Throwing Up Worms

I recently had contact with a girl whose aunt has a 5-year-old month kitten. Sadly, the kitten was throwing up worms, and her aunt wasn’t very pleased what she saw when she was cleaning up the vomit. Worms. When a cat is throwing up worms, this can usually mean one thing: Round worms. It’s important to take your cat to the vet immediately!


rwRoundworms (also called Ascarids) are intestinal parasitic worms, there are many various round worms, but the two species that are often found in cats are Toxocara cati and Toxascaris Leonina. T. Cati is more found in cats. The worms feed on whatever they can find intestinal, competing with the host for food. Adult roundworms live in the stomach and intestines and can grow to 5 inches (13cm) long. The eggs are protected by a hard shell. They  can live for months or years in the soil. They become infective in three to four weeks after being passed out in poop.

The larvae of T. Cati are capable of migrating in tissue. Eggs that get in the cat orally hatch in the intestines. Larvae can also be carried to the lungs by the bloodstream and from there become mobile and crawl up the trachea where they are then swallowed. This may cause coughing and gagging. The eggs return to the intestines to become adult worms. This migration often happens with kittens.

In Adult cats only a few larvae will return to the intestines. The other eggs stay in tissue ‘sleeping’. During nursing, these ‘sleeping’ larvae are released and the infection starts all over again when they are transmitted from mother to kitten through the milk. A cat that is nursing, may not pass eggs in her stool, but in her milk instead. So even though a ‘poop’ exam is negative, it might still be there. Therefor you should deworm both mother and kittens starting about three weeks of age. The eggs and larvae of the roundworm can be find in the following places: Kitty litter, feces, vomit, dirt and mother’s (cat) milk.

The cat passes eggs in her stool or larvae in her milk (1). The larvae infect her nursing kitten. Eggs from the stool (2) develop into larvae (3) and are eaten by rodents (4). The cat then eats the rodents while hunting. If the ­larvae pass through the kitten before maturing, the mother cat can also reinfest herself while grooming her kittens. –

Life Cycle Of The Roundworm

T. Cati

  1.  Eggs are passed in the stool and at this stage they are infective.
    Once they are in, they develop into the ‘second stage larvae’. At that time they become infective.
  2. The cat ingests the egg containing the infective larvae.
    Once the egg is inside, they hatch in the intestinal tract. The larvae might also migrate to the liver and other organs.
  3. In the liver they develop into the third stage.
  4. Then they enter the bloodstream and into the lungs. Once they are into the lungs they develop into the fourth larvae stage.
  5. They are coughed up into the throat and swallowed. Re-entering the intestinal tract for a second time.
  6. When they are in the intestinal tract again they mature and begin to mate.
  7. The female worm lays her eggs which are passed in the stool.
  8. Cycle beings all over again.

Some of these become encysted in the tissues where they are inactive. When a cat is wormed, the worms in the intestines are killed. They are not able to complete their life cycle in rodents, but if cats eat infected prey, they can become infected.

T. leonina

  1. The eggs of Toxascaris leonia are passed in the stool where they develop into the second stage and become infective.
  2. The larvae are consumed by the cat.
  3. They hatch in the cat’s intestinal tract.

There is no trans-mammary transmission with Toxoscaris leonia.


How Do Cats Get Roundworms?

There are three ways your cat can get infected by these nasty worms. All of which when the cat consumes the infective eggs. It is possible for larvae to be encysted in the tissues from an earlier infection.

  • When a cat is infected with roundworm, some larvae migrate to other tissues in the body.
  • Pregnancy  re-activates these larvae and are passed onto the kittens via the mother’s milk.
  • Rodents can act as intermediate hosts to roundworm, so when a cat is hunting and kills a rodent who has roundworms, he will become infected.
  • Cats ingest roundworm eggs containing infective larvae from the environment such as soil, or when they come into contact with the stool of an infected cat.
  • Worm ova can be ingested when a cat uses infested kitty litter and then cleans her paws while grooming.
  • Biting and ingesting fleas can also lead to a case of roundworms.

Can I Get It?

Yes you can! So as soon as when you find out your cat has roundworms. It’s important to keep them away from your other pets and children so they won’t get it.

The worms can cause a disease in humans called ‘Visceral larva migrans‘. This is considered to be a serious health problem. Children are more affected than adults and often have a history of eating dirty. Outdoor sandbox should be covered when not in use to prevent cats from using them as litter box. With VLM the larvae migrates to the various organs and cause an inflammatory immune response which leads to damage to the organs.

Then there is ‘Ocular Larva Migrans‘. This is the result from the larvae entering the eyes. Causing inflammatory response which can lead to damage to the eyes. In worse cases it can cause blindness.

Read this article at for signs in humans.

Signs Your Cat Has Roundworms

  • In kittens, a heavy infestation can result in severe illness or even death. Those infected kittens seem thin and have a pot-bellied look.
  • Poor coat condition
  • Not a good appetite
  • Sluggish behavior
  • Less grooming
  • Diarrhea
  • Vomiting (if infected, worms can be seen in the vomit (They look like white earthworms or strands of spaghetti that are alive and moving.))
  • Severe cases can lead to pneumonia and intestinal and bowel blockage (if the infestation is severe).

Your vet will exam your cat and give you the medication your cat need. Don’t forget to deworm your cat!

Preventing Roundworms

  • Cat_Hlth_RoundWorm_97787440Regular worming, especially if your cat is an outdoor cat and a very good hunter. Or do not allow your cat to hunt.
  • Often clean the litter box and remove stool.
  • Keep new cats separated from the rest of your cats until you can have them checked for worms.
  • Make sure your cat doesn’t get fleas.
  • Follow your veterinarian’s instructions carefully.

Deworming the queen before or during pregnancy does not prevent all infestation of kittens after birth. Medications do not end encysted larvae. –

If you notice spaghetti-like strands in your cat’s vomit, be sure to call your vet immediately. If you also have children, it is a good idea to have their doctor check them for signs of roundworms as well.

Resource – Visceral larva migrans & Ocular larva migrans.

Pictures by,,

17 Responses to “Throwing Up Worms”

  1. angelswhisper2011

    Little Binky had roundworms, when she was a kitten. She was nearly killed by them, because they were already in her lungs. The first time when I saw her throw up all these rubber bands, I startled to death, because they began to move, when I picked them up. Yikes!

  2. Elizabeth Benoit

    Very informative as usual. My daughter’s recently rescued kitten was infected with worms. Luckily, the vet was able to treat the kitten and save his precious life.


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