It can be alarming to discover that your cat has worms but it should not come as a surprise. All pets are affected at some stage in their life and many will be re-infected unless they are given regular, routine worming treatment. Except in rare cases, worms are unlikely to cause serious harm. Getting rid of worms is relatively simple and inexpensive so regular treatment is strongly recommended, particularly as some types of worm can be passed onto humans.
There are two important types of parasitic worm in dogs – roundworms and tapeworms. Roundworms can grow up to 15 cm long and are white in colour. As their name suggests they are round (like string), whereas tapeworms are flat (like ribbons). Tapeworms can grow up to 60 cm long.
Both roundworms and tapeworms live in the cat’s intestines along with two other types of smaller worm (similar to roundworms) called whipworms and hookworms. However, these rarely affect cats in the UK. In some countries there are parasitic worms that can live in the cat’s lungs, heart, stomach or bladder but these are rarely seen in Europe.
Intestinal worms help themselves to your cat’s food and can damage the gut causing loss of blood. Worms can also cause diarrhoea, dehydration and anaemia, and this may make your cat run-down and susceptible to other diseases. If there are a lot of worms your cat may cough, lose weight, have a rough, dry coat or a ‘pot-bellied’ appearance.
In kittens a worm infection can be more serious, causing poor growth and sometimes even death. If there are large numbers of worms the intestine can become blocked (although this is rare in an adult cat) and this may be fatal.
Roundworms grow in the intestine laying thousands of eggs which pass out in the faeces (droppings). The eggs can survive for months or even years in the soil and need to lie in the environment for some time before they can infect another animal. They find their way into a new host either directly, (when eaten by a cat) or indirectly, (after being swallowed by a rodent which is then eaten by the cat). Inside the rodent – and sometimes in people – the egg hatches inside the gut, burrows through the intestine wall and lodges as a resting larval stage somewhere within the body. Immature worms also survive in the tissues of an infected cat. Immature worms can be passed from a mother to her kittens in the milk.
Tapeworms are anchored by their head to the intestine wall and grow a continuous ribbon of segments, each packed with eggs. The segments gradually break off and are passed out in the faeces. These segments look like grains of rice and mamy wriggle like a maggot for a short time before they dry up (sometimes still attached to your cat’s fur). The most common type of tapeworm moves on to a new cat by way of fleas. Immature fleas pick up infection from cat faeces in the environment and cats are then infected if they accidentally swallow an adult flea during grooming.
There is also a less common type of tapeworm, which uses mice, other rodents and rabbits to complete its life-cycle. This parasite lies dormant in the muscle or other organs of a small rodent or rabbit and cats are infected if they eat these animals.
Apart from the general effects on health described above, signs of infestation are to be found in your cat’s faeces (droppings). Segments of tapeworm (looking like grains of rice) can often be seen in the faeces or in the fur around the tail base and back legs. Roundworm eggs can only be seen by using a microscope to examine the faeces.
There are some highly effective treatments which will kill worms. These are available as liquids, pastes, tablets or powder. However, not all the products are equally good and some work against certain types of worms and not others. Your vet will be able to advise you on which product is best for your dog.
Worms are so common that it is safe to assume that all kittens, cats with fleas, and animals which regularly catch wildlife will be infected. Kittens should be treated with wormers every two weeks, from four weeks to 16 weeks of age, and older cats should be treated about every three months. Some cats, e.g. hunting cats, will need more regular treatment than others. You should discuss with your vet the most appropriate treatment regime for your pet.
The common roundworm found in dogs is a rare but potentially serious cause of human disease. The larval stages of this worm burrow through the gut wall and become embedded somewhere within the body and can cause serious damage if they end up, for example, in the eye. There are occasional reports of the victim, usually a child, being blinded in one eye. However, the type of roundworm normally found in cats is much less likely to cause problems in humans and most of the parasites found in cats are unable to survive at all in people.
Apart from regularly worming your pets, there are a number of other measures which can stop worms being passed on from cat to cat, or from cat to people.
- If a cat uses your garden as a toilet clean up the faeces (droppings) and bury them (if your cat has not done so already) or put them inside a sealed bag in your dustbin.
- If your cat normally uses a litter tray, remove the faeces (droppings) every day and disinfect the tray every week using hot water.
- Check your cat for signs of fleas and treat them regularly using the product recommended by your vet. Fleas are more numerous during summer and autumn, although they will survive all year round in centrally heated homes.
- Discourage your cat from hunting rodents by keeping it indoors at night.
- Children will put dirty fingers and other objects into their mouths and this may bring them into contact with worm eggs. Make sure that they wash their hands after playing in a garden or other open areas which may have been used as a toilet by cats. Remember the greatest risk of children being infected with worms is from other children not your cat.