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Intestinal Worms in Dogs

What are intestinal worms?

There are four types of intestinal worms.  All pose a serious health risk to your dog if they go untreated, with roundworm being the most serious.  Other types of intestinal worms found in the UK are hookworms, whipworms and tapeworms. Dogs can become infected by their mother, contaminated soil or consuming contaminated meat.


Roundworms (Toxocara canis and Toxascaris leonine)

There are two types of roundworm; toxocara canis and toxascaris leonine.  These long, spaghetti like parasites live inside and feed off the intestines. The toxocara canis larvae can, however, burrow its way into the lungs to develop then travel up the airways where it will be coughed up and swallowed again, returning to the intestine and completing its life cycle.

What are the symptoms of roundworms?

Not all dogs show symptoms, so the first time you become aware of your dog being infected with roundworms will be when you notice them in his faeces or vomit.  Symptoms your dog may show are: –

  • Weight loss
  • Bloated stomach
  • Diarrhoea
  • Vomiting
  • Dull coat

If you pet is showing any of these symptom, take him to your vet.

How do dogs get roundworms?

Puppies are at most risk as they can become infected from their mother from before birth or by drinking her milk.  All dogs are at risk if they eat the roundworm eggs which may be found in another animals feaces, contaminated soil or by eating small infected animals such as mice.  Once consumed the eggs can hatch and begin their life cycle.


Hookworms (Ancylostoma and Uncinaria)

These blood sucking parasites are 5-16 mm in length. They are a particular danger to puppies and can cause death. Their life cycle is similar to the toxocara canis roundworm in that it moves into the lungs to mature, then re-enters the small intestine.

What are the symptoms of hookworms?

Due to the leaching nature of this parasite, drawing nutrients from its host, your pet will appear lethargic and depressed and generally not himself.  Symptoms to look out for are: –

  • Poor appetite
  • Anaemia
  • Persistent cough
  • Tar-like stools (consistency and colour)
  • Dull coat
  • Diarrhoea or constipation
  • Weight loss

How do dogs get hookworms?

Similar to roundworm, pets can become infected by ingesting the larvae, either as puppies from their mother’s milk or from another animal’s faeces, contaminated soil or by eating small infected animals such as mice.  A large number of foxes are understood to be infected with hookworm, which brings an added risk to dogs where foxes are common.  Hookworm larvae can also penetrate the skin so merely walking across contaminated ground poses a risk of infection.


Whipworms (Trichuris vulpis)

These intestinal worms live in the large intestine. A mild infection will not deprive its host of as many nutrients as other types of worms so rarely cause problems or any symptoms. However, the infected animal can still spread the parasite. As the infection increases, symptoms are likely to become more apparent.

What are the symptoms of whipworms?

As the infection increases your pet may start to show the following signs: –

  • Bloody diarrhoea
  • Dehydration
  • Anaemia
  • Weight loss
  • Licking stomach
  • Lethargy

How do dogs get whipworms?

Like other intestinal worms, dogs contract whipworms by ingesting contaminated food, water or soil. Infection can also occur by your dog simply licking his paws, as whipworm eggs can live in the environment from just a few months to year due to their resistance to both high temperatures and freezing.



Tapeworms live in the small intestines, latching onto the intestine wall and absorbing nutrients as food is digested. A tapeworm can easily be from 6 inches to 28 inches in length. It has a segmented body with, as the name suggests, a flat appearance.

What are the symptoms of tapeworms?

The tape worm is made up of small segments, and when excreted can look like grains of rice.  These segments can be seen in the dog’s faeces or around the anus. Physical symptoms your dog may exhibit are: –

  • Diarrhoea
  • Lethargy
  • Scooting (dragging bottom on the floor)
  • Weight loss with increased appetite
  • Excessive licking of anus

How do dogs get tapeworms?

As with other types or worms, a dog can become infected by consuming contaminated food, soil, faeces and water, however, the most common way of contracting tapeworms is by ingesting fleas or flea eggs through grooming.


Diagnosis of intestinal worms

Other than in the case of tapeworms (see above), it is difficult to tell if your dog has intestinal worms.  Your pet can have worms without showing any obvious signs of illness. Usually only minor signs can be seen.  This can result in your dog shedding the worm eggs in their faeces, infecting other animals.  If you do suspect your dog has worms take him along to your vet.  The vet will want to hear about any symptoms of ill health your pet has been showing and will give a thorough examination. To confirm diagnosis the vet is likely to want to examine a faecal sample under a microscope by conducting a faecal flotation test and/or take a blood test.


What treatment is available for intestinal worms?

To avoid your dog getting worms in the first place, it is important to give them regular worming treatment.  Puppies are particularly at risk.  There are many types of treatment so it is essential to get the best advice on worming and how often, from your vet. Treatments can be administered by injection, tablet or spot treatments. Puppies need to receive a worming treatment every 2 weeks between the ages of 2 to 12 weeks, sometimes longer. Adult dogs should routinely receive worming treatment at least 4 times a year, or more often if you have young children in the household.  A female who is pregnant or is feeding pups will also need worming and have her treatments kept up to date.  Ask your vet about frequency and the best treatments to use.

If your dog already has worms, it is unlikely one single treatment will completely get rid of the infection so repeated treatments will be necessary.


How to prevent intestinal worms

It is important your dog receives regular worming treatments, as advised by your vet.  This will protect him if he comes into contact with contaminated areas, items or other animals.  Treatments for intestinal worms can be brought from different outlets, but not all treatments will protect your pet against all types of intestinal worm.  Initially seek advice from your vet about the most appropriate treatment for your pet to ensure they are fully protected.

Ensure you pick up any faeces left by your dog, whether this is in your garden or out and about.  Worm eggs can survive for a long time in the environment so removing faeces left by your pet is very important, especially in areas where children might play.  Hookworms, whipworms and roundworms can be passed on to humans, with roundworms being most commonly transmitted. Children are at particular risk in areas where dogs are allowed to defecate. Always apply strict hygiene routines (e.g. hand washing before meals) around parks and gardens to reduce the risk of infection.

Cats are also at risk from being infected by round worms (toxascaris leonine only), hookworms, tapeworms and whipworms.  It is, therefore, essential that cats, particularly in households shared with children and other pets, receive regular worming treatments.