Dog Worms: How Do Dogs Get Roundworms?

Got worms? Nearly all puppies are born with or contract roundworms. Learn how to prevent and treat this pesky parasite.

What are roundworms?

Roundworms are a common parasite that lives in the intestine of young dogs and puppies. If you have heard about a dog having “worms,” roundworms are the most likely culprit. While easily prevented and treated, an infection of roundworms can lead to weight loss, diarrhea, failure to thrive, and a pot-belly appearance.

How do dogs get worms?

  • Almost every puppy is born with, or acquires, roundworms.
  • Roundworms are most commonly spread through feces. As puppies tend to be less fastidious in their hygiene they are more likely to be exposed to worms.
  • Roundworms can be passed to puppies through the mother before birth or through her milk.
  • Puppy immune systems are immature and unable to fight the infection.
  • Dogs gain resistance to these worms as they age.
  • Roundworm eggs survive in the soil for a long time, sometimes several years. All feces in the yard should be promptly cleaned up to avoid eggs.

Are roundworms contagious to humans?

While adults with fully devleoped immune systems aren’t typically at rish, infant children can get infected with roundworms if they ingest dirt containing roundworm eggs. Parks where dogs are allowed to run are also risky areas for toddlers who are inclined to eat dirt.

Preventing worms in dogs

Roundworms are easily prevented by a series of de-worming medications every two weeks starting from when a puppy is born. This medication is usually given in liquid form, so it is easy for dog owners to give.

Keeping a clean environment can also reduce the risk for worms. Pick up poop in the yard as quickly as possible and keep your dog away from other dog’s feces.


If your puppy has not been treated for roundworms as a part of prevention, and has diarrhea, most likely there is an infection. Your veterinarian will want to look at a stool sample under a microscope, where the diagnosis can be confirmed by the presence of roundworm eggs.

Once your puppy is old enough to go on heartworm medication, the roundworms will be controlled also, so further treatment or prevention is not necessary. For this reason, it is recommended that your dog stay on monthly heartworm prevention year-round.

Talk to your veterinarian about getting your dog on an effective de-worming program that prevents heartworms, roundworms and hookworms.


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