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Best Cat Feline infectious peritonitis (FIP) Oral Treatment

Updated: Mar 19

Best Cat Feline infectious peritonitis (FIP)  Oral Treatment
Best Cat Feline infectious peritonitis (FIP) Oral Treatment

What is Feline Infectious Peritonitis (FIP)?

Feline infectious peritonitis (FIP) is a viral disease caused by feline coronavirus. It is a rare but fatal disease if left untreated.

What Cause of FIP Infection

Feline infectious peritonitis occurs when feline coronavirus undergoes a mutation during replication. By scientific estimates, this mutation occurs in 2~5% of cats that have contracted the feline coronavirus. It is important to note that while a majority of cats will contract feline coronavirus at some point in their lives, very few cats ever contract FIP.

The 2 Forms of FIP Infection

Clinically feline infectious peritonitis infections occur in two forms, effusive FIP also commonly called wet FIP and non-effusive FIP or dry FIP. The most easily identifiable clinical sign of wet FIP is the enlargement of the abdomen. This enlargement is caused by fluid accumulation inside the cat's bodies from internal organ inflammations as a result of feline infectious peritonitis virus (FIPV) infection and cat's body's natural reaction to it.

Non-effusive (dry) FIP are difficult to identify by the naked eye due to the lack of externally observable clinical symptoms that can definitively be linked to FIP. A series of tests must be conducted to deduce a dry FIP infection.

Veterinarians use several tests to reach a conclusive FIP diagnosis. The tests may include:

  • FCOV/FIP quick test

  • Complete blood examination

  • Tissue samples examination

  • Rivalta test

Common FIP symptoms include:

  • Persistent fever

  • Lack of desire for food

  • Lethargy

  • Difficulty breathing

  • Poor body coordination

  • Fluid in the abdomen

  • Fluid in the chest

  • Fluid in the lungs

  • Paralysis

  • Ocular symptoms

Your cat may experience several of the symptoms during a FIP infection. Do not take these symptoms lightly. They may indicate a serious health problem. Cats often fall victim to this veterinary disease because owners are not aware of the seriousness of these symptoms and doctors misdiagnose these symptoms, attributing them to more common but less fatal infections.

2 Treatment Options for Feline Infectious Peritonitis

The only clinically effective treatment for feline infection is a drug called GS-441524. It is a nucleoside analog closely related to the human antiviral drug Remdesivir that is used to treat Covid-19 patients, and is patented by Gilead Sciences. While Gilead Sciences decided not to pursue the commercialisation of GS-441524 for animal use, black market suppliers have appeared in China to fill the market demand from desperate cat owners around the world. There are currently two treatment options for FIP, subcutaneous injections and oral capsules/pills. Both options use GS-441524 as the active pharmaceutical ingredient (API).

Subcutaneous injections are the more consistent and therefore more reliable form of FIP treatment. Injections are recommended during the first 30 days of treatment or until the cat's FIP symptoms have subsided and condition has stabilised. The Injections are recommended if your cat is not eating or drinking, showing neurological symptoms of paralysis, cloudy eyes, poor movement coordination or difficulty breathing, has an infected or weak digestive system, or has a general weak immunity disposition. Injection form of GS-441524 is equally effective in treating wet or dry FIP.

The treatment option, while less consistent than injections, is generally preferred by cat owners. Some cats experience strong injection pain. Others develop an aversion to injections after days or weeks of GS treatment. Some cats struggle furiously at the sight of syringes or veterinary professionals who perform daily injections. Injection site sores may develop in some cats due to the highly acidic nature of injectable GS-441524. In these cases, oral GS-441524 in the forms of capsules or pills are acceptable alternatives to injections. Initial concerns of possible drug resistance to oral administration by researchers from UC Davis was proven unfounded. Oral form of GS-441524 is equally effective in treating wet or dry FIP.

Capsules vs Pills

While the effectiveness of oral capsules and pills are comparable to have Best FIP Cat Oral Treatment , capsules are easier to administer than pills. Capsules can be easily administered by either coating it with wet cat snacks, in which case cats would eat the capsules whole or by inserting capsules directly into the cat's mouth. Due to its smooth texture and absence of taste, cats readily swallow capsules without struggle. Capsules are more costly and cumbersome to produce, thus it is less preferred by manufacturers when compared to pills. is currently the only brand that offer capsule form of GS-441524.

Pills in contrast are faster and cheaper to manufacture. They are the first oral FIP treatment product to appear on the market. There are multiple brands that offer pills for treating FIP. Mutian and Aura/Spark, Capella, Lucky, Brava, and Kitty Care are current brands that offer oral pills for the treatment of feline infectious peritonitis. FIP oral pills are uncoated. They are small in size and can be administered without much struggle in a majority of cases. However, in a small number of cases, due to their taste and texture, some cats produce a gaging response and may spit out the pills if it has not travelled far enough down the esophagus, forcing the caregiver to repeat the process. Worse yet, some cats may vomit out the pills shortly after ingestion, thus an unpleasant experience and financial waste for cat owners.

When to switch from injections to oral fip treatment?

We recommend starting every FIP treatment with injections. It is the most effective and reliable method of treating FIPV. You should continue the injection for as long as possible, or until such times that

  • your cat can no longer tolerate daily injections.

  • you cat's eating and drinking habits have returned to normal.

  • Your cat no longer exhibit sever FIP symptoms such as neurological and ocular symptoms.

  • Your cat does not experience digestive complications often associated with FIP infections.

  • You can't do not vomit or diarrhoea frequently.

Introduce oral once when all of the above conditions are met. should the condition of your cat noticeably regress, depending on the severity, you may either increase oral treatment dosage and return to injections for the remaining days.

Cost Comparison between Injection and oral GS-441524

While GS is still a black market product, the prices of both injection and oral pills have reduced greatly since their introductions. Today the cost of GS treatment using injection form or oral form are comparable to each other.

How Effective are Oral FIP Treatments?

Oral FIP treatment, when administered at the appropriate time and dosage can be as effective against feline infectious peritonitis as subcutaneous injections. However, it is generally acknowledged by FIP treatment experts that cats are subject to a higher risk of relapse when given oral treatment when compared to injections for the duration of FIP treatment. Oral capsules and pills haven proven not as effective in treating cats suffering from neurological forms of FIP, or for cats that experience frequent vomiting or diarrhoea.

There are currently no known side effects from either injection or oral FIP treatment.


Thanks to the scientific discover by research teams in the USA and manufacturers in China, FIP treatment choices are becoming evermore diverse and accessible. While injections are still considered the more reliable method of treating FIP, oral capsules/pills, when used wisely and under the correct conditions, can be equally effective treating FIPV. Treatment success often depending on the experience and expertise of your vet. If your vet is not experienced treating feline infectious peritonitis, you may contact us for advice and guidance. Our email is

Best FIP Cat Oral Treatment

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