Cat FIP Wet Form Diagnosis and Fluid Management

Wet (effusive) FIP presents with fluid accumulation in body cavities and requires urgent diagnosis and antiviral treatment to prevent rapid deterioration.

Key Facts

Wet FIP accounts for approximately 60-70% of FIP cases and progresses more rapidly than dry FIP
Fluid accumulates in the abdomen, chest, or around the heart due to severe vascular inflammation
The effusion fluid has characteristic protein-rich, straw-colored appearance with high albumin:globulin ratio
PCR testing on effusion fluid is highly sensitive for FIP diagnosis
Antiviral therapy with GS-441524 or remdesivir-based drugs typically causes dramatic improvement within 1-2 weeks
Effusion volume can be reduced by thoracocentesis or abdominocentesis to improve comfort during early treatment
Relapses after completing treatment may present as conversion to dry form

Welfare Considerations

Wet FIP causes significant discomfort from fluid accumulation - abdominal distension impairs normal movement and chest fluid causes dyspnea. Cats deteriorate rapidly without treatment. The dramatic improvement seen within days of starting antivirals is profoundly welfare-positive. Drainage of large effusions provides immediate comfort while antivirals take effect.

What You Can Do

Seek evaluation urgently for any young cat with abdominal distension, respiratory difficulty, or high fever
Request FIP-focused testing including effusion fluid analysis and PCR when FIP is suspected
Find a vet experienced with FIP antiviral protocols - not all practitioners are familiar with current treatment
Join FIP support communities for guidance on treatment sourcing and monitoring
Monitor weight, appetite, and breathing closely during early treatment weeks