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How to Recognize Roundworms in Dogs

How to recognize roundworms in dogs begins with a dog or puppy who has passed roundworms is a life saver — long, spaghetti-looking white worms in the stools or vomit. At this time, the roundworms in dog feces cause severe infestations of the intestinal worm. Vets suggest that a stool sample needs to be taken  and appropriate treatment from a qualified vet should follow immediately. Roundworms in feces typically develop in puppies under four weeks of age and nursing mothers.

Alias names

Ascarids, Adenophorea, Aphasmidia, Nematoidea Rudolphi, Nematodes Burmeister, Nemates Cobb and Nemata Cobb

Scientific name

Toxocara canis and Toxascaris leonina

Pronunciation of “roundworms”



A female roundworm can lay up to 200,000 eggs in one day, with each hardy egg protected by a very hard shell.


The adult dog roundworm can grow up to seven to 12-inches in length, as an intestinal roundworm or in the stomach, ending with roundworms in feces of dogs.

Typical Signs and symptoms

  • No symptoms usually occur in adult dogs
  • Puppies over 2 months may develop mild vomiting and diarrhea with roundworms in the vomit or feces.
  • Passed roundworms will appear as moving spaghetti
  • In young puppies, roundworm infestations can easily kill them or cause severe illness
  • Failure to thrive and stunted appearance
  • Dull or unhealthy-looking coat
  • Pot belly
  • Anemic

Less common signs and symptoms

  • Development of pneumonia due to a low immune system and 3rd stage larvae in the lung
  • Intestinal obstruction due to large numbers of roundworms

Four ways a dog can become infected with roundworms

  • Prenatal infection – larvae migrates through the placenta when all puppies are in the uterus
  • Roundworms are transmitted in the mother’s milk
  • Roundworms can be ingested through the soil
  • Other animals eat the larvae in the soil [chickens, mice, earthworms, rabbits and cockroaches ] with dogs and puppies ingested an intermediate or transport host.

Life expectancy

The roundworm can live for years in the soil or just a few months.

Life cycle of the roundworm T. canis

  1. Roundworm eggs enter the puppy’s mouth
  2. The eggs hatch in the puppy’s stomach
  3. Larvae are carried to the puppy’s lungs via the circulatory system
  4. The larvae breaks through the capillaries into the air sacs of the lung
  5. The puppy will develop coughing and gagging
  6. Larvae that is in the lungs will crawl up the windpipe
  7. They are swallowed by the puppy
  8. Once in the intestines, they develop into adult worms
  9. Eggs are passed through the stools into the soil

Prescription medication for roundworms in dogs

Drontal Plus




Safe Guard



Vercom Paste

Pyrantel pamoate suspension [Nemex or Strongid) is used for puppies. They are dewormed with the 1st dose at 2 weeks, followed by a dose at 4 weeks, 6 weeks and then 8 weeks. This is referred to as strategic deworming, followed by a heartworm and/or flea control to affect other parasites.

For adult dogs, excellent roundworm dewormers for dogs that kill other parasites are Drontal Plus, Vercom Paste, Telmintic, Safe-Guard (non prescription) and Panacur.

The dewormer Interceptor is the only roundworm medicine for dogs to have an effect on the encysted larvae. This stage of the roundworm becomes activated during the female dog’s pregnancy. The larvae migrates to her placenta and mammary glands. The mother dog is dewormed during the last two weeks of her pregnancy to kill the encysted larvae in her placenta and milk.

Stool samples

A dog should have their stools tested three to four times a years for maintainance. A puppy or dog with roundworms will usually have a water- mucoid diarrhea, vomiting roundworms or roundworms present in the stools. An active roundworm infestation can be detected by a fecal floatation or centrifugation by a veterinarian.

Health concerns for humans

As common intestinal worms that can also live in the stomach, roundworms can make a small puppy under four weeks of age very ill or die if left untreated. However, it the easiest intestinal roundworm to treat.

If a human accidentally inhales an egg from the roundworm [ascarids], the larvae develops in them as in the animal. However, the larvae burrows into the intestinal wall because humans are not considered a definitive host. Instead, they will migrate to the human skin, lungs and liver.

Developing symptoms of roundworms in human are:

  • Abdominal pain
  • Coughing
  • Itching
  • Skin rash with papules
  • Wheezing

Heavier infestations cause the larvae to migrate to the body’s brain, eyes, heart, kidneys, spleen and body tissues. In children infected with worms from dogs  – about 4 to 20% — a syndrome that is called “visceral larva migrans” may develop. Some populations have a 30% occurrence in children age 1 to 11 years of age. The most common age is 16 to 32 months of age, as this is when children put things into their mouth with their hands.

Roundworms from dogs in humans and from human exposure comes from only two sources: roundworms in dog feces or cat feces. This leads to blindness, enlargement of the liver, and pneumonitis (infection of the lung tissue)  and occasionally the removal of the eye. Children and adults should always wash their hands after handling puppies, especially nursing puppies. To prevent household infections, a solution of bleach and water sanitizes the dog’s personal belongings to prevent cross-contamination. How to recognize roundworms in dogs will save a lot of dogs’ lives and prevent children from being infected.

Health care info on is NOT meant to replace a veterinarian visit. (Read our terms of use.)

PLEASE take your pet to a vet immediately at any sign of odd behavior or severe symptoms of illness or injury.

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