What is Feline Infectious Peritonitis (FIP)?

Feline infectious peritonitis (FIP) is a viral disease caused by feline coronavirus. Usually, this type of feline coronavirus causes mild diarrhea that doesn’t need treatment and it affects cats of all ages but it is more frequent in cats under 2 years and those older than 10. In some cases, this feline coronavirus may cause a more aggressive type of virus, FIP. This mutation may occur due to genetic predisposition, poor immune response, an unfavorable environment or because kittens have recently been through a stressful situation like being vaccinated, spayed or neutered, being introduced to new cats in their houses, or moving.

Is FIP contagious?

FIP is not contagious. Feline coronavirus is transmitted among cats by being in contact with an infected cat’s feces. However, it is assumed that most cats carry the virus or have been exposed to feline coronavirus. The FIP mutation is not contagious, and it is particular to every cat.

Manifestation of the Disease:

FIP is manifested in three main forms:

  1. Wet form: There is presence of abdominal and chest effusions, causing trouble breathing and an enlarged abdomen, general discomfort and anorexia. Through aspiration, it can be confirmed that the fluid is usually viscous and yellow, containing a high level of protein.
  2. Dry form: Its diagnosis is very challenging. It causes inflammation and pyogranulomas in different organs, causing a general failure of multiple organs, and it also shows ocular and neurological signs.
  3. Mixed form: A combination of both forms.

There are also other common signs of FIP such as fever, weight loss, yellow-tinged mucus, anemia, elevated protein count, high levels of globulin, and an A:G ratio below 0.4.

Diagnosis and Challenges:

There is not a specific way to detect FIP. There is no test that can be positive or negative for FIP. Therefore, the diagnosis is made by exclusion: ruling out other diseases such as feline immunodeficiency virus (FIV), feline leukemia virus (FeLV), toxoplasmosis, heart disease and hepatic disease, among others.

We insist that there is no serological or PCR test for feline infectious peritonitis.

Treatment and Management:

Yes, FIP does have a cure!

Thanks to Dr. Pedersen and scientific improvements, a specific antiviral drug has been discovered: GS-441524. This drug can inhibit viral replication and cure the disease.

This treatment has a cure rate over 90%, and it should always be administered by a professional veterinarian who follows the cat’s case closely. The treatment period is 84 days, during which the antiviral drug is administered orally (capsules or tablets) or subcutaneously (injections) every 24 hours. Both presentations of the drug are equally efficient, the choice of oral or subcutaneous administration is based on the cat’s overall health. If the cat’s health is too deteriorated, subcutaneous administration is recommended to guarantee that the drug is properly absorbed.

Decisions to start the treatment have to be made quickly while tests are still being run to exclude other diseases. It must be considered that treatment is also a powerful diagnostic tool, given that some improvement during the first days of treatment would confirm the presence of the disease.

There are other essential measures during the treatment:

  1. Weekly weight check. The same day of every week, weight must be checked and the milliliters of administered drug has to be changed in order to keep the same starting dosage. Remember that dosage and injected milliliters are not the same thing!
  2. Complete blood count, ultrasound, and regular examination on the 30th, 60th and 80th day of the treatment in order to evaluate the cat’s response to the treatment and change the dosage accordingly.

It is worth mentioning that an incorrect observation of the treatment or an incorrect dosage change might cause drug resistance or increase the probability of a relapse during the post-treatment observation period.

What happens after 84 days of drug treatment?

After the treatment period comes the observation period. During this time, complete blood count, ultrasound, and regular examination are also needed on the 30th, 60th and 80th day. It is still necessary to check the cat’s weight and if there are any signs that the cat might relapse. It is important to mention that relapses are unusual and they mostly occur due to incorrect observation or drug resistance.

Once the cat has successfully finished the 168-days period of treatment and observation, it is officially considered cured and can get discharged from the clinic.

We also have to consider for the treatment:

  1. GS is not a miracle worker. The drug treats and cures FIP but the cat may need another complementary therapy to improve its health, or other types of care during the treatment so that it succeeds.
  1. Symptom management: In the cases of the wet form of FIP, drainage may be done only to reduce the fluid concentration in the abdominal or chest cavities, or to gather a sample for analysis. This may provide some temporary relief and improve the cat’s quality of life. If the cat needs it, temporary use of corticoides is allowed . Do not use quinolone antibiotics (enrofloxacin and marbofloxacin). And never drain all the fluid.
  2. Nutritional support: It is key to guarantee that the infected cat gets proper nutrition. In some cases, they may require special diets or supplements to stay in good health or maintain their weight. Adding wet food to their diet during treatment is also very important.
  3. Stress control: Reducing stressful situations in the cat’s life may be positive for its improvement. Keeping a calm and predictable environment may help reduce stress and improve immune response. During the treatment, moving and going on vacations should be avoided. In case there is no choice but to go through a stressful situation, ask your veterinarian for preventivemeasures.

If your cat was diagnosed with FIP, the treatment may vary according to every cat’s particual situation. Always seek guidance and advice from a veterinarian with experience treating feline infectious peritonitis.

Prevention and Care:

Remember that FIP is not contagious. The virus that can be transmitted is the underlying coronavirus, which generally only causes diarrhea. This virus is responsive to common disinfectants like bleach and it can survive in the environment for up to 2 months. However, also remember that it is considered that most cats carry the coronavirus or have already been exposed to it. Therefore, you do not need to keep the FIP-infected cat away from the rest of your cats. In fact, doing so can be detrimental during the treatment because it causes stress.

Dr. Gabriela Despuys
Veterinary Doctor
M.N. 8924
Specialist in Domestic Feline Medicine (UNR)
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