Peritonitis is the term used to describe inflammation of the peritoneum, the membrane that lines the inner wall of the abdomen and covers most of the abdominal organs. Peritonitis can be very severe in rabbits and life threatening in many cases. For this reason it is essential to identify and treat the cause as soon as possible.

The most common cause of peritonitis is faecal contamination of the abdominal cavity due to perforation of the gastrointestinal tract, often due to severe obstruction. Other causes are rupture of other internal organs such as liver, bladder or uterus, abdominal injuries due to external trauma and predator bites, infectious diseases and wound breakdown following surgery.

Peritonitis can be acute or chronic; acute when it has a sudden onset, and chronic when it occurs over a period of time. Acute peritonitis is normally the result of infection due to bacteria, namely E. coli. This is a severe form of peritonitis and the vast majority of rabbits do not survive this form. If the rabbit does survive then they often develop chronic peritonitis in the coming days. Chronic peritonitis may result from an after effect of acute peritonitis, abscesses within the abdomen, or complications following abdominal surgery.

A rabbit with peritonitis is generally lethargic with reduced appetite and faecal output. Other clinical signs are severe pain and abdominal distension. Due to the pain, the rabbit is generally reluctant to move and often grinds the teeth. The respiratory rate is also likely to be high due to the amount of discomfort. In severe cases, the rabbit also has a fever and can even be in a state of collapse due to the shock.

However, all of these symptoms are non-specific and also analytic of many other problems, so it is important to take your rabbit to see your vet straight away and do not wait to see if they improve.

An initial diagnosis of peritonitis is based on clinical signs and physical examination. Your vet will then confirm diagnosis by performing an abdominocentesis. This technique involves inserting a needle into the rabbit’s abdomen to see if there is any evidence of ‘free fluid’ and, if possible, collect a sample. This is often performed in the conscious rabbit, but it may need to be sedated to reduce the stress caused by the pain. The sample collected can be tested for bacteria if an infection is suspected.

X-rays, ultrasound and blood tests are also likely to be performed in order to determine the cause of peritonitis and evaluate the severity of the condition.

An exploratory laparotomy, which involves giving the rabbit a general anaesthetic to surgically operate on and open the abdomen, may be performed by the vet to better evaluate the abdominal organs and determine the cause of peritonitis.

Intensive medical and supportive treatment is generally necessary. This consists of fluid therapy to treat the shock, broad spectrum antibiotics, strong painkillers, and assisted feeding. In severe cases, abdominal lavage under general anaesthesia is also performed. Abdominal lavage consists of profuse flushing of the abdominal cavity with warm sterile saline in order to remove the contaminating material and ‘clean’ the abdominal cavity as much as possible.

As part of treatment, it is also necessary to identify the cause of peritonitis and remove or treat it when possible. It is often a waiting game to see if the rabbit responds to treatment, which can take many days or weeks of intensive treatment.

The prognosis depends on the severity of the peritonitis, however it is generally considered poor.

In order to have a better prognosis, it is important that treatment is started as soon as the rabbit shows the first signs of illness. Due to the acute onset and fact that most rabbits are only presented once they are extremely ill, means that even with intensive veterinary care, the vast majority do not survive.