Roundworms in Dogs


"Roundworms in dogs have several varieties. Symptoms vary based on the type of worm and treatment options are highly effective."


Dog Roundworms (also called nematodes) are 3 to 5 inches long and live in your dog's intestines. These worms do not attach themselves to the intestine, and produce eggs which can be found with a microscope in the dogs feces. There are many types of worms in the roundworm family:

  • Esophageal Worms
  • Stomach Worms
  • Small Intestine Worms (hookworms, thread worms)
  • Colong (whipworms)
  • Heart and Lungs (heartworms, lungworms)
  • Urinary Tract/Kidneys (dictophymae, capilaria)
  • Eye

Roundworms In Canine Puppies

All puppies that have roundworms probably inherited from their mothers in the womb or when nursing. It is possible that the mother tested negative for roundworm, yet still passed it on to their puppies. This happens because worm eggs can hide in muscle tissue and not be detected. Puppies can also get the disease from mothers milk.

Puppies with roundworms can show no symptoms or have soft stools. It is not uncommon to see 2 to 4 inch worms in diarrhea or vomit.

Warning signs requiring immediate treatment by a Veterinarian include if your puppy is acting weak or is having one or more bouts of diarrhea or vomit a day.

Puppies are usually given a dewormer before they leave the breeder and within the first 3 weeks under the care of a Veterinarian.

Symptoms of Roundworms in Dogs

In adults, roundworms are usually not harmful, but can cause a loss in weight, weight gain in the belly which looks like a pot belly, or weakness in your dog. When symptoms are present they can depend on the type and area affected, and include:

Esophageal Worms - Usually do not cause symptoms. If there are symptoms, they include excessive saliva from the mouth, difficulty swallowing and vomiting.

Stomach Worms - Excessive gas, vomiting and dark feces

Small Intestine (hood, thread) - vomit or diarrhea (can usually see the worms)

Heart and Lungs - Coughing, weight loss, weakness

Lung Worms - Coughing, breathing problems

Urinary Tract - Frequent Urination, Difficulty urinating

Eye - Conjunctivitis

Diagnosis of Roundworms

Adult roundworms are long and can be seen in the dogs stool. Eggs can only be detected with a microscope. Detection techniques are dependent on the body organ that is affected. Internal organs may have lesions. Eye worms can sometimes be diagnosed with an eye exam.

Treatment of Canine Roundworms

Treatment of roundworm is not considered to be difficult. Many roundworm drugs allow your dog to pass the worms during a bowel movement. No treatments kill the roundworm eggs, however once cured, common preventatives can be used such as ProHeart.

Each type of worm has a recommended prescription drug such as Fenbendazole and pyrantel.

Prevention of Roundworms in Dogs

It is difficult to kill Roundworm eggs. The best way is to add a bleach solution (1%) to water and clean the area where your dog does its bowel movements. Even bleach doesn't kill the eggs, but it does make it easier to wash them away (removes their sticky outer shell).

Roundworms in Humans

Roundworms are the most damaging kind of worm in a human and can come from an infected dog. These worms can affect multiple parts throughout the body. They are treatable, but difficult to diagnose.

The best source for information on worms and humans is Center for Disease Control.