Feline Infectious Peritonitis Treatment with Interferon

Feline infectious peritonitis is a viral disease that can affect any domesticated cat. It is a deadly condition, and is very difficult to treat. In many cases, the cat’s immune system will actually work to make the infection worse. All cats can be infected, but very young kittens and old cats are most susceptible. The disease can spread between cats through their bodily fluids or feces. Interferon, a natural protein that stimulates the cat’s immune system, has been used as an effective replacement for traditional treatments.

Symptoms of Feline Infectious Peritonitis

Because feline infectious peritonitis (FIP) can affect any soft tissue system in a cat’s body, the disease can give rise to a wide variety of symptoms. There are two forms of FIP, the effusive form and the dry form, and cats with the effusive form can accumulate large quantities of fluid in the chest and abdominal cavities. The effusive form can be easily identified in cats, because the fluid buildup will give the animal a very pot-bellied appearance. Some of the most common symptoms of both the dry and effusive forms of feline infectious peritonitis are:

  • Fluctuating fever
  • Lethargy
  • Weight loss
  • Loss of appetite

If the cat’s central nervous system is infected with the disease, it could also display some neurological symptoms.


If a cat is affected by the effusive form of feline infectious peritonitis, the disease can be diagnosed using fluid cytology, or analysis of the fluids collecting in the cat’s body. The most effective method of diagnosing FIP in the dry form is a histopathological examination, which involves scraping small tissue samples and examining them under a microscope. There are also certain tests available that search blood samples for antibodies for the virus, and tests that search the blood for chemicals, called polymerase chains, that are only associated with the FIP virus.

Traditional Treatment

Traditional treatments of feline infectious peritonitis include a combination of immunosuppressant and antiviral drugs. The immunosuppressants were used because the cat’s immune system usually works against the cat in a FIP infection, and the antiviral drugs were used to help kill the virus itself. These treatments were generally ineffective, because the immunosuppressant drugs would suppress the cat’s natural defenses, while the antiviral drugs were usually toxic to the cat as well as the virus.

Treatment Using Interferon

Interferon helps the feline immune system fight off a peritonitis infection by helping to identify infected host cells. These cells can then be destroyed, along with the viruses they contain. While interferon treatment is still not very effective (it only works on about 30 percent of cats), it is one of the most effective treatments available. It is administered orally in daily dosages, and has led some cats to a complete recovery. The daily interferon dosage for cats with non-effusive feline infectious peritonitis is 30 IU (international unit). If a cat has effusive FIP, it is usually given an interferon dose of 30 IU or more intramuscularly.

Side Effects of Interferon

The most common side effect of interferon injections in cats consists of a range of flu-like symptoms. These can range from mild to severe. Other possible side effects are much more prevalent in cats that receive higher doses. They include:

  • Fatigue
  • Diarrhea
  • Joint pain
  • Dizziness
  • Nausea
  • Vomiting

Rare side effects include anorexia, increased heart rate, confusion, low white blood cell count and hormonal imbalances.

Interferon is a protein that can help to increase the chances of survival for cats infected with this disease. If your cat is suffering from feline infectious peritonitis, you should seek interferon treatment immediately.