FIP in cats: causes, early signs and diagnosis

FCoV exposure is not the same as FIP

Feline coronavirus (FCoV) is common, particularly in multi-cat environments. Most exposed cats do not develop FIP. The disease arises when viral and individual immune factors produce systemic inflammation, so a positive coronavirus result alone does not diagnose FIP.

Signs worth recording

Early signs are often non-specific and overlap with other illnesses. Record when each change started and share the pattern with a veterinarian.

• Persistent or recurring fever, lethargy and reduced appetite
• Weight loss or poor growth
• A swollen abdomen, rapid breathing or breathing effort
• Eye inflammation, cloudiness or a change in vision
• Ataxia, tremors, seizures or altered behaviour

Why there is no single universal FIP test

AAFP/EveryCat guidance describes diagnosis as assembling compatible history, examination, laboratory results, imaging and appropriate samples. CBC, biochemistry, albumin-to-globulin ratio and inflammatory markers can change suspicion but do not confirm FIP alone.

When effusion is present, evaluating the fluid may be more informative than faecal testing. Test selection and interpretation depend on the clinical presentation and sample type.

PCR, antibody and Rivalta results need context

Faecal PCR can identify FCoV shedding but cannot prove FIP. Antibody tests indicate exposure. A Rivalta test can support assessment of an effusion, but a positive result is not specific to FIP and a negative result should not be interpreted in isolation.

Seek urgent veterinary care

• Breathing difficulty
• Seizures or sudden neurological deterioration
• Collapse or inability to eat or drink
• Rapid weakness or marked jaundice