FIP is no longer a death sentence for cats. Here’s everything you need to know about it, including the latest treatment options.

Much like the flu in humans, FIP is caused by a viral infection. The culprit is feline coronavirus, a common virus that infects 40%–80% of cats worldwide. AnimalBiome’s Chief Science Officer, Dr. Holly Ganz, describes feline coronavirus as “highly prevalent” in young cats. Like the flu, it usually causes only mild symptoms (if any at all), which disappear as young cats mature and their immune systems develop. 

However, in rare cases, feline coronavirus results in the often-fatal disease FIP. Here, the mutated virus infects white blood cells, and triggers an intense immune system response. The resulting inflammation can wreak havoc in the intestines, brain, and gut.

FIP occurs in two forms: “dry” (non-effusive) and “wet” (effusive). The dry form of FIP may cause loss of appetite, weight loss, depression, and fever. The wet form of FIP causes fluid to accumulate in the abdomen or chest, which leads to a pot-bellied appearance and can interfere with a cat’s breathing. Both forms of FIP can cause neurological symptoms, like seizures or loss of coordination. 

Up to this point, the lack of an FIP cure left pet parents and veterinarians in a heartbreaking position, with no option other than euthanasia.

Infection typically occurs when a healthy cat comes into oral contact with feces from an infected cat. Only about one-third of infected cats shed the virus in their feces, and most only do so for a few months. However, a small percentage may shed the virus throughout their lives. 

Feline coronavirus can also remain dormant in the body for months or even years before mutating and causing FIP, even in healthy cats.

FIP is challenging to diagnose because its clinical signs overlap with other cat diseases. Blood tests may show abnormalities, but none are specific to FIP. X-rays can detect fluid in the abdomen, which can be analyzed for FIP, but it’s not always conclusive. FIP may also coexist with other conditions, further complicating the diagnosis. 

Currently, the only definitive ways to diagnose FIP are via a post-mortem exam, or through examination of an infected tissue sample. Your veterinarian may take a biopsy from your cat for this reason.

Feline infectious peritonitis used to be a death sentence for cats. Now for the first time, an antiviral drug has shown to be effective at treating FIP. Thousands of cats have been cured over the last three years.

One of those lucky cats is Jynx.

A happy, playful kitten, Jynx was adopted in November 2020 at 4.5 months old. But just a few months later, he suddenly became withdrawn and lethargic. Then he started hiding, wouldn’t eat, and his belly began to swell. 

So Jynx was rushed to the ER in the middle of the pandemic. “Within 30 minutes they called to tell us how sick he was; he had days to live,” recalled Jynx’s distraught adopter, Lynn. He had all the symptoms of FIP — and as many cat parents will know, there is no cure. 

However, Lynn’s veterinarian told her about an expensive black market drug with great success rates. 

“It would cost $8k+, but we didn’t think twice,” said Lynn, who raced off to find a source. The most common form of the drug was an injectable version. While she was prepared to do anything to save Jynx, Lynn also knew weeks of daily injections would be painful and stressful for her beloved cat, who was already suffering. 

Luckily, Lynn managed to source an oral version of the drug. She started Jynx on the medication right away. “Giving him pills was a challenge, as most cat parents know,” Lynn said. But Jynx responded quickly. 

“Within days he had more energy. After 10 days Jynx knew the pills were helping, and we didn’t need to use a piller or restrain him,” shared Lynn. “He would gobble the pills up and would even wake us up on time for his pills!” 

Within a few weeks, Jynx was back to his playful, goofy self.