Worms and Worming in Cats and Dogs | Veterinary Prescriber
Worms and Worming in Cats & Dogs: What You Need to Know
There are many responsibilities that come with having a pet cat or dog. Among these is ensuring the pet stays healthy, including remaining free from parasite diseases. Cats and dogs can be affected by external parasites (ectoparasites), such as fleas and ticks. They can also be affected by internal parasites (endoparasites). In the UK, the most common internal parasites that affect cats and dogs are types of parasitic worm. This is why cats and dogs need worming from time to time. In this article we describe the main types of worm that affect cats and dogs in the UK together with worming recommendations.
Roundworm
Roundworm (Toxocara) is the most common internal parasite affecting cats and dogs in the UK. Roundworm does not normally cause disease in pets unless the worms are present in large numbers in the intestines. Kittens and puppies are most likely to become ill through roundworm infection because roundworm is transmitted from the bitch to her puppies via the placenta or in her milk; it is transmitted from the mother cat to her kittens only in her milk. Worming kittens and puppies is very important because it stops them becoming unwell as a result of roundworm infection.
In older cats and dogs, regular worming is needed mainly to stop roundworm from being deposited in faeces and to prevent it being transmitted to humans.
Why adult cats and dogs need worming for roundworm
After kittens and puppies are infected with roundworm, the roundworm usually remains dormant (inactive) in the animal’s body, but it can reactivate from time to time. Although this does not usually cause problems to the cat or dog, it does mean that the roundworm eggs can be deposited in the cat’s or dog’s poo. Cats and dogs can also pick up new roundworm infection if they eat infected prey (such as birds or rodents).
Any eggs deposited in fresh cat or dog poo are not a problem because the roundworm eggs in fresh poo are not infectious. It takes several weeks after they are deposited for roundworm eggs to mature and have the ability to infect people. This is one of the reasons why it is important to pick up dog poo and dispose of it carefully. Unfortunately it is not so easy to control cat poo in the environment, unless the cat uses a litter tray (or fox poo – foxes also carry roundworm).
Roundworm can be transmitted to people when a person ingests infective (mature) roundworm eggs in contaminated soil or sand, or from unwashed hands or vegetables or toys that have been in the garden. This is a reminder why hand hygiene and washing fresh fruit and vegetables before eating is important! Thankfully, the chance of a person becoming ill from roundworm infection is very small.
How often do adult cats and dogs need worming for roundworm?
Vets recommend worming cats and dogs at least 4 times a year (every 3 months). But for some pets, the recommendation is for more frequent worming.
Young children aged 2 to 4 years and people with a condition or on medication that suppresses the immune system may be at higher risk of picking up roundworm infection. If the cat or dog has regular contact with these people monthly worming for roundworm is recommended.
If the pet catches/eats prey (such as birds or rodents) monthly worming for roundworm is recommended.
To read more about parasitic worms in cats and dogs and about veterinary worming recommendations, see ESCCAP UK&Ireland’s guidelines.
Tapeworm
There are two main types of tapeworm that can affect cats and dogs in the UK:
Taenia tapeworm. Cats and dogs can become infected by eating infected prey (such as mice or rabbits) or through eating unprocessed raw meat or offal. Cats and dogs are usually unaffected, even by large numbers of worms and the worm poses no danger to people. But owners may not like the sight of worm segments in faeces or crawling around the pet’s anus.
Dipylidium tapeworm. This is carried by fleas and lice so infection in cats and dogs occurs either through grooming or by eating infected prey. Cats and dogs are usually unaffected, but the worms can be transmitted to humans if fleas are accidentally ingested, and adult worms may develop in the human intestine, although this is rare and does not usually cause problems. Control of this parasite in cats and dogs mainly depends on flea control.
How often do cats and dogs need worming for tapeworms?
Cats and dogs that eat prey or that are fed raw unprocessed meat or offal are at risk from being infected with tapeworm. Worming every 3 months with a tapewormer is recommended for most dogs that are at risk of tapeworm infection.
For pets that are imported or travel abroad and return to this country there are strict rules about worming, to prevent importation of a tapeworm called Echinococcus that can be transmitted to humans and cause serious disease. For imported cats or dogs or travelling pets, read the government’s information about tapeworm control.
To read more about parasitic worms in cats and dogs and about veterinary worming recommendations, see ESCCAP UK&Ireland’s guidelines
Lungworm (Angiostrongylus Vasorum)
The lungworm Angiostrongylus vasorum (pronounced anjio-strong-gill-us vase-or- um) is a parasitic worm that can infect dogs and live in the heart and in the blood vessels in the lungs. Dogs infected with this lungworm can become severely ill and even die.
A. vasorum is carried by slugs and snails. Dogs can become infected when they eat slugs and snails infected with the parasite. Dogs are at risk of infection if they eat slugs or snails, either deliberately or accidentally, perhaps through eating grass. It is not known if dogs can become infected through contact with slug or snail faeces or slime trails. It is not possible to know if the slugs and snails where your dog lives and walks are infected with the parasite. Reports of cases of lungworm in dogs can suggest that it is present in the area. However the absence of reported cases in an area cannot be taken as proof that there is no lungworm in that area.
It is possible to prevent lungworm disease developing in dogs with regular worming treatment. A vet can advise on whether a dog needs regular worming to prevent lungworm disease and can prescribe a preventive wormer if needed.
To read more about parasitic worms in cats and dogs and about veterinary worming recommendations, see ESCCAP UK&Ireland’s guidelines.
Worming Products for Cats & Dogs?
Most cats and dogs need regular worming for roundworm and some also need worming for tapeworm. Different worming drugs are needed for roundworm and tapeworm. The two types of drug are sometimes available in combination products. Wormers for roundworm and tapeworm can be bought over-the-counter without a veterinary prescription, or can be prescribed by your vet. If buying over-the-counter, get advice from an SQP (a regulated animal medicines advisor employed in many pet stores).
Wormers to control lungworm in dogs cannot be bought without a veterinary prescription. Talk to your vet about lungworm to find out if your dog is at risk and needs preventive worming for this parasite.
There is a vast array of worming products on the market!
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