Are worms really a risk in pets?

There are lots of different worms that our pets can pick up. Infection is common and many pets do not show signs. Furthermore some worms can cause harm to people.

In this blog we will look at the types of worms that affect our pets, how they get them, and how they pose a threat to our pets and us.


These are the most common worms, and most problematic for us and our pets.

What do they look like?

Although there are many different roundworms, they all appear spaghetti-like. In the UK the main species in dogs is Toxocara canis, and in cats Toxocara cati.

How does my pet get them?

Infection is very common in puppies and kittens. The immature larval stages of these worms lay dormant in pets and, awakened by pregnancy and feeding, are spread to the puppies or kittens from their mother. For this reason, always assume your puppy or kitten will have some roundworms! Eggs passed by infected dogs, cats and foxes infect the environment and are a source of infection for adult pets.

What signs do they cause?

They can cause vomiting or diarrhoea, a pot-bellied appearance, coughing, weight loss, general ill thrift and possibly death (through gastrointestinal obstruction, for example). You are unable to see the eggs.

Can humans get roundworms?

Although adult roundworms cannot live in people, Toxocara eggs that are eaten can pose a risk to humans, especially young children or immunosuppressed individuals. As larvae migrate through the body they can lead to blindness, as well as many other damaging clinical signs. It is important to note that fresh poo is not a risk as it takes several weeks for the eggs to become infectious. Don’t panic about touching your pet either – although it is generally good hygiene to wash your hands after touching them, the environment is more a risk than the pet itself.

Cleaning up faeces immediately and always wearing gloves when handling poo or gardening is important. Contaminated soil and sand pits are the main threat to children and gardeners, and studies have shown up to 67% of public parks sampled, and 75% of sandpits, were contaminated with roundworms and their eggs.


What do they look like?

Tapeworms are generally long, flat worms composed of many segments. Mature segments containing eggs are released from the end of the tapeworm and are passed in faeces. These segments often resemble grains of rice and can sometimes be seen on the hair around the bottom of your pet.

How does my pet get them?

Tapeworms require an intermediate host to first eat the eggs from the environment, and then the pet will become infected by eating the intermediate host. Animals that act as intermediate hosts vary depending on the species of tapeworm. The most common worldwide are called Dipylidium caninum, and Taenia taeniaeformis.

Dipylidium caninum is the most common tapeworm in the UK and is transmitted by fleas. The fleas eat the eggs of the worm and infection is then passed on to the pet when it swallows an infected flea during grooming. It should be assumed that any pet infected with fleas also has Dipylidium caninum (and vice versa).

The Taenia– family of tapeworms are usually passed on when the pet eat small rodents (rats and mice), the rodents having eaten eggs from the environment. This infection occurs very commonly in cats that hunt. Dogs may be infected by eating carcases or raw meat.

Neither species commonly cause clinical signs, although can cause an itchy bottom, diarrhoea, poor coat quality and a desire to eat more. Occasionally, though, a heavy burden may cause the gut to turn inside itself, called an intussusception, especially in younger animals; this requires emergency surgery to repair.

Can humans be infected?

Echinococcus granulosus can infect dogs (it occurs in the UK, but is thought to be more common in select areas such as South Wales) and the closely-related E. multilocularis can infect dogs and cats (but does not occur naturally in the UK). These tapeworms can use humans as intermediate hosts, causing potentially serious cysts in people.

Dogs should be prevented from eating infected carcases, and not be fed raw meat that could be potentially infected. Obviously wearing gloves and washing carefully if handling poo or soil is vital. The pet travel scheme means dogs need to have a tapeworm treatment before entering the UK to prevent introduction of these more dangerous parasites. With greater movement of pets there is a greater threat of new species of parasites entering the UK.

Other intestinal parasites such as Hookworms and Whipworms are less common in the UK but may need further discussion if your pet is going to travel.


Lungworm, the only non intestinal worm on our list, can be life threatening and its prevalence seems to be on the rise. It cannot be transmitted dog-to-dog, but requires a dog to eat its intermediate host: snails or slugs. There is evidence of infection through contact with slime from these creatures also. It can affect dogs of all ages and breeds as well as foxes, but younger dogs, because of their playful nature, are more at risk. Coughing, breathing issues, not wanting to exercise and bleeding issues are the most common signs. It can be fatal but is also preventable.

With so many worms, and options, which ones do I worry about?

Our pets are all individuals with differing lifestyles that will affect their risks of contracting worms. If your dog or cat rarely ventures outside, their risk of parasite infection is lower than that of a farm dog. This may affect the frequency of treatment needed. Tapeworms are less common in young pets unless they have fleas, and cause most issues in hunting cats. Roundworms are much more common in young pets, which is why they need worming more frequently. Lungworm is only a major concern if your dogs eats snails/slugs or anything in contact with snails or slugs. If your pet travels they will also be more at risk of foreign worms.

How do I minimise the risk?

Firstly, reducing the load of infection in the environment is important. We must all be responsible dog owners by disposing of fresh poo. The older the poo, the more the risk of spreading parasites. The same goes for cats with litter trays. If your cat goes outside this can be difficult.

Secondly a tailor made worming routine is vital. One of our vets can assess your pet’s lifestyle and risks, tailoring a regime to your individual pet. There is a plethora of effective worming treatments on the market, treating different species of animal, different sizes of pet, and different worms.There are also many ineffective products in pet shops, supermarkets and on the internet. Some of these may even be harmful to your pet. A member of our trained veterinary team can point you in the right direction.

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