Peritonitis in Cats

Katie Grzyb, DVM
By Katie Grzyb, DVM on Mar. 28, 2023

In This Article


What Is Peritonitis in Cats?

Peritonitis is inflammation (swelling) in the peritoneal, or abdominal, cavity. It contains all the abdominal organs, including the stomach, liver, gallbladder, spleen, pancreas, small and large intestines, kidneys, and adrenal glands.

The abdominal cavity and organs are lined with a thin membrane called the peritoneum. This membrane supports abdominal organs and acts as a passageway for nerves, blood vessels, and lymphatic vessels and nodes.

When the peritoneal cavity is injured, this membrane becomes inflamed. The inflammation can range from slight to severe, depending on the underlying cause. This condition is usually quite painful, but a veterinarian can investigate the cause and provide proper treatment.

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Symptoms of Peritonitis in Cats

Common symptoms of peritonitis in cats include:

  • Abdominal pain: You may notice your cat vocalizing when you pick them up, or they may have a bloated, firm abdomen and not move around much due to discomfort.

  • Increased heart rate or breathing rate, often associated with discomfort

  • Vomiting

  • Diarrhea

  • Restlessness or not being able to get into a comfortable position. Your cat may also get into a stretching position where their head is lowered and rear end is up; this helps relieve pressure from the abdominal organs.

  • Fever

  • Lethargy/weakness/collapse

  • Decreased appetite

  • Jaundice: Yellow discoloration of the skin, eyes, and ears can be a sign of specific types of peritonitis associated with liver/gallbladder disease or certain viruses, such as feline infectious peritonitis (FIP).

Causes of Peritonitis in Cats

Any foreign material or infections released into the peritoneal cavity cause irritation and start a systemic inflammatory response. This causes white blood cells to move into the peritoneal cavity, as well as more leaking of the blood vessels and lymphatics in the region.

The loss of fluid, white blood cells, and proteins into the abdomen decreases the movement of oxygenated blood through body tissues and organs. This eventually leads to cell death and organ failure if untreated or, unfortunately, sometimes even with treatment.

Causes of peritonitis in cats include:

  • Spread of infection through the bloodstream: bacterial, fungal, or viral (for example, FIP)

  • Opening of surgery sites in the gastrointestinal tract: This leads to leakage of material from the digestive tract and bacteria into the abdominal cavity.

  • Wounds that penetrate the abdomen

  • Liver abscesses (walled-off infections)

  • Blunt-force trauma to the abdomen: This leads to rupture of viscous (or balloon-like) organs such as the gallbladder, common bile duct, or urinary bladder. This fluid leakage encourages inflammation and bacterial contamination.

  • Severe pancreatitis

  • Pyometra (infected uterus in female cats that are not spayed)

  • Cysts or abscesses in the prostate (in male cats): This is rare.

How Veterinarians Diagnose Peritonitis in Cats

Your veterinarian will take a thorough history and do a complete physical examination to look for the underlying cause of peritonitis. Full blood work—including a complete blood count, biochemistry panel, electrolyte panel, and urinalysis—is often the first step.

Chest and abdominal X-rays are often the next steps to assess for fluid/gas in the abdomen and any obvious masses or foreign objects. Abdominal ultrasound is used to check all the abdominal organs for disease, leakage, or tumors.

If the vet finds fluid, they will usually take a sample with a needle, often with ultrasound guidance. This fluid is examined and sent to a laboratory for evaluation of blood, protein, bacteria, fungus, white blood cells, and cancerous cells.

If no fluid is noted, a peritoneal lavage may be considered. Sterile fluid is put into the abdomen to wash the lining of the peritoneal cavity. It is then removed from the abdomen to test for cells.

Treatment of Peritonitis in Cats

Cats with peritonitis should be hospitalized for the right fluid therapy and pain relief, as this is a painful disease. Specific therapy depends on the underlying cause:

  • Spread of infection through the bloodstream: Treatment includes surgery in some instances, as well as antibiotic, antifungal, or antiviral therapy.

  • Opening of surgery sites in the gastrointestinal tract: The vet will conduct surgical exploration to find the source of infection and repair the sites. Fluid therapy, pain relief, and antibiotic therapy is given at the vet clinic.

  • Wounds that penetrate the abdomen: Surgical exploration is done to find the source of trauma, and repairs are made as needed. Fluid therapy, pain relief, and antibiotic therapy is given at the vet clinic.

  • Liver abscesses (walled-off infections): Treatment will include surgical exploration and/or drainage of the abscess as well as antibiotic and fluid therapy.

  • Blunt-force trauma to the abdomen: The vet will do surgery to find the source of the leakage and make repairs. They will then give fluid therapy, pain relief, and antibiotic therapy.

  • Severe pancreatitis: This is treated at the vet hospital with intravenous (IV) fluid therapy, pain medication, anti-emetics, and antacid therapy.

  • Pyometra (infected uterus): The recommended treatment is surgical removal of the uterus to take out the source of infection, followed by fluid and antibiotic therapy.

  • Cysts or abscesses in the prostate: Treatment will be surgical exploration and/or drainage of the abscess as well as antibiotic and fluid therapy.

Recovery and Management of Peritonitis in Cats

It can take days to months for a cat to recover from peritonitis, and unfortunately, peritonitis can worsen even with the right diagnosis and therapy. Peritonitis can be fatal, and it usually is if left untreated.

If surgery is required to treat your cat, post-operative care is needed to heal from the surgery itself and will be at least two weeks long. Healing time is necessary for any underlying trauma also. It is important to give your cat pain and antibiotic medications at the times your veterinary team tells you to avoid unnecessary pain or resistance to therapies.

Ensuring that your cat is eating well is important, and you will probably need to feed them a bland diet for a few days to a few weeks as their abdomen heals. These diets may be recommended as lifelong treatment in certain cases of peritonitis.

Peritonitis in Cats FAQs

Is peritonitis the same as FIP (feline infectious peritonitis)?

FIP is a viral disease and is a type of peritonitis in cats. It causes inflammation in the peritoneal cavity due to fluid buildup.

Is peritonitis in cats fatal?

Most types of peritonitis in cats are fatal if left untreated.

Featured Image:

Katie Grzyb, DVM


Katie Grzyb, DVM


Dr. Katie Grzyb received her Doctorate of Veterinary Medicine from Ross University in 2009. She continued her clinical training at...

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