A woman pets her happy dog
A woman pets her happy dog

Hookworms and Roundworms: The Invisible Threats

Roundworms and hookworms are dangerous—and often invisible—threats to your dog. They live in the intestines after being ingested by a dog and can cause many complications in the gastrointestinal tract. With HEARTGARD Plus chews, you can help treat and control hookworms and roundworms in your dog.

What Are the Most Common Intestinal Parasites in Dogs? 

Two of the most common types of intestinal parasites in dogs are hookworms and roundworms. 

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Image of a hookworm up close


Hookworms are intestinal parasites that can live in your dog’s digestive system. True to their name, they attach themselves to the intestinal wall by literally hooking onto the tissue. Hookworms feed on a dog’s blood and eject their eggs into the digestive tract, which allows them to be passed into your dog’s environment via their feces.1

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Image of a roundworm up close


Roundworms, also known as ascarids, are the most common parasitic worms found in dogs. This parasite spreads easily, which means infection is very difficult to control. Adult roundworms live in the dog’s intestines and feed off partially digested food.2

How Do Dogs Get Hookworms and Roundworms?

There are multiple ways your dog may contract hookworms or roundworms, most of which involve dogs ingesting parasites either directly or indirectly. The threats are everywhere if you know where to look.

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A small mouse

How Dogs Get Hookworms

Hookworm larvae can be transmitted through the skin or by ingesting larvae in contaminated soil or grass in your dog’s environment. Dogs may also contract hookworms by eating other infected animals—usually rodents. Puppies can also be infected if they ingest hookworm larvae while nursing.1

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A dog in the backyard

How Dogs Get Roundworms

Roundworms are extremely common in young dogs, infecting over 90% of puppies. It’s very common for mothers to pass roundworms to their puppies prior to birth or even while the puppies are nursing. Both puppies and adult dogs may also contract roundworms by ingesting roundworm eggs from their environment, while grooming, or by eating infected animals.2

Signs of Intestinal Worms in Dogs

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Prompt treatment of dogs can help reduce further damage as well as mitigate the possibility of the worms spreading. Pet owners should be aware of the warning signs that can indicate if their dog may have intestinal worms.


Common signs of hookworm and roundworm include:2,3 

  • Diarrhea 
  • Vomiting
  • Weight loss
  • Poor coat appearance
  • Swollen belly
  • Lethargy
  • Dehydration
  • Anemia
  • Intestinal blockage
  • Pneumonia
  • Blood in stool
A tired looking dog laying on its bed A tired looking dog laying on its bed

How to Diagnose Intestinal Parasites in Dogs

The only way to confirm a hookworm or roundworm infection is with a test called fecal flotation, which your vet will perform.1,2 This is a test performed on your dog’s stool sample that allows your vet to detect the presence of internal parasite eggs.

How to Treat Hookworm and Roundworm

The best way to address the presence of hookworms or roundworms in your dog’s system is to have a conversation with your vet. A licensed veterinarian will recommend the best course of action for your dog, which may include deworming medication or a medication and changes in management practices (sanitation).


Your vet can also prescribe a monthly parasite treatment, like HEARTGARD® Plus (ivermectin/pyrantel).  Regular treatment and control, along with sanitation, is the best course of action when it comes to hookworm and roundworm infections. 

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A woman and her dog, who has a small bow on, listen to the vet speak

Intestinal Parasite Prevention

There are many things you can do to reduce the risk of hookworm and roundworm infection in your dog. Best practices include cleaning up your dog’s poop regularly, limiting your dog’s access to areas where other dogs frequently use the bathroom, and talking to your vet about starting a monthly intestinal parasite treatment.

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A woman gives her dog a Heartgard Plus chew

HEARTGARD Plus Chews Are Effective Against Hookworms and Roundworms

HEARTGARD Plus chews treat and control 3 species of hookworms and 2 species of roundworms.* Hookworms and roundworms pose a serious threat to dogs. Left untreated, they can cause blood loss, weight loss, and/or diarrhea. While uncommon, in more serious cases, they can even cause death. That’s a chance you don’t want to take. Treat and control these threats with HEARTGARD Plus chews.

Need a prescription? Find a vet near you using our Find A Vet tool.

Fleas and ticks are threats to your dog, too. Pair up HEARTGARD Plus Chews with powerful flea and tick protection.