Types of FIP: Wet vs. Dry FIP

Feline Infectious Peritonitis (FIP) is a deadly disease in cats caused by a mutation of feline coronavirus (FCoV). Once rare and untreatable, FIP is now more widely recognized and, with modern antiviral therapies, can often be cured.

FIP appears in two main forms: Wet (Effusive) FIP and Dry (Non-Effusive) FIP. Each presents different symptoms and diagnostic challenges, and understanding these differences is critical for early detection and successful treatment, especially in regions like the GCC, where multi-cat households and indoor environments are common.

📊 Overview of FIP Types

There are two primary classifications of FIP:

Type of FIP	Description	Key Symptoms
Wet (Effusive)	Characterized by fluid accumulation in the abdomen or chest	Distended abdomen, labored breathing
Dry (Non-Effusive)	Characterized by inflammation in specific organs	Ocular or neurological symptoms, weight loss

Some cats may present with mixed symptoms, and in rare cases, the disease can evolve from one form to another.

💧 Wet (Effusive) FIP: Symptoms and Fluid Accumulation

Wet FIP accounts for approximately 60–70% of FIP cases. It is more acute and progresses faster than dry FIP.

🩺 Characteristics of Wet FIP:

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

• Yellowish or straw-colored fluid with high protein content

• Rapid progression of symptoms
  

🔍 Common Symptoms:

• Swollen or bloated abdomen

• Difficulty breathing or open-mouth breathing

• Lethargy and weakness

• Decreased appetite and weight loss

• A fever that does not respond to antibiotics

In wet FIP, the immune system's reaction to the mutated virus causes leaky blood vessels, leading to fluid buildup in body cavities. This is why early identification and drainage of fluid can be useful in diagnosis.

🔥 Dry (Non-Effusive) FIP: Organ-Specific Inflammation

Dry FIP is more chronic and subtle in its presentation, often affecting specific organs.

🩺 Characteristics of Dry FIP:

• Little or no fluid accumulation

• Granulomatous lesions in organs such as the kidneys, liver, brain, and eyes

• More difficult to diagnose due to varied symptoms
  

🔍 Common Symptoms:

• Neurological signs: seizures, wobbliness (ataxia), head tilt

• Ocular signs: inflammation, blindness, irregular pupils

• Jaundice

• Poor growth in kittens

• A fever that doesn’t respond to antibiotics

Because dry FIP can affect the central nervous system or the eyes, symptoms may appear slowly, and affected cats may be misdiagnosed with other chronic conditions.

🔄 Key Differences Between Wet and Dry FIP

Feature	Wet FIP	Dry FIP
Fluid Buildup	Yes (abdominal or chest)	No or minimal
Disease Progression	Rapid	Slower, chronic
Diagnosis	Easier via fluid analysis	More difficult, requires imaging or biopsy
Common Symptoms	Swollen belly, breathing issues	Ocular or neurological signs
Treatment Response	Typically faster to respond	May require a longer antiviral course

The same virus causes both forms, but the way the immune system reacts determines the type and severity of the disease.

🔁 Can Wet Turn into Dry FIP?

Yes, FIP types are not fixed. In some cases:

• A cat may initially present with wet FIP and later develop dry-type symptoms.

• Some cats may have mixed or overlapping signs (e.g., fluid buildup and neurological involvement).

This shift is thought to occur when the cat’s immune system begins limiting fluid leakage but fails to eliminate the virus from other tissues, leading to organ-specific inflammation.

Monitoring symptoms and working with a vet experienced in FIP is key for adjusting treatment as the disease evolves.

🧪 Diagnosis and Treatment Considerations

🔍 How Wet FIP is Diagnosed:

• Abdominocentesis or thoracocentesis: Extracting and testing fluid

• Fluid is typically yellow, sticky, and protein-rich

• Blood tests: Low albumin:globulin ratio, high white blood cells

• Imaging (ultrasound or X-rays) confirms fluid presence
  

🔍 How Dry FIP is Diagnosed:

• More complex, requires imaging (CT, MRI, ultrasound) or tissue biopsy

• Eye exams or neurological evaluations

• Blood work and acute phase proteins (like alpha-1-acid glycoprotein)
  

💊 Treatment for Both Types:

• GS-441524 antiviral injections or oral pills remain the gold standard

• Treatment duration: 84 days (12 weeks), though dry FIP may require longer

• Response time: Wet FIP cats often show improvement within days; dry FIP cases may take weeks

At CureFIP GCC, we offer both oral and injectable GS treatments, with guidance tailored to your cat’s specific symptoms and disease type.

🛡️ Final Thoughts: Early Action is Critical

Understanding the difference between wet and dry FIP can help save your cat’s life. While wet FIP is easier to diagnose and treat quickly, dry FIP requires vigilance and expert diagnosis. In both cases, early intervention with antiviral therapy offers the best chance of survival.

If you suspect your cat has FIP, contact a FIP-experienced veterinarian or reach out to CureFIP GCC for guidance on treatment protocols, dosage plans, and ongoing care.