in cats and many perfectly healthy cats have antibodies against this virus. Another problem is that the test cannot distinguish between antibodies against the harmless enteric form of FCoV (sometimes called FECV) versus the mutated FIP virus (FIPV). Therefore an FCoV antibody test will only tell you whether a cat has been exposed to the virus or not. It can never on its own be used to diagnose FIP, although very high titers (> 1:3200) are more often associated with FIP than low ones (< 1:400).  In rare instances, cats with FIP may not be producing FCoV antibodies and have negative titers.

Analysis of effusions

The fluid that builds up in the wet form of FIP is called ascites when it occurs in the abdomen, and pleural effusion when it occurs in the thorax. The fluid is sticky and light yellow in colour, due to the presence of bilirubin. The total protein level in the fluid is usually greater than 3.5 mg/dl. Most FIP effusions contain a mixture of macrophages and neutrophils, with a low proportion of lymphocytes. The neutrophils show intact morphology in the microscope, in contrast to their appearance in bacterial peritonitis/pleuritis, where they often show degenerative (toxic) changes.  Effusions caused by bacterial infections are usually reddish/brown in colour, and not light yellow.


 

 

 

 

 

Typical effusion in FIP from http://www.lbah.com/word/feline/feline-infectious-peritonitis-fip/)

Rivalta test

This is a simple test to perform, and can be helpful in the diagnosis of wet FIP.  A test tube is filled with distilled water and one drop of 98% acetic acid is added. To this mixture one drop of fluid from the cat’s abdominal or chest cavity is added. If the drop dissipates and the solution becomes clear, the test is negative. If the drop retains its shape, stays attached to the surface, or slowly floats down to the bottom of the tube, the test is positive. In a study from 2012, involving almost 500 cats with effusions (not only FIP but also other diagnoses), a negative Rivalta’s test was found to be 93% accurate in ruling out FIP. A positive test was 58% accurate in ruling in FIP.

Here is a link to a short YouTube video showing how the Rivalta test is done (it’s in Italian; PIF stands for FIP): https://www.youtube.com/watch?v=vH96B8kJKgA

PCR tests

Polymerase chain reaction (PCR) is a highly sensitive technique that enables the detection of even small amounts of virus in a tissue or fluid sample. Since the viral genome of FCoV consists of RNA, the first step is to convert viral RNA to DNA (or more specifically cDNA; c standing for complementary), because RNA is too unstable to be analyzed. This conversion is performed by an enzyme called reverse transcriptase (RT), and that is why the test is often called RT-PCR.

The next step is to perform the PCR procedure itself, which means amplifying a part of the viral genome, getting multiple copies. This procedure used to be done in a PCR machine, whereupon the test tube was taken out of the machine and a sample from it run on an agarose gel, being identified as a band on the gel after staining it with a dye. Nowadays, another type of technique is used, so-called real-time PCR. It's the same basic principle, the main difference being that the PCR machine takes care of everything and no gel is needed.

Several laboratories offer PCR tests for detection of FCoV. One of these laboratories, IDEXX, has set up a real-time PCR test using a 2-step procedure: first a PCR for FCoV, then another PCR for biotyping. In the first step, the presence of FCoV is tested. If this test is negative, the second step is not run. If the first PCR shows the presence of FCoV in a test sample (fluid or tissue), the second PCR is run. This PCR is designed to detect the mutated form of FCoV, the FIPV. So, while a positive result in the first step PCR simply means the presence of FCoV, which could be either the harmless enteric form FECV or the deadly FIPV, the second step PCR specifies which of these variants that is present in the cat. The results of the IDEXX PCR procedures are described further in the box below (from: https://www.idexx.com/files/small-animal-health/products-and-services/reference-laboratories/feline-infectious-peritonitis-virus.pdf

FCoV biotype result

Interpretation

FIPV

FCoV has mutated into the FIPV biotype. In a cat with clinical signs this supports the diagnosis of FIP. If clinical signs are absent, the FIPV biotype indicates the cat is at high risk for developing FIP and should be monitored closely.

FECV

FCoV has not mutated and the cat is unlikely to have FIP.

Indeterminate

FCoV cannot be typed due to the occurrence of unknown strain variation. FIP cannot be ruled out.

Below limit of detection

FCoV cannot be typed because there were insufficient viral particles to permit biotyping. FIP cannot be ruled out. This result is common with whole blood specimens but can occur with any specimen type. Consider submitting an alternate specimen type.

Immunofluorescent FCoV staining of effusion

In this test the effusive fluid is tested on slides for the presence of FCoV, using antibodies tagged with fluorescent dyes. It is a simple procedure with high diagnostic sensitivity, provided that appropriate reagents and procedures are applied. For some reason it is not commonly used.

Flow chart for help with diagnosis

You may want to show your vet this flowchart written by Dr. Addie, a well-known FIP researcher. It is a helpful tool to aid in the diagnosis of FIP or to rule it out: http://www.catvirus.com/downloads/FIPdiagnosisflowchart.pdf

Further reading

Riemer F, Kuehner KA, Ritz S et al (2016). Clinical and laboratory features of cats with feline infectious peritonitis – a retrospective study of 231 confirmed cases (2000-2010). Journal of Feline Medicine and Surgery, 18:348-356.

Pedersen, NC (2014). An update on feline infectious peritonitis: diagnostics and therapeutics. The Veterinary Journal, 201:133-141.

FIP Treatment

 

From Niels Pedersen- BS, DVM, PhD

Center for Companion Animal Health, University of California - Davis
Professor Emeritus
Medicine & Epidemiology

Symptomatic treatment 

There is currently no effective treatment that is legally available for cats with confirmed FIP. Until new treatments can be approved and marketed, treatment remains largely symptomatic. A low to moderate dosage of prednisolone or prednisone (starting at 2 mg/kg, orally, once a day for two weeks and then 0.5-1 mg/kg indefinitely), coupled with a diet high in animal protein (e.g., 1/2 cooked chicken, turkey or rabbit and 1/2 a favorite commercial cat food) and a lot of personal care, is the simplest and possibly most effective symptomatic treatment. Symptomatic treatment ultimately depends on the cat's immune system to cure the infection. Some cats may have mild or subclinical disease isolated to a single intestinal lymph node, which may be detected as an abdominal mass upon routine physical examination or during a spay operation. Cats with more severe clinical signs will often go into a more chronic and less severe stage of disease after several weeks. As we gain more experience with treating rather than euthanizing cats when FIP is diagnosed, we begin to appreciate that a proportion of cats may survive for many weeks, months, and rarely a year or more. However, it is still fair to say that FIP is ultimately fatal to most cats if left to run its natural course. 

 

There are misconceptions on the value of removing fluid effusions. Cats with chest involvement and breathing difficulties can benefit greatly by removal of pleural fluid. Chest fluid also tends to be slowly replaced, especially when cats are treated with prednisolone. Removal of abdominal fluid should be discouraged unless it is so massive that it interferes with breathing. Abdominal effusions tend to be rapidly replaced at the expense of body fluids and proteins. Owners can be encouraged to maintain symptomatic and palliative treatment for as long as weight and activity are maintained. This can be days, weeks, sometimes months, and rarely a year or more. However, owners should be apprised of the extremely high morality that occurs among cats with clinically active FIP. 

There is some debate on whether certain non-steroidal anti-inflammatory drugs (e.g., TNF-alpha blockers such as pentoxifylline, thalidomide), specific immunomodulators (e.g., feline interferon omega, human recombinant alpha or beta interferon), and non-specific immunostimulants (e.g., several plant- or microbial-based biologics) have any efficacy against FIP. Although an initial study with feline interferon omega indicated efficacy, a subsequent large double blind and placebo-controlled trial showed it to be without efficacy. Human alpha and beta interferon are also of doubtless benefit and are immunogenic to cats and will be ultimately destroyed by the resulting antibodies. A similar large-scale trial with pentoxifylline also showed it to be non-effective against FIP. 

Homeopathic treatments for FIP 

Homeopathy involves the administration of sub-toxic doses of substances, usually plant based, which mimic the disease signs that are intended to be cured. There are several web sites that are offering various homeopathic medications for cats with FIP. They are basically dilute tinctures of various plant extracts. These extracts are quite expensive, and many desperate owners will be tempted to use them. One of these companies is in Australia -(http://www.naturalpaws.com.au/feline-infectious-peritonitis-fip-usefulinfo-112-false.html). 

Non-specific immunostimulants 

The use of non-specific immunostimulants has been popular in veterinary medicine for decades, usually for treating specific signs of feline leukemia and feline immunodeficiency virus infection such as anemia or low lymphocyte counts. There are occasional anecdotal reports of cats with “FIP” being cured or their lives prolonged by such treatments. These types of immunostimulants include substances such as Staphylococcal A protein, ImmunoRegulin (Propriobacterium acnes), Acemannan (mucopolysaccharide extract of Aloe vera leaves) and Imulan (lymphocyte T-cell immunomodulator). There is no evidence that these biologics have any beneficial effect on actual cases of FIP. 

 

Peritan FP is a plant-based substance that is advertised for cats with FIP. Itt can be found at - http://www.greenpetdepot.com/products/peritan. Interestingly, advertised statements about the efficacy of Peritan for FIP conclude with the following statement – “These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.” People should also be aware that some of the anecdotes attesting to the efficacy of a certain product for FIP are deliberately posted. Furthermore, many of the cats described may never have had FIP in the first place. 

The most popular non-specific immunostimulant touted on the web to treat cats with dry FIP is an extract of tree leaves. Polyprenyl immunostimulant (PI) (https://vetimmune.com/pi-product-information/) is classed as a biologic by the USDA and is manufactured by Vetimmune (https://vetimmune.com/) (formally Sass and Sass, Inc.). PI has been given a conditional license by the USDA as therapeutic for “symptoms” of feline herpes virus infection. Although not currently approved for the treatment of FIP by the USDA, it is being widely used off label for prolonging the life of cats with milder forms of FIP. Polyprenyl immunostimulant as a potential treatment for cats with FIP has an interesting history that extends from Russia to the United States. The research and chemical structure of PI is based on a biologic "plant extract" called Phosprenyl, which is used in Russia to treat a wide range of viral infections in many animal species (http://www.2ndchance.info/fip-gamavite.pdf. The first publication on the use of PI for FIP outside of Russia was an article (http://www.vet.utk.edu/research/fip/FIPpolyprenyl.pdf) published by Dr. Al Legendre and colleagues. In this study, three cats with subclinical dry form FIP were treated with Polyprenyl Immunostimulant. Two of the three cats were alive and well 2 years after diagnosis. The results from these three cats were used to justify a much larger treatment trial on 58 cats presenting solely with dry FIP. The results of this study were presented in 2012 at the ACVIM forum. Twenty-two percent were alive at least 165 days and three cats lived longer than 365 days (5%), which was longer than what was expected. However, this study was faulted for not including a placebo control group and was subsequently published in more detail and including a historical control group - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5306384/. This report described 60 PI treated cats with dry FIP and 59 cats with similar dry FIP from the literature that had not been treated. Eight of the 60 cats survived over 200 days, and 4 of 60 survived over 300 days No historical control cat that suffered solely from dry FIP and not treated with PI lived longer than 200 days. The conclusion was that PI treatment prolonged the life of cats with the dry form of FIP. 

The published results with PI are difficult to interpret, but it can be safely concluded from the researchers words that cats with wet FIP are not responsive to treatment and that there may be a small increase in survival time for cats with the milder dry form of FIP. It is also important to note that the USDA has not added FIP to its list of approved diseases for PI treatment and that the makers of PI do not promote its use for FIP. However, it has gained a vocal following on the web that generates a considerable market for treating FIP. PI may cost over $400 a month if used on an average size cat and dosed accordingly and this expense can be magnified by associated veterinary expenses. 

Non-specific anti-viral drugs 

Common drugs such as cyclosporine, cholesterol inhibitors such as itraconazole, various antibiotics, and several herbal extracts inhibit FIP virus in cell-culture, but the anti-viral effect is weak and potential toxicity great. These substances have their biologic effects by inhibiting normal metabolic processes of cells and some of these processes are usurped by viruses to aid their own replication. The amount of drug required to achieve the needed level of virus inhibition would be toxic or damaging to the cells and thus to the host cat. 

Targeted anti-viral drug therapy 

The current hope for treatment of FIP rests with several of the same types of specific anti-viral drugs that have been used to treat viral infections of humans such as hepatitis C and HIV/AIDS. These are small molecules that are readily absorbed into cells and specifically target viral proteins that are essential for virus replication. Their toxicity for non-viral processes (i.e., cellular functions) is extremely low, making them both safe and efficacious. We have described our laboratory and field experiences with GC376, a viral protease inhibitor, in an article in the Journal of Feline Medicine and Surgery. An abstract of this article can be accessed at the PubMed website (https://www.ncbi.nlm.nih.gov/pubmed/28901812). The rights for GC376 have been obtained by Anivive and they are starting the lengthy process of obtaining FDA approval for treating cats with FIP and eventual marketing - https://www.k-state.edu/media/newsreleases/2018-09/fipantiviral92018.html

We published our initial research studies on a second compound (nucleoside analog GS-441524- Gilead Sciences, Inc.) in 2018 and these results can be found at the Veterinary Microbiology journal open access article website - (https://www.sciencedirect.com/science/article/pii/S0378113518301603). The successful testing of GS-441524 in owned cats with a variety of forms of naturally-occurring FIP has just appeared in the Journal of Feline Medicine and Surgery - https://journals.sagepub.com/doi/full/10.1177/1098612X19825701. Similar reports will be forthcoming as other drugs go through experimental and field testing. We are convinced based on our research that anti-viral drugs of the type currently used for HIV/AIDS and hepatitis C virus (HCV) infection, and in test phase for Ebola, Marburg, MERS, SARS, and bat coronavirus infections will provide the best chance for curing this terrible disease of cats. These drugs include protease inhibitors, nucleoside analogs, RNA polymerase inhibitors, as well as other classes of anti-viral drugs that might target specific aspects of RNA virus replication. 

Unfortunately, the research phase for these drugs has ended and no more field trials are contemplated at this time and no drug is legally available for veterinarians or owners. The processes involved in getting these new drugs FDA approved and commercialized is long and it may be 2-5 years before these, or similar drugs find their way to veterinarians for use in the treatment of cats with FIP. This delay has created a vigorous and growing black-market for drugs like GC376 and GS-441524. GC376 is being illegally produced in China and sold through subsidiaries in Europe and US. GS-441524 is also being produced illegally in China but has not yet appeared on the market. Manufacturers and secondary suppliers state that these drugs are to be used for research purposes only and not for use veterinary or human applications but are well-aware of their great demand and willingness of many cat owners to pay an extremely high price for them. We have no idea of the purity or biological activity of these black-market compounds and veterinarians have no experience with preparing them for treatment or using them to treat cats with FIP. The treatment period for naturally occurring FIP is a minimum of 12 weeks, not the two weeks based on treating cats with experimental FIP. Many owners have spent thousands of dollars on black-market drugs and have had to stop treatment before this time, even though their cats are responding, due to the cost. The FIP will relapse if treatment is stopped too soon. Owners and veterinarians using should be also aware of possible legal and ethical consequences arising from the use of black-market drugs.