What Are the Causes of Swollen Abdomens in Kittens?

A big belly on a little kitten could indicate big trouble.
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Kittens are wobbly bundles of fluff with big eyes and adorable meows. Sometimes a swollen abdomen adds to the overall roly-poly look of a little kitten, making him even more wobbly on his tiny feet. That big belly might look cute, but it could indicate an underlying medical condition.


Roundworms are common among cats, and they are frustratingly easy to transfer from one to another. Most adult cats show no symptoms of the invading creepy-crawlies, but young kittens don't have as much real estate inside to house larger infestations. As the population grows in the kitten's intestines, his abdomen starts to swell.

One sure sign of these freeloaders is dead worms in your kitten's vomit or litter box, but your vet can also examine your kitten's poop for signs of worm eggs. Soon after a few doses of dewormer kill the pests, you'll see their stringy corpses in your pet's litter box.


Kittens are much like baby humans. They tend to chew on things within reach that fit into the mouth. This can lead to the accidental swallowing of the item, which might become stuck in his stomach or intestines, causing an obstruction that causes abdominal swelling.

Additional symptoms -- such as trouble in the litter box, behavioral changes, and pain -- typically appear in cases of obstruction. An obstruction can turn fatal if not treated quickly, so see your vet to confirm your suspicions and for treatment.

Medical Problems

No one wants to think about horrible medical conditions when playing with an adorable kitten, but nature can be cruel. Unusual belly swelling could indicate growing tumors, or abnormal swelling of his internal organs. Feline infectious peritonitis, or FIP, is a fatal disease that causes fluid retention in your kitten's abdomen and puts pressure on the lungs that prevents proper breathing. Blood, urine and other nasty fluids can collect in your kitten's abdomen because of tearing in the urinary tract, infections, or other internal injuries.

Watch for changes in behavior, appetite or litter box usage to determine the possibility of a deeper, more sinister medical problem.

When to See Your Veterinarian

Although it's possible your kitten is simply a little piggy who likes to keep his belly a bit too full, in most cases a swollen abdomen requires attention to keep your little fluff ball healthy. Because of their immature immune systems, kittens can take a turn for the worse, quickly and without warning.

Do not adopt a wait-and-see attitude for your kitten's swollen belly. Note any additional symptoms, and visit your veterinarian for a full checkup. If caught early, many medical conditions are resolved easily with proper treatment, leaving your kitten healthier than ever.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.

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