The organs themselves can swell, causing visual enlargement of the abdomen. Benign or malignant tumor growths on organs or glands can also lead to an expanded belly. Older cats or unwell cats can lose muscle mass which can make the abdomen look enlarged. During pregnancy, a female cat’s uterus will expand rapidly. Determining the reason for abdominal distention is something that needs to be done by a veterinary professional, as certain issues can be life-threatening.

The abdominal cavity houses many of a cat’s vital internal organs. It is a large cavity that is lined with a special membrane. This cavity can become enlarged or swollen when various substances build up within it. This distention can be due to excess fluids such as blood, water, urine or pus that have leaked from organs in the body. The abdomen can also swell from air, gas, fat or an internal obstruction.

While the most obvious sign for abdominal distension is a visibly swollen belly area, noting all other signs may help to diagnose the underlying cause of the enlargement. Signs that commonly occur with abdominal distension include:

Because there are so many organs present within the abdominal cavity, many different conditions can cause an enlarged abdomen. The underlying cause can be narrowed down by the abnormal substance filling and expanding the abdomen. Probable causes include:

Bring your cat’s full medical history to your veterinary appointment. The veterinarian will perform a complete physical examination to determine whether the abdomen is filled with fluids, air, or solids. You will be asked about the onset of signs along with your cat's diet and urination patterns. An X-ray may be needed to identify enlarged organs or tumorous growths within the abdomen. A chest X-ray can evaluate heart issues if they have been suspected as the cause of distension. If too much fluid is present for clear X-rays, an ultrasound may be performed instead.

Abdominocentesis may be performed to remove a sample of abdominal fluid or air for further microscopic testing. This can reveal what type of fluid exists and can identify any bacteria present. Full blood work might be recommended, to run a biochemical analysis, including complete blood count, packed cell volume, and total protein test. The CBC can show anemia, infection or malignancy within the cat. Urinalysis may be performed to find abnormal substances in the urine. If a tumor has been found or enlarged organs are present, a tissue biopsy may be collected for histopathological examination. 

The function of internal abdominal organs should be tested. Urine may need to be collected over the course of 24 hours to measure protein leakage and determine if the kidneys are failing. An echocardiogram may be run to examine the function of heart valves. Fecal examination may be needed to identify parasites and worms inside the cat. Tests should be run to see if the cat is FIP, FIV or FeLV positive.

Appropriate treatment will vary depending on the individual diagnosis of the cat. If distension has been caused by bleeding, emergency care will need to be administered to stop the blood loss. 

As a treatment, abdominocentesis can be used to drain fluid or air causing breathing difficulties within the cat. This draining relieves pressure on the lungs and diaphragm.

Administering diuretic medication can help drain excess fluid.

If a rupture has been found in any of the organs, surgery may be needed to repair the organ to stop leakage of blood or urine into the abdominal cavity. General anesthesia is needed for this procedure.

The surgical removal of tumorous growths, diseased adrenal glands or of the entire uterus in the case of pyometra may be necessary to restore function to the cat’s body. Success of this surgery depends on whether progressed cancer or infection is present. If cancer exists, radiation therapy or chemotherapy may also be needed.

If a bacterial infection has been identified, an appropriate antibiotic can be administered to rid the body of the harmful bacteria. Antibiotics are also prescribed after operations to prevent infection from developing. Prescriptions generally last from one to four weeks.

Deworming Medication If parasites have been discovered in the cat, deworming medicine will be prescribed to eliminate the infestation.

If your cat has undergone surgery, follow all at-home care instructions given by the veterinarian. Monitor the incision site daily to ensure it is clean and free of infection. Do not allow your cat to lick or bite at its stitches. Limit activity until the healing process is complete. If surgical repair or benign tumor removal is successful, a cat may make a full recovery if it survives the surgery and healing process.

Bacterial infections and parasite infestation often resolve completely with appropriate medication. Pregnancy will resolve on its own within 63 days when kittens are born. If your cat suffers from obesity or food intolerances, your vet may create a specialized diet to follow. This diet should contain no fillers or chemicals. Increase your cat's activity to promote weight loss. If your cat has been diagnosed with FIP or gastrointestinal cancer, prognosis is much more guarded.

Abdominal distension can be symptomatic of a serious medical condition. To avoid high vet care expenses, secure pet health insurance today. The sooner you insure your pet, the more protection you’ll have from unexpected vet costs.