Feline Worming

Tapeworms and roundworms are the two most common types of internal parasites found in cats. In order to best understand why and when you should treat your cat it is helpful to review a few facts about these very well adapted parasites first.


Adult roundworms (Toxocara cati, Toxascaris leonina) are spaghetti-shaped, pinky-white worms that can measure up to 10-16cms in length and live in the small intestine of the cat. They may occasionally be vomited up or seen in the faeces and if alive, often appear tightly coiled like a spring.

Your cat can become infected by inadvertently ingesting these eggs when grooming the coat after rolling or digging in the soil, or eating food contaminated with soil.

Your cat can also be infected by eating a mouse or a bird that has also accidentally ingested a worm egg, and as a result carries the infective larvae.

Additionally, Toxocara cati larvae when migrating to the intestine in an adult cat become dormant in the tissues along the way. When a mother cat gives birth, these larvae will resume their migration but end up in her mammary glands where they pass in the milk to the kittens during suckling. This process ensures that virtually all kittens will be infected with T.cati roundworms from a very young age.


The two species of tapeworm likely to infest your cat are Dipylidium caninum, which is also found in dogs, and Taenia taeniaformis.  The adults of both species are white flattened ribbon like worms measuring up to 30cm in length.

Whilst you are most unlikely to see the whole worm unless it is vomited up, you are very likely to see these newly-passed segments moving around in the fur on the animal’s hindquarters, or on the faeces.

The life cycle of Dipylidium is closely associated with the life cycle of the flea.  The eggs of Dipylidium are ingested by flea larvae in the environment, and then form an infective cyst in the abdomen of the adult flea. The cat or dog becomes infected when accidentally ingesting an infected flea during grooming.  In contrast, the eggs of Taenia are ingested by mice and rats and form cysts in their internal organs. Cats are infected when they eat the infected rodent. 

How do these worms affect my cat?

Worms do not cause your animal to eat ravenously, and are most unlikely to be a cause of weight loss in adult cats. Roundworms are most likely to cause symptoms in kittens in their first 12 months of life and severity of signs reflects the degree of worm burden and age of the animal.

Characteristic signs of an infestation include a pot-belly, stunted growth or weight loss and gastrointestinal signs such as vomiting and diarrhoea.  Heavy burdens of migrating worm larvae in young kittens may be associated with liver or lung disease, and heavy burdens of adult worms in the gut can cause intestinal blockage. Sometimes deaths will occur.

Tapeworms have not generally been associated with specific clinical signs in the infected cat or dog, but the segments leaving the anus may cause irritation which you will observe as the affected animal licking or scooting its bottom along the ground.

If your cat is passing tapeworm segments there will also be some degree of flea infestation in the environment

Can these worms infect humans?

The potential for humans, particularly children, to be infected with larval roundworms is of concern. Accidental ingestion of worm eggs by children putting soil-contaminated fingers or objects in their mouth may occasionally result in the migration of the larvae in their tissues, even though humans are not the normal host for this parasite.  Affected children may have no signs of illness, or they may have severe symptoms depending on the numbers of larvae or the organs affected. Maintaining a regular worming program in family pets, covering sandpits between uses, and teaching children basic personal hygiene are practical measures to decrease their accidental uptake of roundworm eggs from the environment. Humans do not harbour the adult worms.

How often should I worm my cat?

•  Pregnant/nursing cats: treat after the 3rd week of pregnancy and then every 3 weeks until the kittens are weaned

•  Nursing kittens: treat at 1 week of age then every 2 weeks until weaning

•  Weaned kittens: treat monthly until 6 months (If you have just acquired a weaned kitten that has never been wormed, or is of unknown worming status, we recommend you treat it immediately and again 2 weeks later, then decrease to monthly intervals)

•  Cats 6-12 months: every 3 months

•  Cats12 months and older: every 3-6 months (the more regularly you treat for fleas, the less often you need to treat for tapeworm)


Purchase worm treatments where you can receive informed and accurate advice on which one is best suited for your requirements. Our staff are trained and experienced to help you with selection, tips on administration, advice on frequency of use and dosage.

•  Tablet formulations are available as narrow-spectrum, which treat for roundworm only, and broad-spectrum (all wormers) which treat for roundworm and tapeworm

•  A narrow-spectrum treatment is suitable for use in kittens between birth and weaning, or pregnant/nursing cats, where treatment for tapeworm is less of an issue

•  Broad-spectrum tablets tend to be larger and difficult to break down to an appropriate dose and manageable size for young kittens

•  Some brands of spot-on flea treatments will claim they treat worms as well, but they treat roundworms only.  This means they are entirely suitable as the only worm treatment for young kittens, pregnant/nursing cats and regularly-flea-treated indoor cats, but regular additional tapeworm treatment should be given to adult outdoor/hunting cats or cats in environments with troublesome flea problems.

If you have any questions, need assistance with selecting an appropriate worm treatment or administering the medication to your cat VetEnt staff will be happy to help. 

Click here to download a printable version of this factsheet.





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