Acute Peritonitis

Peritonitis is an inflammation of the peritoneum, the membrane lining the walls of the abdominal and pelvic cavities and covering contained internal organs. In small animals, acute septic peritonitis is a relatively common and important condition with high mortality rates.1 Fluids, organic debris, cells, infectious organisms, and pus accumulate in the cavity in acute peritonitis. The causes can be from external injury or internal infections or diseases, such as bowel puncture from trauma, rupture from disease or ingested foreign bodies, with escape of contaminated bowel contents into the abdominal cavity; infections from abdominal cavity puncture, or after surgery, or spreading from infections in other abdominal organs or other areas of the body; damage to the urinary system, with escape of urine into the abdominal cavity; damage to the pancreas or liver with escape of bile or pancreatic enzymes into the abdominal cavity; and rupture of an infected uterus or prostate gland.

Dog with acute peritonitis

Acute peritonitis is accompanied by a severe pain. The dog usually walks with a stiff gait and the abdominal muscles are rigid in an attempt to guard the abdomen. There is loss of appetite, vomiting, fever, increased heart and respiratory rate, and feces may not be passed. Dehydration, hypovolemia, and sepsis may result in decreased body temperature and death.2 Signs of shock may develop within a few hours. The prognosis depends on the severity of the peritonitis and on how quickly treatment is started. Without treatment, acute peritonitis can be fatal.

The diagnosis is made based on the signs, physical examination, and evidence of fluid in the abdomen. X-rays and laboratory tests confirm the diagnosis. An abdominal fluid sample may be withdrawn and examined microscopically to assist in identifying the cause of the peritonitis. If bacterial infection is present, a culture and sensitivity test on the abdominal fluid to determine the antibiotic may be needed. Treatment is directed at removing the cause, and if organ rupture or perforation has occurred, surgery is essential to repair the injury or to drain an abscess. Treatment for shock, symptomatic and supportive care, including the use of pain relievers and intravenous feeding, will be required in most cases.


  1. Douglas H. Slatter (editor). Textbook of Small Animal Surgery
  2. Merck Manuals. Peritonitis

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