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How Do Dogs Get Intestinal Worms?

While most dog owners understandably don’t want to think too hard about parasites, the truth is that intestinal worms are a common problem for our canine companions.

Worms can cause a range of unpleasant symptoms, from diarrhea to weight loss. And if untreated, they can even become life-threatening in some cases.

Where do dogs get worms from though? And how can they be prevented? Keep reading to find out.

Which Types of Intestinal Worms Are Most Common in Dogs?

There are a range of intestinal worms that can affect dogs. The most common are:

  • Hookworm. These short worms take up a lot of the dog’s nutrients. This makes them a dangerous type of parasite, particularly for puppies.
  • Roundworm. Two roundworm species can affect dogs, but both have a long, white appearance. Roundworm infections typically start in the intestines, but can move through the body, including into the lungs.
  • Tapeworm. Tapeworms are longer than other worms that affect dogs and can grow to more than half a foot. When the worm matures, small segments may appear in the dog’s faeces or around the anus (often compared to rice grains). The segments are full of worm eggs.
  • Whipworm. These worms reside in the dog’s large intestine. They are typically less dangerous than hookworm, as they don’t take up the same quantity of nutrients. The exception is if the worm starts to burrow into the dog’s intestinal tissue.
Types of worms and sizes

How Do Dogs Get Intestinal Worms?

Most worm infestations begin when the dog swallows worm eggs. This can occur directly from eating the faeces of an infected animal, but also by licking eggs that have become stuck to their fur. Let’s take a closer look at the most common sources of worms in dogs.

From Fleas

Many dog owners may be surprised to learn about the connection between fleas and tapeworms. Fleas often carry tapeworm larvae, so there is a risk that your dog licks one from their fur when grooming – particularly as dogs often bite and lick itchy areas.

Once inside the dog, the tapeworm larvae mature inside the intestine. It’s a cycle that highlights the importance of regular flea prevention.

From Eating Substances Containing Worm Eggs

Dogs risk contracting roundworms, whipworms, or hookworms by eating a substance containing eggs or larvae.

The faeces of other dogs or animals (including rabbits and foxes) are probably the most common culprit, but soil or even grass can harbour worm eggs. Live prey animals, including mice and birds, may also contain tapeworms or other parasites.

It’s very difficult to stop dogs from eating random (and often disgusting) things on walks. But you can minimise the risk at home by regularly removing any animal faeces from your garden.

Additionally, dogs who are fed raw food diets are at greater risk of parasites. Without cooking, there is no heat to kill parasites (and bacteria) that might be in the food.

From Self-Grooming

Eggs that are caught in the fur of your dog can easily be licked off when they are grooming.

For example, if your dog has been rolling in soil or faeces when on a walk, they may consume eggs when they later groom dirt from their fur. This is particularly common with roundworm eggs, but can happen with other types of intestinal parasites too.

Note: Some worm eggs can stay active for years in the soil. So, just because there isn’t any visible faeces doesn’t mean the soil is parasite-free.

From Walking on Soil Containing Hookworms

Hookworm has been known to burrow through a dog’s skin via the paw pads. So, just walking over the larvae can put the dog at risk of an infection.

From Their Mother’s Milk or Placenta

If a mother dog is infected with roundworm, then the infection can be passed to the puppy via her milk. The result is that suckling puppies are at a real risk of getting a roundworm infection, which is why worming prevention is essential for puppies.

“I strongly advise breeders to start worming pups from as young as 2 weeks old with a broad-acting wormer such as Fenbendazole,” says vet Dr Linda Simon. “They should then be regularly de-wormed every few weeks.”

Additionally, an infected mother can pass parasites to her unborn puppies through the placenta. The consequences for young puppies can be tragic; roundworm infections can escalate to severe levels, sometimes with fatal outcomes.

Symptoms of Intestinal Worms in Dogs

An unwell dog with parasites

Symptoms of worms in dogs are often subtle and difficult to spot. That’s why a consistent worm prevention plan, with the advice of your veterinarian, is crucial.

There’s a chance you might spot worms in your dog’s faeces or even in their vomit. Occasionally, the worms might be visible near the pet’s rear end.

But worms are more likely to cause less obvious symptoms, such as:

  • Unexplained weight loss
  • Coarse and dry fur
  • A coat that loses its natural shine
  • Increased hunger to make up for nutrients lost to the worms
  • Diarrhea
  • Vomiting
  • Cough
  • General weakness or lethargy
  • Other symptoms caused by nutrient deficiencies
  • Distended “pot bellied” appearance in puppies (usually an indication of a severe infection)

If you notice any of these symptoms, or other symptoms of illness, it’s important to contact a vet. The right treatment depends on the type of worm, so it’s important to get an accurate diagnosis.

Bringing a sample of the worms to your vet can also be helpful. Make sure you don’t touch the worms, but wrap them in damp cotton wool.

How to Prevent Worms in Dogs

As with all medical issues, it’s always much better to prevent a parasitic infection than to wait until your dog needs treatment.

The best way to prevent worms is with regular worm treatment. You should discuss the various options with your vet to find the right dewormer for your pet.

Aside from a worm treatment, there are several other ways you can reduce the chance of your dog’s catching intestinal worms:

  • Regularly clean your dog’s water and food bowls
  • Keep your garden clear of any animal faeces, particularly from foxes, cats, and your dog
  • Watch out for animal faeces on walks and try to prevent your dog eating it

Frequently Asked Questions

Can Humans Catch Worms From Dogs?

While rare, humans are not immune to contracting parasites like roundworms and whipworms from dogs. There have also been reported cases of humans catching tapeworms after accidentally eating a flea that’s carrying larvae, although this is thought to be very rare.

“It’s important we practice good hygiene, always washing our hands well with soapy water after disposing of our dogs’ faeces,” says vet Dr Linda Simon. “I always tell parents of little ones to have them wash their hands after they touch their dog, as their hands inevitably go in their mouth shortly after!”

How Long Do Worm Eggs Survive When Not in a Host?

Many people are surprised to learn that worm eggs can live from several months (roundworms) to up to 5 years in the soil. So, while the worms come from an animal’s faeces, they can remain in soil and grass long after any traces of the faeces have disappeared.


Intestinal worms are a serious issue for dogs that shouldn’t be ignored. Dogs can pick up these parasites in a range of different ways, including by licking eggs from their fur, eating faeces containing worm eggs, and even via their mother’s milk.

The good news is that most serious worm infections can be prevented with a regular worming treatment. You should discuss this with your vet to ensure your dog gets the dewormer they need.

Do you have any questions about how dogs get worms? Please let us know in the comments section below.


Richard Cross

Richard is a journalist who specialises in dog behavior. He's written hundreds of articles and books related to dogs, including for the Continental Kennel Club, Dog Fest (the UK's biggest dog festival) and various veterinary surgeries. When he's not spending time with Jess and Rudy (his beloved Labrador and Golden Retrievers), he enjoys reading, hiking and watching sports.
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