Heart Sac Inflammation (Pericarditis) in Cats


PetMD Editorial

Published Jan. 16, 2009

Pericarditis in Cats

If a cat's pericardium (the membranous sac surrounding the heart and roots of the vessels) becomes inflamed, it is a condition referred to as pericarditis. The pericardium is made up of two layers: a fibrous outer layer and a membranous inner layer that adheres closely to the heart. Within the sac is a layer of pericardial fluid made up of serum, a watery fluid that serves to keep the surfaces of the membranous sac and heart moist. The body's membranes will also secrete serum when they detect inflammation of the surrounding tissues and organs.

When either of the layers of the pericardium becomes inflamed, the natural reaction is for the membranes to produce more serum, which leads to an excess of serum in the pericardium. The build-up of fluid compresses the heart, placing too much pressure on it, and on the surrounding tissue, typically leading to more inflammation and further swelling.

Pericarditis can affect both dogs and cats. If you would like to learn more about how this disease affects dogs, please visit this page in the PetMD health library.

Symptoms and Types

Right-sided congestive heart failure is the usual outcome of pericarditis. Other symptoms include:

  • Anorexia
  • Lethargy
  • Fluid buildup in the abdomen
  • Difficulty breathing
  • Weak pulse
  • Increased heart rate
  • Collapse


May be diagnosed as idiopathic or agnogenic (meaning that it is not related to anything in particular, and is of unknown cause). The only apparent problem may be that there is excess fluid buildup, with seemingly nothing else to explain the disease. Other common causes include:

1. Trauma

2. Bacterial infection:

  • E. coli: systemic infection, typically gastrointestinal
  • Streptococcus: various types, attacks respiratory system
  • Staphylococcus aureus: infection of the skin, nose, and throat
  • Actinomyces: invasion that causes lumpy tumors in the neck, chest, abdomen, and around the face and mouth; also called 'lumpy jaw'

3. Viral infection:

  • Feline infectious peritonitis (FIP), or feline coronavirus: a serious disorder that often attacks the abdomen, kidney, or brain

4. Fungalinfection:

  • Cryptococcus: transmitted through infected soil

5. Parasitic infection:

  • Toxoplasmosis: a parasitic infection that attacks the central nervous system; fever, seizures, and respiratory distress are symptoms of this infection; mainly occurs secondary to a condition that is weakening the immune system

6. Protozoal infection



Your veterinarian will perform a thorough physical exam on your cat, including a blood chemical profile, a complete blood count, a urinalysis, and an electrolyte panel to look for an underlying cause, or systemic illness. If bacterial based pericarditis is suspected, your veterinarian will take a fluid sample of the pericardial effusion for aerobic and anaerobic culture. That is, examination of tissue that lives with oxygen, and tissue that lives without oxygen.

Thoracic radiograph images (X-rays of the chest), and echocardiogram images are essential for an accurate visual diagnosis. Other, less sensitive tests which might still supply useful information about the heart are cardiac catheterization, where a tube is inserted into an artery or vein in the arm or leg, and then threaded up into the chambers of the heart; and electrocardiogram, which records the heart's electrical muscle activity. Both tests measure functionality: blood pressure and flow, rhythm, and how well the heart muscle is pumping.


Treatment will depend on the underlying cause of the pericarditis. All cats with this disease will need to be hospitalized in an intensive care unit. Chemotherapy will be prescribed if there are cancerous neoplastic (abnormal tissue growth) conditions, and bacterial infections will be treated with the appropriate antibiotics. A pericardectomy surgery to remove part of the pericardium may also be necessary.

Living and Management

This condition will sometimes reoccur. If signs of illness return at anytime after taking your cat home, call your veterinarian immediately for advisement.

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