How Is FIP Diagnosed? A Guide for Cat Parents

Feline Infectious Peritonitis (FIP) is one of the trickiest diseases to diagnose in cats. There's no single test that says, "Yes, this is FIP." Instead, vets have to connect the dots using a mix of symptoms, lab results, and sometimes even advanced imaging or tissue tests. 

You might feel overwhelmed hearing your vet mention terms like "Rivalta Test" or "PCR." Don’t worry, through this article, Basmi FIP Philippines will break things down in a simple and clear way.

Why Diagnosing FIP Is a Real Challenge

FIP symptoms can look like other common illnesses. Fever, fatigue, weight loss, and tummy swelling? It could be FIP, or it could be something else.

That’s why there’s no one-size-fits-all test. Instead, vets piece together the clues based on what they see and the results of several different tests.

There are two types of FIP: wet (effusive) and dry (non-effusive). Wet FIP often shows fluid buildup in the belly or chest, while dry FIP comes with more subtle signs like eye problems or neurological issues. 

That makes diagnosing dry FIP especially tough.

6 Ways to Diagnose FIP in Cats

You can find out if your cat has FIP through a series of tests, starting from observing clinical symptoms to biopsies.

Let’s check out the full explanation!

1. Initial Evaluation and Symptom Check

Your vet will start by checking your cat’s clinical signs and asking about their health history. Symptoms that make vets suspect FIP include:

• Persistent fever that doesn’t respond to antibiotics,

• Weight loss

• Loss of appetite

• Weakness

• Abdominal swelling (for wet FIP)
  

If these signs match up, your vet may suggest further testing.

2. Blood Work and A/G Ratio

A Complete Blood Count (CBC) and biochemistry panel are usually the first tests done. These give clues about what’s happening inside your cat’s body.

• Low albumin

• High globulin

• Low red blood cells (anemia)

• High white blood cells

• A low Albumin/Globulin (A/G) ratio below 0.5
  

These results don’t confirm FIP, but they can raise suspicion and help your vet decide what to do next.

3. Rivalta Test

If there’s fluid in your cat’s abdomen or chest, the Rivalta test might be done. It’s a simple test that tells whether the fluid is likely caused by FIP.

• A positive Rivalta result increases the chances that your cat has FIP.

• A negative result doesn’t completely rule it out, especially in dry cases.
  

Ask your local vet clinic in the Philippines if they offer this test—not all clinics do.

4. PCR and Antibody Testing in the Philippines

PCR (Polymerase Chain Reaction) testing looks for the FIP virus's genetic material in fluid or tissue samples. It can be very helpful, especially when it detects the mutated virus associated with FIP.

However, many cats carry feline coronavirus (FCoV) without getting sick. That means a positive PCR doesn’t always equal FIP.

Some clinics in the Philippines also offer antibody tests to see if your cat has been exposed to FCoV. These tests are useful but not 100% accurate when used alone.

5. Imaging with X-rays and Ultrasound

If there isn’t obvious fluid, vets might turn to imaging tools. X-rays and ultrasounds can help:

• Detect hidden fluid buildup

• Spot enlarged organs (like liver, spleen, or lymph nodes)

• Look for signs of inflammation
  

This is especially useful in dry FIP cases, where physical symptoms are more subtle.

6. Confirmatory Tests – IHC and Biopsy

For the most definitive diagnosis, vets may suggest a biopsy with Immunohistochemistry (IHC) testing. This involves taking a tissue sample and checking for the virus under a microscope.

In the Philippines, this procedure can be costly and may require sending samples to specialized labs. It could cost around $150 or approximately ₱8,313. It also takes time, and not every clinic offers it.

Because of this, most vets rely on strong clinical signs and treatment responses.

GS-441524: The Treatment Changing Lives

The good news? FIP is no longer a death sentence. 

Many cats have fully recovered thanks to GS-441524, an antiviral drug that stops the virus from replicating. The treatment usually lasts around 84 days, with doses adjusted based on the cat’s weight and symptoms.

You can now find licensed GS medication and expert guidance in the Philippines through support teams like Basmi FIP Philippines.

Final Thought

FIP may be complicated, but diagnosing it has come a long way. If your cat is showing signs, don’t wait. Ask your vet about these diagnostic options or reach out to the Basmi FIP PH Team via Viber for support.

With early action and the right care, recovery is possible. You and your cat don’t have to face this journey alone.