The internal parasites (endoparasites) that commonly affect cats and dogs in the UK are roundworm, tapeworm and lungworm.

Roundworm

Puppies can be heavily infected by roundworm before birth or via lactation, which can lead to serious illness. Therefore puppies are normally treated with a de-wormer (known as an anthelmintic) at two weeks of age, and this is repeated until they are six months old.

Kittens are not infected before birth and so are usually wormed from three weeks of age until they are six months.

Roundworm infection can occur in older dogs and cats, but is not usually associated with obvious signs, so it is difficult to know if they are infected without regular examination of the faeces.

It is usually recommended to continue regular €“ at least four times a year €“ de-worming in adult cats and dogs. More frequent worming (monthly) is recommended for animals that live in households in which there are people who might be particularly susceptible to disease if infected, such as young children or people with immunosuppression.

Tapeworm

Dogs are at risk of infection with tapeworm if they have a raw meat diet, hunt, or otherwise have access to raw offal and carcasses. Other tapeworms that infect dogs are spread by fleas and biting lice.

Lungworm

Lungworm infects the lungs and heart in dogs and can cause serious disease. Dogs can acquire the infection through ingestion of slugs, snails, frogs and other amphibians. Drugs for treating and preventing lungworm are only available on veterinary prescription.