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Peritonitis in Dogs

The abdominal cavity is lined with a thin, watery membrane, called the peritoneum. When the dog's  abdominal cavity, also called the peritoneal cavity, is injured, the peritoneum becomes inflamed.

The severity of the inflammation depends on the type of injury the peritoneal cavity has undergone. Peritonitis is frequently a painful condition, and the affected dog will respond when it is touched on its abdomen.

Peritonitis can affect both dogs and cats. To learn more about how it affects cats, please visit this page in the petMD health library.

Symptoms and Types

• Fever
• Vomiting
• Abdominal pain
• Animal positions itself in a “praying” position for relief of pain
• Low blood pressure and signs of shock
• Increased heart rate
• Possible abnormal heart rhythm (arrhythmia)

Causes

• Peritonitis
  • Caused by the spread of a causative agent through the blood
  • Secondary peritonitis (caused by an injury elsewhere in the body)
• Common form
  • Caused by injury to the abdominal cavity or hollow organs
  • Bacterial or chemical contamination:
    • Opening of surgical sites
    • Penetrating abdominal wounds
    • Blunt abdominal trauma
    • Severe inflammation of the pancreas
    • Filling of the abdomen with pus
    • Liver abscesses (inflamed swelling with pus)
    • Prostatic cysts -- in males, inflamed swelling with pus from the prostate gland
    • Rupture of the gallbladder, urinary bladder, or bile duct

Diagnosis

Your veterinarian will perform a complete physical exam on your dog, including a chemical blood profile, a complete blood count, a urinalysis, and an electrolyte panel. You will need to give a thorough history of your dog's health, including a background history of symptoms, and possible incidents that might have precipitated this condition. The history you provide may give your veterinarian an indication of whether other organs are causing the condition or are being affected.

Radiograph and ultrasound imaging are critical for visualizing the presence of free fluid in the abdomen, free gas in the abdomen, and an abscess, if it is present. A fluid sample taken by abdominocentesis should be done so that a sample can be stored in a vacuum blood collection tube (EDTA tube) for laboratory analysis. If fluid cannot be recovered during an abdominocentesis, a diagnostic peritoneal lavage (stomach wash) can be done.

Treatment

Dogs with peritonitis should be hospitalized in the intensive care unit for fluid and electrolyte therapy. Your pet's diet will need to be changed to a low-sodium diet if an underlying heart disease is detected. If the dog is in need of nutritional support, a feeding tube can be placed directly into the digestive tract, or feedings can be administered by injection (parenteral). Once the dog has been stablized, your veterinarian will begin to prescribe and administer medication.

If your dog has a bacterial or chemical peritonitis, surgery will be required to resolve the condition. These are serious conditions, and many animals may die despite having surgical treatment. Bloodwork will be repeated every one to two days, or as your doctor deems necessary, while your dog is in the intensive care unit.

Living and Management

If your dog needs to undergo surgery, or if it needs time to heal from a trauma to the abdomen, allow it a quiet and safe space to recover, away from active children and other pets. During recovery, your dog will need to be given a diet that will not place stress on the abdomen.

Ask your veterinarian for advice on dietary changes you may need to make for your dog, and whether the changes need to be made for a short duration, or for the lifetime of your pet.