Categories: parasitic worms

How do I know if my cat has worms?


The first point to make is that it’s probably sensible to make a presumption that your cat has worms if she is an indoor/outdoor cat. She’s likely to hunt and eat mice and in doing so ingest worms. The particular worms I am referring to are roundworms (ascarids). They are the most common worm parasite in cats and there are two common species.

They occur in 25-75% of adult cats. It is reasonable to make a presumption that outdoor cats have this worm because they ingest the eggs by (1) contact with the soil where the eggs are and licking their feet or (2) eating a host animal such as a mouse in which the encysted larvae lives. If the cat spends lots of time outside and hunts a lot she may acquire a heavy infestation.

Also there is a greater likelihood of picking up fleas if your cat is an outside cat. If your cat has fleas it is likely she’ll have tapeworms because the flea carries immature tapeworms in their intestines. The cat eats a flea when grooming and therefore ingests the tapeworm.

Hookworms are not as common in cats as in dogs but again can pick up the parasite through their feet by the parasites penetrating the skin or rarely through eating mice which are hosts to the larvae.

You can see that outdoor cats are quite likely to have worms and therefore a monthly treatment is advised.

My cat lives in a garden enclosure and no longer eats prey. I don’t give him deworming pills. This is a personal choice and some people would say a bad choice.

How do I know if my cat has worms? Signs

Other than a sensible presumption as mentioned above, there are some signs.


Diarrhoea, anaemia, weight loss and getting weaker. If the infestation is heavy the cat’s faeces may be bloody and dark (tarry-black). A diagnosis by a vet is made by seeing eggs in the cat’s faeces.


Heavy infestation: pot-bellied, thin, severe illness and possible death. Vomiting, diarrhoea, anemia, pneumonia. Stool or vomit may contain the worm. They look like earthworms or moving strands of spaghetti.


Tapeworm segments can be seen on the cat’s bum. They may move if moist or look like rice when dried up. These segments are passed in the faces. They might also be on the cat’s stool.

Human health consideration

There is also a human health issue worth noting. Roundworms can cause a disease in people: visceral larva migrant. It is one of the top zoonotic diseases. The primary culprit is the dog version of the worm: Toxocara canis but Toxcara cati can also cause human disease. Children are most at risk because they like to put things in their mouth even earth.

When a person eats a roundworm egg the larvae develops in the person but they don’t develop into worms but wander around the internal tissue of the person causing general illness such as fever, anemia, pneumonia and other illnesses.

Migrating larvae can get into a person’s eye causing ocular larva migrans which can lead to the loss of an eye.

How do cats get roundworms?

Domestic and feral cats get roundworms by ingesting the eggs. They ingest eggs in various ways, perhaps by being in ...
Read More

Pictures of cat tapeworm and tapeworm segments

Here is a collage of cat tapeworms and tapeworm segments that I have prepared because people search for 'What do ...
Read More

Europeans do not deworm their cats often enough

The cat roundworm Toxocara cati can infect humans as well. In other words your cat could transmit a roundworm infestation ...
Read More

Picture of giant, gross kidney worm that infected a dog but cats can get them too

This giant parasitic worm is gross and they do sometimes inhabit domestic cats! The size of it. It is hard ...
Read More

How do I know if my cat has worms?

You should be concerned that your cat might have worms if he or she is an indoor/outdoor cat and enjoys ...
Read More

Domestic cats eat grass to purge parasitic worms from their gut

There has been a long discussion on the internet about the reasons why domestic cats eat grass. Many years go, ...
Read More

Relocation of shelter animals transports heartworm as it is not always tested

The relocation of shelter animals often by air is commonplace in America. It's a great idea as it leads to ...
Read More
Please comment here using either Facebook or WordPress (when available).
Michael Broad

Hi, I'm a 71-year-old retired solicitor (attorney in the US). Before qualifying I worked in many jobs including professional photography. I have a girlfriend, Michelle. I love nature, cats and all animals. I am concerned about their welfare.

Recent Posts

Japanese shopowner replaces ceiling tiles with transparent ones for their cats

This is a cool solution for a cat guardian and shopowner who wants to allow…

4 hours ago

600 rescue cats and dogs in a Hercules C-130 plane in historic flight

The charities involved have shipped 600 rescue cats and dogs from Hawaiian animal shelters in…

5 hours ago

Spot the witches hat in this bank of feline faces at night

A Halloween puzzle to kill a few minutes. This is what a witches hat looks…

6 hours ago

Domestic cat’s highly-acidic digestive system

The domestic cat's digestive organs quite closely resemble those of humans. Working backwards they are…

18 hours ago

It’s National Cat Day in the US so what can I do about it?

National Cat Day was started to highlight cats at cat rescue shelters and to celebrate…

22 hours ago

Chicago cat shelter sells groups of feral cats for up to $600 to combat city’s rat problem

The CNN video tells us that Chicago has the worst rat problem in America. A…

1 day ago