Is It Really FIP or Just Symptoms of Another Disease? Let’s Find Out!

Feline Infectious Peritonitis (FIP) is a disease caused by a mutation of the Feline Coronavirus (FCoV). Usually, when a pawrent hears that their cat has been diagnosed with FIP, sadness, fear, and worry instantly take over.

And who could blame them? FIP spreads fast and aggressively. If diagnosis is delayed and your cat doesn't receive treatment in time, their life could be at serious risk.

But here's the problem: diagnosing FIP in cats is far from easy. That’s because several other illnesses can show symptoms that resemble FIP. As a result, misdiagnosis is very likely.

So, what can you do to avoid a misdiagnosis? Let’s dive into the answer! The BasmiFIP Philippines team has put together everything you need to know in this article.

Why Is FIP Diagnosis Often So Confusing?

Diagnosing FIP can be confusing and challenging because the early symptoms can mimic a wide range of other conditions. We’re talking about symptoms like:

• Fever

• Vomiting

• Appetite loss

• Weight loss

On top of that, as many pawrents already know, FIP has four different types:

• Wet FIP

• Dry FIP

• Ocular FIP

• Neurological FIP

Each type presents different symptoms, which makes the diagnosis even more complicated.

Things get even more difficult when your cat already has other underlying illnesses (comorbidities). These can confuse vets even more during the diagnostic process.

That’s because they need to determine whether the symptoms are really caused by the FCoV mutation—or by a pre-existing condition that your cat already had.

Why Accurate Diagnosis Is Key to the Right Treatment

Just like in humans, correct diagnosis is the first and most critical step toward recovery. If a mistake is made in diagnosis, the disease might progress further—or even take your cat’s life.

For cats with FIP, accurate diagnosis and fast action are absolutely essential. The sooner and more precisely FIP is detected, the higher your cat’s chances of survival.

Currently, the most effective treatment known for FIP is GS-441524. At BasmiFIP Philippines, this antiviral is prescribed in carefully calculated doses, depending on your cat’s:

• FIP type

• Weight

• Blood test results

That’s why a correct diagnosis is crucial—so that GS-441524 can work effectively in your cat’s body.

Common Symptoms That Often Lead to Misdiagnosis

Here are the general symptoms of FIP that are also found in many other diseases—making misdiagnosis more likely:

• High fever

• Ongoing vomiting

• Digestive problems (diarrhea or constipation)

• Appetite loss

• Rapid weight loss

• Lethargy or weakness

• Swollen lymph nodes

Diseases That Are Often Mistaken for FIP

Toxoplasmosis

Caused by a parasite called Toxoplasma gondii, infected cats may show symptoms like fever, appetite loss, lethargy, and seizures. Seizures and weakness are also signs of neurological FIP, making things very tricky. That’s why additional testing is essential.

FeLV (Feline Leukemia Virus)

Just like FIP, this virus is spread through saliva, urine, and feces. It can even trigger the onset of FIP. Cats with FeLV may appear healthy for a long time before severe symptoms appear.

FIV (Feline Immunodeficiency Virus)

FIV weakens a cat’s immune system, making them more prone to infections. Since FIV affects multiple organs, it’s often mistaken for FIP, even though treatment is completely different.

FPV (Feline Panleukopenia Virus)

Cats with FPV usually have symptoms like fever, vomiting, diarrhea, and appetite loss—very similar to FIP. This is why extra testing and follow-up checks are needed.

IBD (Inflammatory Bowel Disease)

IBD causes vomiting, diarrhea, and weight loss due to intestinal inflammation. These symptoms can easily be confused with FIP—especially if the FIP case affects the digestive tract.

Lymphoma

This cancer targets the lymph nodes and internal organs. Like FIP, it causes internal inflammation, making diagnosis even harder—even for experienced vets.

Cancer

Yes—cats can get cancer, too. And just like FIP, it’s a serious disease that requires urgent treatment. The problem is, both diseases often show similar symptoms: fever, weight loss, weakness, and refusal to eat.

Tests to Help Distinguish FIP from Other Diseases

To confirm if your cat really has FIP, your vet will need to run several tests. Here's a quick look at the most common ones:

Blood Test (CBC & Chemistry Panel)

This is the most basic and widely used test. It helps your vet get a general overview of your cat’s health. They’ll look at:

• Albumin levels

• Globulin levels

• Red and white blood cells

• A/G ratio

From there, the vet can determine what further tests are needed.

Rivalta Test

This is used only for wet FIP. It helps verify whether the fluid buildup in your cat’s abdomen is caused by FIP. If your cat has no abdominal swelling, this test won’t be used.

X-Ray and Ultrasound (USG)

These are imaging tools that help assess your cat’s internal organs. They’re mainly used to detect fluid accumulation, enlarged organs, or inflammation in the chest and abdomen.

MRI

An MRI uses magnets and radio waves to create detailed images of soft tissues, including the brain, spinal cord, and blood vessels. It’s especially useful for suspected neurological FIP.

Biopsy

A biopsy involves taking a tissue sample from an organ or lymph node and sending it to the lab for analysis. But due to high cost and longer wait times, vets usually recommend other tests first.

When Should You Suspect It’s NOT FIP?

If all tests have been done and the results remain unclear, your cat can start treatment with GS-441524 as a trial.

To find the right dosage, chat with BasmiFIP Philippines via Viber for assistance.

If there’s no improvement within two weeks or your cat seems to reject the medication, contact your vet immediately for further evaluation.

The Vet’s Role and Importance of Ongoing Follow-Ups

Seeing your usually energetic and affectionate cat suddenly become quiet and weak can be heartbreaking. That’s why you need the guidance and support of a professional veterinarian.

With a proper diagnosis, you can be there for your cat throughout their healing journey. Yes, recovery may be long and tiring—but you don’t have to go through it alone.

BasmiFIP Philippines is always here for you. We’re happy to answer any of your questions—even if you just need to vent about your worries.

Once your vet has confirmed the diagnosis and you’ve started your cat on the correct GS-441524 dose recommended by BasmiFIP Philippines, don’t forget to do follow-up tests on days 30, 60, and 84.

These check-ups are vital to make sure your cat is truly getting better—or if another disease might be hiding behind the symptoms.

Conclusion

FIP shares symptoms with many other illnesses, so thorough testing is essential before confirming a diagnosis.

Trust your vet—and the BasmiFIP Philippines team—to give your cat the best possible care and support throughout the journey to recovery.