Cat & Kitten Swollen Belly: Causes, Diagnosis and Treatment

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Cats can have swollen bellies for a variety of reasons. Potential causes for a cat or kitten swollen belly include organ enlargement, fluid or a mass in their belly, intestinal parasites and weight gain. In some cases, your veterinarian might be able to identify the cause of your pet's swollen belly through a physical exam alone. In most cases, however, your cat will need to undergo additional testing.

Keep reading to learn more about common causes of a cat swollen belly.

Organ Enlargement

Numerous organs in the abdomen can become enlarged and result in a swollen belly.

Liver, Spleen or Kidneys

Enlargement of the liver, spleen or kidneys can result from both benign and malignant types of cancer (either through invasion or development of a solitary masses), certain types of infections (especially fungal diseases), accumulation of inflammatory cells, or a response to disease elsewhere in the body.


An enlarged bladder and the inability to urinate can be signs of a urinary blockage, a potentially life-threatening condition. This condition is more common in male cats, but can also occur in females.

Gastrointestinal Tract

The gastrointestinal tract can become filled with gas, fluid, foreign material and even food, resulting in the appearance of a swollen belly. The most concerning of these is if there's something in the gastrointestinal tract resulting in a blockage.


If a female cat isn't spayed, the uterus can become enlarged during pregnancy or can enlarge with fluid or pus. The latter can be life-threatening. Note that after spay surgery, cats may have temporary swelling of their bellies if they're too active post-surgery or if they have a reaction to the stitches. This is why it's important to ensure your pet rests during recovery from surgery and if you notice a swelling is starting to develop, you should contact your veterinarian.

Fluid in the Abdomen

Moderate to large amounts of fluid in the abdomen can result in a cat or kitten swollen belly. Usually, if this is the case, the vet will be able to observe a fluid wave when they touch the area.

Fluid in the abdomen can be a result of numerous diseases:

  • Hemorrhage: Bleeding into the abdomen can be caused by bleeding tumors, trauma to internal organs, decreased platelet numbers or platelet dysfunction and the ingestion of a specific rat poison called an anticoagulant rodenticide.
  • Cancer: Cancer can cause fluid, and potentially blood, to accumulate in the abdomen.
  • Heart failure: Right-sided heart failure can lead to the inability to pump blood out effectively and result in a buildup of fluid in the abdomen. Any concern for heart failure should be considered an emergency and warrants prompt evaluation.
  • Low protein: Decreased production of proteins commonly occurs secondary to liver failure or disease of the kidneys or intestinal tract. When protein levels are too low, blood vessels in the body can become leaky and cause fluid to build up in the abdomen and other parts of the body.
  • Inflammation: Pancreatitis, among other diseases, can cause fluid buildup and inflammation in the abdomen.
  • Viral disease: Feline infectious peritonitis, a viral disease in cats, commonly results in fluid in the abdomen and the appearance of a swollen belly.
  • Rupture of a hollow organ: Considered an emergency, a tear in the urinary bladder, gallbladder or gastrointestinal tract can result in leakage of the respective organ's fluid contents into the abdomen. This can occur secondary to conditions including bladder stones and obstructions of the gallbladder or intestinal tract.

Intestinal Parasites

The presence of gastrointestinal parasites can make a cat look potbellied, notes the Cornell Feline Health Center. This is more commonly the cause of a kitten swollen belly as kittens are more likely to have large worm loads. Your vet can determine the presence of intestinal parasites by examining your cat's feces. Treatment normally consists of an oral medicine.

Ginger baby cat sleeping on a chair arm

Abdominal Mass

A mass associated with one of the many abdominal organs can result in a cat swollen belly. This is more common in adult cats. An abdominal mass can be benign or cancerous. Testing is necessary to obtain a specific diagnosis.

Based on the location and type of mass, treatment may involve surgery to remove the mass, chemotherapy or monitoring and supportive care with medications.


If your kitten or cat has a swollen belly, evaluation and diagnostic testing is needed to identify the cause of the swelling. Common diagnostic tests for a swollen belly include full bloodwork, urinalysis, an abdominal ultrasound and/or X-rays, chest X-rays, fluid evaluation and a biopsy (if a mass is present). Sometimes, more specific infectious disease or organ testing is necessary. The testing your vet recommends will be tailored to your individual pet's case.

Treatment of a Cat Swollen Belly

Treatment of a cat or kitten swollen belly is based on the underlying cause and can include — but is not limited to — removing fluid from the abdomen, medication and/or surgery. With any treatment plan, it's essential to monitor your pet and follow up with your veterinarian if you notice any behavioral or physical changes. If you are ever concerned about your cat looking potbellied, the simplest thing you can do is call your veterinarian and get their expert opinion on what to do next.

Contributor Bio

Jessica Seid

Jessica Seid

Jessica Seid is an emergency veterinarian practicing in the New England area. She is graduate of North Carolina State College of Veterinary Medicine and has been in the field for 10 plus years. When not at work helping her patients, she enjoys spending time with her husband, daughter and their French Bulldog.

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