Swollen Belly in Cats

At a glance

Common causes of a swollen belly in cats can include:

  • Ascites
  • Food intolerance
  • Parasitic worms
  • Cushing’s syndrome
  • Pregnancy
  • Weight gain
  • Cancer
  • Feline infectious peritonitis
  • Gastrointestinal obstruction
  • Pyometra

Treatment: This will depend on the underlying cause.


The abdomen is located between the chest and the pelvis and it houses several important organs including the liver, spleen, kidneys, stomach, intestines, pancreas and bladder.

Also known as abdominal distension, there are several causes of a swollen belly (abdomen) in cats, the swelling may be due to fluid, a tumour, gas, obstruction, worms etc. Depending on the severity of the swelling, breathing may become difficult and you may find your cat becomes lethargic.



Also known as abdominal effusion, ascites (pronounced ass-eye-tees), is a condition in cats characterised by the accumulation of fluid in the abdominal cavity. There are a number of possible causes including liver disease, ruptured bladder, right-sided heart failure, and peritonitis.



Successful treatment relies on treatment of the underlying cause as well as managing symptoms. The initial goal is to make your cat comfortable which can include:

Abdominocentesis: Removal of the fluid within the peritoneal cavity via a catheter, will help to improve his breathing by reducing pressure on the diaphragm.

Diuretics: Furosemide promotes the production of urine which assists in flushing excess fluids out of the body. Care must be taken when using diuretics as increased urinary excretion can lead to hypokalemia (low blood potassium).

Cushing’s Syndrome

Cushing’s syndrome (hyperadrenocorticism) is an endocrine disorder caused by high levels of cortisol in the body either due to a tumour or medical administration. There are several causes which include administration of cortisone, adrenal or pituitary tumours.



If the disease is caused by the use of corticosteroids then the medication will be gradually withdrawn. This needs to be done slowly and carefully to give the adrenal glands the chance to begin functioning properly.

Generally, while drugs have been shown to be effective in dogs, this is generally not the case in cats.

Surgical removal of the adrenal gland(s) (adrenalectomy). If the disease is caused by an adrenal tumour in one gland, then only the affected gland will be removed.

If the disease is caused by a pituitary tumour then both the adrenal glands will be removed. Adrenalectomy is a risky and difficult operation, and once the adrenal glands are removed your cat will have to have replacement therapy with glucocorticoids and mineralocorticoids throughout their lives.

Feline infectious peritonitis

A usually fatal viral infection caused by certain strains of the coronavirus.


  • Abdominal enlargement
  • Difficulty breathing
  • Loss of appetite
  • Weight loss
  • Lethargy


FIP is almost always fatal, prednisone may be prescribed along with supportive care.

Dietary intolerance

Food intolerance is an adverse reaction to a food, one of its ingredients or additives. It differs from a food allergy in that there is no immune system involvement.


  • Nonseasonal itching, especially around the face and head
  • Hair loss
  • Vomiting
  • Flatulence
  • Diarrhea
  • Abdominal discomfort


Avoid the food which caused the intolerances is the best method of treatment. This may either be a homemade diet or a commercial one. If you are feeding a homemade diet it is important to ensure that your cat is receiving the correct nutrients in the diet.


Also referred to as malignant neoplasms or malignant tumours, cancer is the uncontrolled division of cells that normally should be restrictive in their growth. Tumours can be malignant (cancerous) or benign. Certain types of cancer can develop in the abdomen and can cause organ enlargement.


The symptoms of cancer can vary depending on the organ system affected but can include:


  • Surgery: Where possible, surgical excision of the tumour with a wide margin, it may also be necessary to remove lymph nodes closest to the tumour.
  • Chemotherapy: Several drugs that target rapidly dividing cells. Chemotherapy can shrink a tumour before surgery, after surgery to kill cancer to kill any cells left behind, or as a stand-alone treatment where surgery is not possible. In the latter case, the goal is to slow down the progression of the tumour.
  • Electrochemotherapy: An emerging therapeutic which shows great promise for the treatment of skin tumours. Chemotherapy drugs are poorly absorbed, but this treatment allows for better penetration by delivering electric impulsions into the tumour after administration of chemotherapy. More information can be found on this site.
  • Radiotherapy: A treatment that uses a radiation beam to target cancer cells. Radiotherapy can be used to treat cancers that cannot be surgically removed or after surgical removal to target any cancer cells which have been left behind.
  • Cryosurgery: For some cancers on the skin, liquid nitrogen is used to freeze and destroy target cancer cells.

Gastrointestinal obstruction

A gastrointestinal blockage refers to the blockage anywhere from the stomach (gastro) to the intestines. Thankfully gastrointestinal blockages are less common in cats than they are in dogs, however, they can and do occur. Blockages can develop anywhere in the small or large intestine, it may be partial or complete. If a full blockage occurs, food, water, and gastric juices can build up behind the site of the obstruction and eventually cause a rupture. Causes include hairballs, ingestion of a foreign body, cancer, twisting of the intestine, adhesions and heavy tapeworm infection.



  • Most cases of gastrointestinal obstruction require surgery. That includes tumours, hernias, twisted or telescoped intestines, ingestion of foreign object and pyloric stenosis.
  • Endoscopy to stretch strictures. If scarring has occurred, surgical removal of the affected portion will be necessary.
  • Surgical removal of dead intestinal tissue.
  • Anti-worming medication to treat tapeworm.


The belly of a pregnant cat will be noticeably larger from the fifth week of pregnancy. Some cats will experience morning sickness in the early weeks and may lose their appetite. The gestation period for a cat is 63-65 days (approximately 9 weeks). This varies between cat though, and anywhere between 60 to 70 days is normal.


  • Loss of appetite in some cats due to morning sickness
  • Enlarged belly around the fifth week of pregnancy
  • Pink nipples


The belly will return to its pre-pregnancy size after the delivery of the kittens.


Pyometra (pus-filled uterus) is a serious and life-threatening infection associated with a condition known as cystic endometrial hyperplasia (CEH). It used to be thought that female cats were induced ovulators, meaning ovulation occurs when the cat mates, however, it is now believed that the female ovulates spontaneously (without mating) and several ovulations may have occurred without the owner being aware.



  • Ovariohysterectomy (desexing/spaying) is the best option.
  • Antibiotics to control the infection.
  • IV fluids to treat dehydration.
  • Prostaglandin treatment if the cat is required for breeding. This causes contraction of the uterus and the cervix to relax, which assists in the evacuation of the pus. There may be side effects from the prostaglandin such as vomiting, diarrhea, restlessness, panting, shock.
  • Where possible, culture the pus so that the cat can receive the most effective antibiotics.
  • There is a chance that treatment will not be successful, and for pyometra to reoccur in cats treated for pyometra but not spayed.

Intestinal worms

Roundworms, hookworms and tapeworms are common parasitic worms that are found in the cat’s gastrointestinal tract and can cause abdominal distention, particularly in kittens or if the worm burden is high.


  • Pot-bellied appearance
  • Anemia
  • Pale gums due to anemia
  • Visible worms in the feces or vomit


There are several effective anti-parasitic treatments available to kill worms.

Weight gain

Last but not least is weight gain which can be caused by too many calories, inactivity or underlying medical conditions. Middle-aged to senior cats are more prone to weight gain as they become less active.

Symptoms: Weight gain and a decrease in activity. Obese cats will often have difficulty grooming.

Treatment: A veterinary supervised change in diet and increase exercise.


The veterinarian will perform a complete physical examination of your cat and obtain a medical history from you. He will want to know when you first noticed symptoms. He will need to perform some diagnostic tests, some of which may include:

  • Biochemical profile, complete blood count, and urinalysis to evaluate organ functions.
  • X-ray and/or ultrasound to look for cancers and evaluate the organs for enlargement.
  • Biopsy of abnormal growths to evaluate for cancer.
  • Fecal analysis to look for the presence of worm eggs.

Specific tests for Cushing’s syndrome:

  • ACTH stimulation test
  • Low-dose dexamethasone suppression test (also known as ACTH suppression test)
  • Urine Cortisol: Creatinine Ratio (UC:Cr): This tests levels of cortisol in the urine and is measured against levels of creatinine. If the level is normal, hyperadrenocorticism can be ruled out
  • ECG – To evaluate the heart function for abnormalities


  • Julia Wilson, 'Cat World' Founder

    Julia Wilson is the founder of Cat-World, and has researched and written over 1,000 articles about cats. She is a cat expert with over 20 years of experience writing about a wide range of cat topics, with a special interest in cat health, welfare and preventative care. Julia lives in Sydney with her family, four cats and two dogs. Full author bio