Types of FIP in Cats: Wet vs. Dry FIP

Feline Infectious Peritonitis (FIP) is a devastating disease caused by a mutation of the feline coronavirus (FCoV). While once considered fatal, recent advancements in treatment, especially the use of GS-441524, have brought new hope to pet owners.

To better understand how FIP presents and progresses, it’s important to explore its two main forms: Wet (Effusive) FIP and Dry (Non-Effusive) FIP. This article breaks down the differences between these types, their symptoms, diagnosis, and how they respond to treatment.

🧬 Overview of FIP Classification

FIP is broadly classified into two types:

• Wet FIP (Effusive): Characterized by the buildup of fluid in body cavities (abdomen or chest).

• Dry FIP (Non-Effusive): Characterized by granulomas (inflammatory lesions) affecting internal organs without fluid accumulation.

While some cats fall into one category, others may show mixed features, transitioning between types or showing symptoms of both.

💧 What Is Wet FIP? (Effusive Type)

Wet FIP is the more common and faster-progressing form of the disease. It results from severe inflammation of the blood vessels (vasculitis), which causes leakage of protein-rich fluid into body cavities.

🔍 Key Features

• Rapid onset and progression

• Fluid accumulation in the abdomen (ascites) or chest (pleural effusion)

• Abdominal swelling or difficulty breathing

🐱 Symptoms of Wet FIP

• Distended belly due to fluid buildup

• Labored or rapid breathing

• A fever that doesn’t respond to antibiotics

• Lethargy and weight loss

• Loss of appetite

Wet FIP is easier to diagnose because the fluid can be extracted and tested (e.g., Rivalta test, PCR, cytology).

🧱 What Is Dry FIP? (Non-Effusive Type)

Dry FIP does not involve fluid buildup. Instead, it causes granulomatous lesions in organs like the liver, kidneys, lymph nodes, eyes, and brain. This form has a slower progression but can be harder to diagnose.

🔍 Key Features

• No fluid accumulation

• Localized inflammation affecting internal organs or the nervous system

• Often mistaken for other chronic conditions

🐱 Symptoms of Dry FIP

• Neurological issues: tremors, seizures, unsteady gait

• Ocular symptoms: uveitis, cloudy eyes, vision loss

• Jaundice (yellowing of the eyes or gums)

• Enlarged lymph nodes or organs

• Persistent fever, weight loss, and fatigue

Dry FIP may affect one or more systems: the central nervous system (CNS), eyes, or organs. Neurological FIP is a subset of dry FIP and is especially difficult to diagnose and treat.

⚖️ Key Differences Between Wet and Dry FIP

Feature	Wet FIP (Effusive)	Dry FIP (Non-Effusive)
Fluid Buildup	Yes – in the abdomen or chest	No
Onset	Rapid	Gradual
Common Symptoms	Abdominal swelling, breathing issues	Neurological, ocular, or organ-specific signs
Diagnosis	Easier – fluid can be tested	Harder – requires bloodwork, imaging, biopsy
Prevalence	More common	Less common, but not rare

🧪 How Each Type Is Diagnosed?

Diagnosis of FIP remains complex due to the lack of a single definitive test. However, the approach differs slightly between wet and dry forms:

🧫 Wet FIP

• Analysis of effusion fluid (Rivalta test, protein levels, cell types)

• Fluid PCR for FCoV RNA

• Imaging (ultrasound, X-ray)
  

🧬 Dry FIP

• Blood tests: high globulin levels, low albumin/globulin ratio

• Imaging to detect organ enlargement or lesions

• Cerebrospinal fluid analysis (in neuro cases)

• Ocular examination for inflammation

• Biopsy or fine needle aspirates (for granulomas)

Confirming FIP often involves ruling out other diseases, including FeLV, FIV, lymphoma, and bacterial infections.

💊 Treatment Response in Wet vs. Dry FIP

The good news is that both forms of FIP respond to antiviral treatment, especially GS-441524. However, response and treatment duration may vary.

🟦 Wet FIP

• Often responds more quickly to GS-441524

• Visible improvement in appetite and activity within days to weeks

• Shorter treatment course (~12 weeks), depending on severity
  

🟨 Dry FIP

• Slower to respond, especially in neurological or ocular forms

• May require higher doses of GS-441524 and longer treatment duration

• Neurological cases may need 15+ weeks of therapy and close monitoring

Prognosis for both types is greatly improved with early and consistent treatment. CureFIP USA provides both injectable and oral FIP treatment options with full guidance and dosing support.

✅ Early Detection & Proper Treatment Save Lives

FIP, whether wet or dry, was once considered a death sentence. Today, thanks to antiviral treatments like GS-441524, thousands of cats have survived and thrived after a diagnosis.

Recognizing the differences between wet and dry FIP allows for faster diagnosis and treatment. Pet owners should act quickly if they observe any suspicious symptoms, especially in young cats or multi-cat households.

For accurate diagnosis and high-quality treatment, reach out to CureFIP USA for expert guidance, trusted medications, and full recovery support.