Diagnosis of FIP in cats

FIP may be considered more likely based on the following clinical features and examination findings:

• the cat is showing clinical signs compatible with FIP;
• the cat is in a higher-risk category (younger cats, colony or shelter cats, cats after stress, injury or severe illness, etc.);
• typical changes are seen on routine blood tests.

Typical changes on blood tests

• lymphopenia (low numbers of lymphocytes, a type of white blood cell);
• neutrophilia (increased numbers of neutrophils);
• anaemia (low red blood cells);
• elevated globulin concentrations (one of the major groups of proteins in the blood);
• an albumin to globulin ratio of < 0.8 raises the suspicion of FIP in a young cat. If the ratio is < 0.4 there is a > 90% likelihood that the diagnosis is FIP;
• elevated liver enzymes (e.g. ALT, ALP);
• elevated bilirubin (and jaundice, or yellowing of the gums and eyes).

Recommended further investigations

• further analysis of proteins in the blood — e.g. measuring alpha-1-acid glycoprotein (AGP);
• ultrasound examination of internal organs;
• MRI scans of the brain in case of neurological signs.