In dogs the most common roundworm is called Toxocara Canis, pictured here. Cats are most commonly infected by Toxocara Cati.

A third roundworm species Toxascaris Leonina can occur in both dogs and cats but is far more frequent in cats.

How can my pet get roundworms?

Dogs and cats can be infected with worms at any stage of their life, even when very young. Infection occurs in three ways:

  • Puppies or kittens of an infected mother are infected via the placenta and while sucking.
  • Eggs are passed out in the feaces and can be ingested from the soil or while grooming
  • Rodents, eg mice or rats, caught by cats or dogs are a common source of worms

How do worms affect my pet?

In young puppies and kittens roundworm infections can cause diarrhoea and vomiting and result in the puppy or kitten becoming thin and taking on a typical “pot-bellied” appearance. Worms may be vomited up and young animals can become aneamic or develop pneumonia. If there are large numbers of worms they can cause bowel obstuction in kittens and puppies.

Older animals are less likely to have life threatening symptoms, but worms can be a cause of poor condition and weight loss.

How will I know if my pet has worms?

Roundworms are white and quite like long thin earthworms in appearance. It is not uncommon for an infected pet to pass roundworms in their stool or to vomit them up.

Almost all puppies and kittens are infected with worms and should be treated regularly between 2 and 12 weeks old. In older animals you may not see any outward signs until there is a very heavy infestation, however regular worming is the best way to ensure that this never occurs.

How can I prevent my pet getting roundworm?

Treatment differs depending on the age of your pet:

  • Newborn pups and kittens should be treated first at 2 weeks of age and then every two weeks until they are 12 weeks old.
  • Adult cats and dogs should be treated approximately every 3 months, though the exact frequency will depend on the product used.

There are two reasons why treatment, even in adults, needs to be frequent:

  • Reinfection occurs easily, with worms eggs readily ingested from the environment.
  • When a dog or cat ingests worm eggs, they do not simply develop into adult worms in the gut. Instead they hatch and the larvae burrow through the wall of the gut and into the blood stream.
  • From there they go to various tissues thoughout the body and form cysts, which can remain dormant for weeks, months or even years before eventually making their way back to the gut and becoming adult worms.
  • No worm medication currently available can kill the larvae or the cysts.

Are roundworms a risk to human health?

Toxocara Canis, the dog roundworm, can cause “Visceral Larva Migrans”, a serious condition which occurs mostly in children. It occurs when worm eggs are ingested, quite often from the soil.

While the eggs cannot develop into an adult worm in a human, the larval stage can hatch from the egg and burrowing larvae can develop into tiny cysts in various parts of the body. They do not survive long and in most cases cause no harm but if they lodge in the eye they can cause serious inflammation which can lead to blindness.

As well as regular worming for all pets, teaching children to wash their hands after playing outside is important in preventing infection.