fiP

Feline infectious peritonitis (FIP) is a fatal inflammatory disease of cats caused by certain mutations of feline coronavirus (FCoV). Although many cats harbor FCoV, only a minority develop FIP, typically when the virus mutates within the host and provokes an abnormal immune response. The virus is common in multi-cat environments and is usually transmitted via the fecal-oral route.

FIP presents in two major forms: wet (effusive) and dry (non-effusive). In the wet form, immune-mediated inflammation leads to leakage of fluid into body cavities, most often the abdomen or chest, causing distension and respiratory compromise. In the dry form, granulomatous lesions develop in organs such as the liver, kidneys, lymph nodes, eyes, and nervous system, leading to organ dysfunction without significant effusion.

Clinical signs are often nonspecific and include persistent fever, weight loss, lethargy, and poor appetite. Wet FIP may cause abdominal swelling or fluid accumulation in the chest, while dry FIP can cause ocular changes, neurological symptoms, or organ-specific signs depending on lesion location. Diagnosis relies on a combination of clinical signs, laboratory tests showing hyperglobulinemia or an altered albumin-to-globulin ratio, Rivalta testing, detection of FCoV RNA in effusions, imaging, and sometimes tissue biopsy.

There is no universally proven cure for FIP. Historically, prognosis has been poor, with supportive care offering limited benefit. Recently, antiviral therapies have shown promise in some cases, and there is ongoing research and compassionate use in certain regions. A vaccine exists in some countries but is not universally recommended due to variable efficacy.

Prevention focuses on reducing FCoV exposure and transmission, especially in multi-cat environments, through good hygiene, litter box management, reducing stress, and limiting overcrowding.