Peritonitis is inflammation of the peritoneum, the membrane that lines the abdominal cavity. It is a serious and often fatal condition. Peritonitis may be short- or longterm, localized or widespread. Most commonly it occurs due to contamination of the peritoneal cavity (for example by perforation of the abdominal cavity by a foreign object, the splitting open of an abdominal wound closure, or rupture of the intestine due to the presence of a swallowed foreign object), but it also may be caused by infectious agents such as viruses or bacteria.

Fever, blood poisoning, shock, reduced blood pressure, hemorrhage, abdominal pain, paralytic obstruction of the intestines with reduced fecal output, and fluid accumulation within the abdominal cavity may all be signs of peritonitis. Rupture of the gastrointestinal tract, with spillage of large volumes of intestinal contents, leads to short-term peritonitis. Death due to shock from the large amounts of bacterial toxins may occur suddenly.

The first priority of treatment is to stabilize the consequences of peritonitis, such as changes in electrolytes, acid-base imbalance, fluid loss, and blood clotting abnormalities. In addition, your veterinarian will want to identify the point of origin of inflammation and correct or remove it. Antibiotics are a standard part of the treatment. Replacement fluids, electrolytes, plasma, or whole blood may be necessary to maintain heart output.

Once the cat is stabilized, surgery is done to explore the abdomen and to repair any defects. Your veterinarian will follow this with a thorough rinsing of the abdominal cavity with a saline solution, antiseptics, or antibiotics. Antibiotics are continued after surgery. Nutritional support with intravenous feeding may be needed, as many cats with peritonitis will not eat after surgery. In cats with blood poisoning and shock, fluids, electrolytes, and antibiotics are crucial elements of treatment.

Last full review/revision July 2011 by Otto M. Radostits, CM, DVM, MSc, DACVIM (Deceased); Eugene D. Janzen, DVM, MVS; Jodie Low Choy, BVMS; Dennis W. Macy, MS, DACVIM; Dudley L. McCaw, DVM, DACVIM (Small Animal, Oncology); Barton W. Rohrbach, VMD, MPH, DACVPM; J. Glenn Songer, PhD; Richard A. Squires, BVSc (Hons), PhD, DVR, DACVIM, DECVIM-CA, MRCVS; Bert E. Stromberg, PhD; Joseph Taboada, DVM, DACVIM; Charles O. Thoen, DVM, PhD; John F. Timoney, MVB, PhD, Dsc, MRCVS; Ian Tizard, BVMS, PhD, DACVM; Max J. Appel, DMV, PhD; David A. Ashford, DVM, MPH, DS; Stephen C. Barr, BVSc, MVS, PhD, DACVIM; J. P. Dubey, MVSc, PhD; Paul Ettestad, DVM, MS; Craig E. Greene, DVM, MS; Delores E. Hill, PhD; Johnny D. Hoskins, DVM, PhD