Peritonitis is an inflammatory process within the abdomen that involves the peritoneum and can be localized or generalized. Localized peritonitis can occur following surgery, trauma or mild pancreatitis and usually responds to medical therapy.

Generalized peritonitis is very serious and potentially life threatening and is due to inflammation that overwhelms the body's normal responses. Fluid accumulates within the abdomen and eventually, dehydration, weakness and metabolic abnormalities occur. Some animals may progress to septic shock. The dehydration often results from a lack of available body fluid. These losses occur associated with vomiting, diarrhea, pooling of abdominal fluid and fever. Generalized peritonitis can occur following gastrointestinal surgery, penetrating injury and severe pancreatitis. Generalized peritonitis requires aggressive medical and often surgical therapy.

Causes

There are a variety of causes of peritonitis. Peritonitis can be primary or secondary. Primary peritonitis is uncommon and is caused by a direct infection of the peritoneum. Feline infectious peritonitis is the only significant cause of primary peritonitis in cats. Secondary peritonitis is more common in companion animals. Secondary peritonitis is caused by contamination of the abdomen. Some causes include ruptured urinary bladder, ruptured bile ducts or gallbladder, ruptured tumors or pancreatitis (inflammation of the pancreas) leading to leakage of pancreatic enzymes. Other causes include penetrating abdominal injury, perforated gastrointestinal ulcers, gastrointestinal foreign bodies, ruptured infected uterus, ruptured liver or prostatic abscess, severe pancreatitis and breakdown of a recent intestinal surgery site.

The most common cause of peritonitis is a loss of integrity of the bowel. This can occur due to perforation or dehiscence and is a main cause of peritonitis.