Worms in cats


While it is wrong to say that worms do not harm cats, it is accurate to say that many cats with worms show next to no symptoms. It is still necessary to de-worm your cat, even if it shows no signs of worm infestation, especially if it is a hunter; rodents will often pick up worms from eating at faeces and the cycle will be re-established. Kittens can pick up worms when feeding from the mother; so many kittens arrive at their new home already infested with roundworm.

Types of Worm

There are two types of worm which are common in cats, tapeworm and roundworm – hookworm, a third type, is so rare as to not really need discussion. The generic name tapeworm refers to two different kinds which are spread in different ways. Both kinds are a segmented worm, which sheds its eggs in one of the segments. These can be seen sometimes around the cats anus; they look like grains of rice. They are also sometimes visible in the cats bedding.


The most common tapeworm, Dipylidium caninum, is transmitted by fleas when the larvae eat the worm eggs and then the cat eats the larvae when grooming itself. This means that eggs shed by one cat with worms can be easily picked up by another. It therefore has to be assumed that any cat with fleas will also have tapeworm. The other kind, Taenia taeniaeformis, is spread by the hunting of rodents. This kind is commonest in cats which hunt – so if you have a little ‘present’ on the doormat every morning, deposited there by your cat, it would be wise to de-worm it frequently.


Roundworm – the most common form is Toxocara cati – is a non-segmented worm which sheds eggs which can live outside the animal for years and then hatch when ingested. They can be passed on to another cat if it eats an infected rodent. This roundworm can also be passed in the milk of a feeding mother and this is why it is important to worm kittens regularly as soon as they are weaned, using a suitable medication.

Signs the Cat’s Worms are out of Control

Most cats can tolerate an infestation of worms with few or no ill effects, but occasionally the worms build up to such numbers that the cat can become quite ill. As long as you are sure from external signs – eggs around the anus or even whole or partial worms visible in faeces or vomit – that worms are the cause of your animal’s symptoms, it is possible to dose them with a proprietary worming preparation. It is still a wise precaution to take the animal to the vet, though, as the worms may have taken hold because the cat is under par because of an underlying condition which has allowed these opportunistic parasites to gain the upper hand.

Weight Loss

 A cat with an overwhelming infestation of worms will have weight loss; diarrhoea and vomiting (often containing worm segments or whole worms); irritation around the anus, leading to excessive cleaning and therefore re-ingestion of eggs and finally, mostly in the case of kittens, failure to thrive. Worming preparations are fairly slow to work as they disrupt the worms’ lifecycle, so a visit to the vet is really a good idea.

Are Worms Dangerous to Humans?

Tapeworm infestation of children used to be a common occurrence but is now almost unknown, with better hygiene and parental vigilance. It is possible for a child (normally not an adult) to become affected seriously if they ingest a roundworm egg, as the larval form is mobile around the body and may travel to and damage the eye. It is vital to dose cats against worm infestation, not only for the general good of the animal, but also to make sure that this risk is minimal.

Worming your Cat

Worming your cat used to be a very stressful experience, with the need to give tablets at timed intervals and everyone who has ever owned a cat knows how they hate to take tablets. More products are on the market now which minimise the animal’s distress and worming can now be as simple as a drop of liquid on the back of the neck. For a nervous cat (or nervous owner!) this is probably the administration method of choice. The important thing to remember, no matter what method is used, is that worming should be done regularly – wiping out an infestation is not permanent, it simply means that that particular generation of worms has been destroyed. These very persistent and opportunistic creatures will re-infest if the cat is not wormed prophylactically at regular intervals, which will depend of the animal’s age.


If worming kittens or a nursing mother, particular care should be given to the choice of worming product as not all are suitable. Products containing fenbendazole are usually the best choice although this particular drug is not yet available in ‘spot-on’ form. It is a defence against tapeworms and roundworms, though, which makes it easier to administer to small kittens as you won’t have to give double doses. It is also effective against lungworm. Praziquantel is specific against tapeworms and is often paired in the medication with pyrantel, which is effective against roundworm. As a pair, these drugs are found in ‘spot-on’ types of product and so are very easy to give, making regular dosing an easy option. Selamectin is another specific against roundworms which has the added bonus that it is also a treatment for ear mites and mange.


Prevention is very simple and can be summed up in one sentence; worm your cat regularly with a product that deals with tapeworms and roundworms and they will not be a problem. If only dealing with every possible cat problem could be this easy!


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