It can be alarming to discover that your pet 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.

Types of Worms Affecting Dogs and Cats

There are two important types of parasitic worm in dogs and cats - 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 animal's intestines along with two other types of smaller worm (similar to roundworms) called whipworms and hookworms. However, these rarely affect dogs and cats in the UK. In some countries there are parasitic worms that can live in the lungs, heart, stomach or bladder but these are rarely seen in Europe.

Damage caused by worms

Intestinal worms help themselves to your pet's food and can damage the gut causing loss of blood. Worms can also cause diarrhoea, dehydration and anaemia, and this may make your pet run-down and susceptible to other diseases. If there are a lot of worms your pet may cough, lose weight, have a rough, dry coat or a 'pot-bellied' appearance. In puppies and 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 animal) and this may be fatal.

How worms are passed on

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 dog or cat) or indirectly, (after being swallowed by a rodent which is then eaten by the dog/cat). Immature worms also survive in the tissues of an infected animal. If the pet is female and has puppies/kittens they make their way to the animals' breast and are passed to the offspring 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 of the pet's bottom. They may wriggle like a maggot for a short time and then dry up (sometimes still attached to the fur). The most common type of tapeworm moves on to a new animal by way of fleas. Immature fleas live in the environment and eat a variety of solid food including faeces (droppings). The next dog/cat will become infected when it swallows an adult flea whilst grooming itself. There is also a less common type of tapeworm which uses mice, other rodents and rabbits to complete its life cycle. The parasite forms inactive cysts in muscle or other organs of the host and your pet is then infected if it eats a small rodent or rabbit.

How to tell if your pet has Worms

Apart from the general effects on health described above, signs of infestation are to be found in your pet's faeces (droppings). Young animals may vomit or pass roundworms (looking like string) in their faeces. Segments of tapeworm (looking like grains of rice), can often be seen in the droppings or in the fur around its bottom. You may be startled to see them move. Roundworm eggs can only be seen by using a microscope.

How to get rid of Worms

There are some highly effective treatments which will kill worms. These are available as liquids, 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 pet. Worms are so common that it is safe to assume that any pet with fleas, or animal which regularly catches wildlife will be infected. Puppies/kittens should be dosed every two weeks, from four weeks to 16 weeks of age, and older pets should be treated about every three months. You should discuss with your vet the most appropriate treatment regime for your pet.

Worms are a zoonosis

The common roundworm found in dogs is a rare but potentially serious cause of human disease. The larval stages 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.

Reducing the Risk

Apart from regularly worming your pets, there are a number of other measures which can stop worms being passed on from pet to pet, or from pet to people.

·       If your pet uses your garden as a toilet, clean up the faeces (droppings) and bury them or put them inside a sealed bag in your dustbin.

·       Check your pets for signs of fleas and treat them regularly using the product recommended by your vet. Fleas are more numerous during summer and autumn.

·       Keep cat litter trays clean and disinfect them weekly with hot water.

·       Discourage your cat from hunting by keeping it in 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 be used as a toilet by dogs. Remember the greatest risk of children being infected with worms is from other children, not your dog.