Both dogs and cats can be parasitized by worms at an early age. These parasites live at the expense of animals. If a dog or a cat are infected with only a few worms, they cause little damage. But in the event of a larger infestation, the worms cause a serious health hazard, with symptoms such as diarrhea, cramps, a dull coat and often weight loss. Some worms are also responsible for coughing problems. The main types of worms encountered in our domestic animals are Nematodes and Cestodes.


They are better known under the name “round worms”. The most common are roundworms, hookworms and capillaries. These worms have dimensions ranging from 1 to 6 cm on average. Contamination occurs through contact with faeces of an infested animal, through ingestion of meat from mice, rodents, birds; and for some worms, by direct penetration of the larvae through the skin.

The Cestodes

Better known under the name of “flatworms”, they are the Tapeworms. These worms can reach considerable dimensions : up to 50 cm. Their transmission is mainly through the ingestion of meat containing tapeworm cysts (rodent meat but also mutton or beef …) and by fleas and lice.

How do you know if your pet has worms?

It is not because we do not see worms in faeces that there are none!  The worms live quietly in the intestines where they attach to the mucosa. They only come off if they die, that is to say when there are too many of them, or after the administration of a dewormer, for example. These adult worms release dozens of eggs daily which will end up in the stool.  One way to find out if an animal has worms is to do a stool test.

When to deworm an animal?

All puppies and kittens should be dewormed as soon as they leave their mothers, two or three times in a row one month apart. For adult animals, a dewormer is recommended 2 to 3 times a year, with a product active against both roundworms and flatworms. Animals with fleas must be treated every month until the fleas have completely disappeared (to avoid contamination by flea-transmitted dipylidium).

Contagion to humans

In very rare cases, some worms can pass from dog or cat to humans and children. This is why good prevention requires regular deworming of pets.