Do Worms Make Cats Have Big Stomachs?

A large belly may indicate worms or another medical problem.
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Roundworms are a common parasite found in cats, and their presence can cause various physical and behavioral changes in your pet. Most parasitic infestations don't result in an extended belly, but there are exceptions -- and in those cases you must take action quickly to eliminate the worms.

How Cats Get Roundworms

Roundworms are persnickety little parasites and the eggs only hatch when they find their way inside specific hosts, such as cats, dogs and even humans. Cats get roundworms by swallowing the eggs, either from an infected mother's milk, eating infected prey or walking through infected soil or poop and then grooming. After the eggs hatch in the cat's intestines, they see the sights by making a little journey through the cat's other organs and muscles as they mature. The mature worms will then return to the intestines, where they live their lives leeching nutrients from their host and making eggs.

Symptoms and Complications

In small infestations, you may not notice any difference in your cat at all. It's when the population grows into an internal version of New York City that your cat will start suffering from her uninvited guests. Large worm populations leech more nutrients from your cat's system, leaving her malnourished and looking unwell. These large groupings can make her belly look swollen or become so entwined that they cause a blockage in her intestines.


Getting rid of roundworms is fortunately simply a matter of giving your cat the proper deworming medication to snuff them out. Once they've gone belly up, the wormy corpses will pass through your cat's digestive tract, ending up as a stringy mass of spaghetti-like icky-ness in your pet's litter box. In cases where the population is too large or compacted, your vet may need to perform surgery to remove the squirmy interlopers.

Other Possible Causes

A big belly on your normally sleek kitty does not necessarily mean she's harboring a mass of squatters in her gut. Other medical issues could be at play instead, such as a tumor, weight gain from hypothyroidism or fluid retention. Your cat could also just be overweight if she's eating more than she's exercising. A sudden large belly should be investigated to find the culprit, so seek the help of your vet if you notice your kitty looking larger around the midsection than usual.

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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