A kitten outside the litter box, looking embarrassed and ashamed.
A kitten outside the litter box, looking embarrassed and ashamed. Photography ©ysbrandcosijn | Getty Images.

Roundworms in Cats — Signs, Causes and How to Treat Them

Roundworms in cats are a pretty gross but — unfortunately — fairly common condition in kitties. Even indoor cats can get roundworms! Here's what to know.


It can be positively cringe-worthy — and maybe even a little embarrassing — to find out your cat has worms. I know from experience, as I will never forget the time I found a little white roundworm, which almost looked like part of a rice noodle, squiggling around the base of my then-kitten Salvypoo’s tail. In all honesty, I wanted to hide under the bed and pretend I’d never seen it. As scary as they sound, roundworms in cats are actually extremely common — in fact, most cats will get roundworms at least once in their life, most often as kittens. Fortunately roundworms in cats are fairly easy and affordable to treat as well as prevent. Here’s what you need to know.

Symptoms of roundworms in cats

A closeup of a surprised cat with his ears back.
Are those … worms coming out of your cat’s bum? What are the signs of roundworms in cats? Photography © perets | E+ / Getty Images.

Spotting symptoms of roundworms in cats can be somewhat challenging. If your cat has a small number of worms, no symptoms may be present, but in general a cat with roundworms may experience lethargy, vomiting, abdominal swelling or a potbellied appearance (especially in kittens), weight loss or failure to gain weight, dull coat or diarrhea.

Kittens in particular may vomit up roundworms or pass them in the litter box. If you suspect your cat has roundworms, you might spot the distinctive, spaghetti-like parasites in her feces. In extreme cases, roundworms in cats can cause intestinal blockage or coughing due to the migration of roundworm larvae into the lungs.

Causes of roundworms in cats

Cats often get roundworms by eating another small animal that was also a host, such as a mouse or other prey, though kittens may get roundworms through their mother’s milk. “Kittens get them from their mothers when they initially nurse,” says Dr. Tash Taylor of the Cat Clinic of Johnson County in Lenexa, Kansas. “[Roundworms] go through the normal life cycle and some will encyst in the muscle and come out when the mother is pregnant. These migrate to the mammary glands and are transmitted to the kittens the first time they nurse.”

Unfortunately, indoor cats are not immune to roundworms — it’s possible for a sheltered housecat to contract roundworms by eating an infected insect that has wandered into your home. Roundworms in cats can also occur if you track an egg in on your shoes and your cat ingests the egg while grooming her sweet little jellybean toes.

What cats are at risk for roundworms?

“The cats who are most at risk for roundworms are kittens and cats who hunt, but any cat can get roundworms from an owner’s shoe or by playing with bugs that drag their bellies on the ground and pick up the eggs,” Dr. Taylor says. “Outdoor cats get them from contaminated soil, hunting or playing with bugs.”

Diagnosing roundworms in cats

Diagnosing roundworms in cats requires a stool sample, which is mixed with a special solution that causes eggs to float to the top. This sample is then examined using a microscope to determine whether the eggs are roundworms. It may take a couple of veterinary visits and more than one fecal test to properly diagnose roundworms in cats, as not every stool sample contains eggs.

Treatment of roundworms in cats

Here’s the good news about roundworms in cats: Once you have a diagnosis, treatment is simple. Your cat will take an oral de-worming medication, which forcibly evicts the roundworms from your kitty’s intestines and allows her to once again become a host for more pleasant things, like Fancy Feast potlucks and afternoon nap parties. Both prescription and over-the-counter varieties are available. It might take multiple rounds of medication for your cat to be fully parasite-free.

Prevention of roundworms in cats

Though roundworms in cats can be an insidious foe, it’s easy to decrease the likelihood that you or your cat will become infected by keeping your cat’s environment clean, changing the litter box regularly and considering preventive medication, especially if your cat hunts or regularly goes outdoors.

“I recommend year-round Revolution or Advantage Multi for heartworm prevention,” Dr. Taylor says. “Both products are also labeled to de-worm for roundworms. If cats are on either product year-round, they shouldn’t have any problems with the parasites themselves or be able to transmit them to other animals or people. Roundworms are zoonotic (transmissible to people).”

Prognosis of roundworms in cats

Left untreated, roundworms in cats can be deadly. Severe infestations of roundworms in cats can cause anemia, intestinal blockages and rectal prolapse, all of which can be fatal.

In general, though, your kitty can expect to make a full recovery from a roundworm infection. Once she has completed treatment for roundworms, she can usually expect to live a healthy and normal life. Take my Salvypoo, for example: He is now 3 years old, weighs 15 pounds, has a lustrous striped coat and loves climbing the walls (I wish I were exaggerating). In short, he is the picture of health — and I’ve almost gotten over the shock of finding that worm in the first place.

Thumbnail: Photography ©ysbrandcosijn | Getty Images.

Read more about cat health and care on Catster.com:

8 thoughts on “Roundworms in Cats — Signs, Causes and How to Treat Them”

  1. Close to three years ago I took in a young stray cat. She had a nasty case of roundworms, not known at the time. Since that time, I have struggled to get rid of these things. Everywhere on the internet states how easy it is, but I do the recommended dosage of medicines from the vet, she'll test negative and then two months later she has them again. She doesn't go outside, my house is kept clean, there are no mice in the house and yet they keep returning. My vet is at a loss and says she'll likely need to go on medication permanently. I'm at a loss and extremely frustrated. I want my cat to be healthy and am doing everything I can. Is it possible that when she tests negative that perhaps the lab tests aren't picking up on subtle traces that grow into larger problems over the course of a month or two?

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  5. Antoinette M. Toni Myers

    I have a 6 mo. old male kitten, the last 2 days, he won’t eat; we have picked off 2 OR 3 ‘TICKS’ – I THINK. He has become very docile. How can we treat for Tick bites, can the Vet give him medicine for that, IF that is the case. The Vet we use is ‘not in’ until Monday.
    We have noticed him trying eat a little this eve. & is walking more, but there is something wrong, which might be the result of the Ticks on him. I was putting Tea Tree Oil on him to protect against ‘fleas or ticks’, but apparently, we will have to give him the ‘strong meds’ they sell to keep ‘fleas & ticks’ off of animals ! Can a cat get Lyme Disease like a person ? Thank you, sincerely,
    Antoinette M Myers

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