Two types of worms commonly affect cats – roundworms and tapeworms. They are entirely distinct from each other and therefore their treatment and prevention methods are different.

ROUNDWORMS
Two species infect cats – Toxocara and Toxascaris (there is a Toxocara species which infects dogs but this is separate). They are called roundworms because they are round in cross section, like an earthworm. The adult worm looks like a piece of plastic covered wire, between 5 and12cm long, pale beige or grey in colour, and can be curved, or coiled into a spring shape.

LIFE CYCLE - The adult worms live in the cat’s intestines where they mate and lay eggs invisible to the naked eye. These are passed in the cat’s faeces and, in a warm, moist environment, develop to larvae. The larvae may be eaten when a cat eats a bit of soil along with its food, eats a bird or rodent which has swallowed a larva, or rolls in sand containing larvae, and licks his coat clean. Once swallowed, the larvae move from the intestines through the bowel wall and into the cat’s bloodstream. In young kittens, the larvae then travel through the liver to the lungs, from where they are coughed up and swallowed by the kitten again. They return to the intestines once more, in a more mature form. To make things even more complicated, some larvae do not complete the whole journey at once, but instead form a cyst in different parts in the cat’s body. The larvae start moving again when the cat becomes pregnant (if she is a queen), and travel to the milk glands. In males or other females, the larvae start moving again if the cat is ill for any reason.
Toxocara from dogs has been known to migrate through children’s bodies in the same way. Most never develop because they are in the wrong host, but very rarely a larva can reach the back of the eye and cause problems with the child’s sight. It is extremely rare for this to occur with Toxocara from cats

SIGNS – Roundworms do little harm in adult cats, although large numbers can cause diarrhoea and ill thrift in kittens. The worms are usually seen if the cat vomits, although they are not usually the cause of the vomiting.

WORMING – Worm your cat for roundworms every 3 months, or more often for kittens and pregnant queens – your vet can advise you.

TAPEWORMS
Two species of tapeworms affect cats – Taenia and Dipylidium. The adults are long and flat, made up of tiny segments. You will not usually see an entire adult – instead you see the individual segments at the cat’s back end.

SIGNS – the segments are seen crawling around the cat’s back end, out of its anus, or in the faeces. The segments are white and look like a grain of rice, those of Dipylidium will wriggle for a while before drying out on the cat’s coat, while Taenia segments do not move. The adults do not cause a problem to the cat but the passed segments may cause discomfort around the anus.

LIFE CYCLE - the segments detach from the adult when they are ripe and full of eggs, and pass out the body to continue their development. They need to pass through a secondary host before they can reinfect another cat – with Taenia this is a shrew, mouse or rabbit, with Dipylidium it is a flea or louse. The cat is then reinfected by eating the tapeworm cyst in the flea or rodent, and adult tapeworms form in the intestine.

WORMING – the adult worms can be controlled by giving suitable wormers, again every 3 months is ideal. Fleas must also be eliminated in the case of Dipylidium, as these are the secondary host. Some cats which are enthusiastic hunters may need treated more regularly for tapeworms, as each mouse eaten is a new source of Taenia – treat whenever the segments are seen.
Modern worming preparations available from your vet will kill both tapeworms and roundworms with one dose – these should be given every 3 months routinely. There are different forms of wormer – tablets, powders, liquids, injections and spot-on preparations. They do not all treat both types of worms, so always be advised by your vet, or read the instructions. If you have difficulty administering tablets or powders, then one of the other forms may be more suitable.
Humans cannot catch tapeworms from cats.

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