Cat Guardians 101

How to diagnose FIP

FIP is a notoriously difficult condition to diagnose, many other conditions present with very similar clinical signs. Definitive diagnosis is often only possible at post-mortem. Because we can’t rely on any specific test for a diagnosis, we must combine the history, clinical signs, laboratory test results, FCoV tests results and possibly imaging to come to a “probable” diagnosis.

The tests commonly used are:
Chemistry panels
Complete blood count (CBC)
FCoV titer test on blood/serum with dilution 1:25 or ideally 1:10
FCoV RT-PCR on effusions
FCoV RT-PCR on fine needle aspirates
Rivalta test on effusions

If your cat is in good health, he or she DOES NOT HAVE FIP, no matter what the tests say and if you are not happy with the way your veterinarian is working on your cat’s case – look for a second opinion.
An effusion sample, NOT blood samples, should be sent to specialized laboratories for RT-PCR testing.
Blood samples should NEVER be sent for FCoV RT-PCR, even though some misinformed laboratories ask for blood samples for that test.
You can read more about testing in our FAQs page here.

At time of writing, the only way to be absolutely certain (100%) of an FIP diagnosis is to biopsy affected tissues and have them examined by a veterinary histopathologist. A biopsy, which is an invasive procedure, is often simply not an option in a severely sick cat, especially taking into consideration the procedure itself may hamper the cat’s outcome. However, in the cat who is already undergoing a laparotomy – or perhaps even a spaying operation – and if suspicious lesions are seen, a biopsy can be taken and sent to a reputable histopathology laboratory. A fine needle aspirate of the suspicious lesions should also be taken and stored in the fridge for FCoV RT-PCR testing should the biopsy come back as inconclusive, or suspicious of FIP.

Dr. Diane Addie has developed a FIP diagnosis algorithm  in which she recommends RT-PCR testing of the effusion or an organ sample drawn by a needle as diagnostic technique preferable to biopsy. Worth to note, only 18% of samples sent to her laboratory for non-effusive FIP diagnosis actually turn out to be FIP. Since cats with FIP are usually euthanized, it is absolutely vital that FIP is accurately differentiated from other, treatable, conditions.

Issues with Testing
FIP is so difficult to diagnose because it can cause almost any clinical signs you care to imagine and to date, there is NO specific test for FIP. FIP presents a challenge for even the best veterinarians because it appears like a number of other diseases, including heart failure, liver disease, pancreatitis, toxoplasmosis, cancer, etc. Even some relatively benign conditions can mimic FIP (i.e., pregnancy, weight gain). YOU are the one paying for your cat’s laboratory tests so please make sure your veterinarian is using a reputable laboratory; otherwise your cat’s laboratory results could be meaningless. Also, insist your veterinarian sends the best samples for getting an accurate diagnosis.

Treating FIP

Sadly, at time of writing, there is no cure for FIP, and before embarking on any treatment, you MUST be absolutely certain the cat has FIP. Your veterinarian will make some recommendations to either make your cat comfortable or suggest a course of treatment to attempt to prolong your cat’s life by managing the condition. While there are several cases worldwide of cats still alive after several months or even years of confirmed diagnosis, the overall prognosis for an FIP cat is poor, and at this point the stage of contagion has passed thus it is not necessary to quarantine the cat from the rest of the household’s feline members.

You can provide the sick cat supportive care which will make him/her more comfortable and possibly extend his/her life as long as the quality of life remains. The dry form of FIP progresses more slowly, and cats with this form of the disease tend to live longer than those with the wet form. This is especially true if the only organ affected is the eye. In addition, cats who still have an appetite, no anemia and no neurological signs usually respond much better to treatments.

It is beyond the scope of this website to specifically address treatments and protocols available to treat a cat with FIP.  You can find advice and support in this difficult time by joining the FIP Advisory and Care group on Facebook.

Vaccination against FIP

At time of writing, there is only one licensed FIP vaccine available. Felocell FIP® (formerly called Primucell® FIP), produced by Zoetis (formerly Pfizer Animal Health) and available since 1991 but not in all countries. Felocell® FIP is a temperature-sensitive, modified-live virus vaccine developed based on the intranasal administration of an FCoV isolate that only replicates in the tissues of the upper respiratory tract and is designed to provoke a good local immune response. The vaccine appears to be safe; however, many questions have been raised over its efficacy with different studies providing very different results. Field studies have reported efficacy and safety, infections of laboratory cats have not been favorable. The use of this vaccine is probably one of the most controversial areas in any discussion of FIP. It appears that the vaccine may have efficacy in some situations, but that it provides considerably less than 100% protection. In addition, the vaccine is currently only licensed for use in kittens over 16 weeks of age, and in endemic situations most kittens of this age will already be infected with FCoV.

Nevertheless there are some situations in which the vaccine may be of value – if kittens have been reared under conditions to prevent exposure to FCoV, they could be vaccinated prior to introduction to a high-risk environment, and similarly if other seronegative (or low titer) cats are being introduced to a high-risk environment, for example a boarding cattery or rescue shelter, these too may benefit from vaccination. To be clear, if you have a cat who hasn’t been exposed to FCoV and you vaccinate him/her, you increase that cat’s chance of surviving an encounter with coronavirus. It’s not 100% protective but it is certainly better than nothing.

Felocell® FIP is not generally recommended by the American Association of Feline Practitioners Feline Vaccine Advisory Panel. Cat owners should consult their veterinarian to help them decide if their cat should be vaccinated

What is Feline Infectious Peritonitis?
What causes Feline Infectious Peritonitis?

What cats are at risk of developing FIP?
What are the clinical signs of FIP?

What can you do to prevent FIP?
Grieving for the loss of your  FIP cat

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