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Roundworms in Dog Poop? Pictures of These Long White Worms

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roundworm on a table

This article was updated on September 29th, 2023

What Do Roundworms Look Like?

Roundworms (Toxocara Canis) look like long white worms. Adult roundworms look like thick pieces of spaghetti and can be anywhere from 4-6 inches long. Worms this size can be found inside the small intestine of an infected dog. The picture below shows a group of adult roundworms.

roundworms in dogs
Adult roundworms are long white / yellow worms

They are the most commonly found intestinal parasite in dogs and in dog poop. Many dogs will have them at some point in their lives. However, they are especially problematic in puppies. As a veterinarian, I’ll never forget the first puppy I met with roundworms. It was terrible! His belly was so full of worms that he looked like a potbelly pig. He was so infested that he was vomiting and pooping worms. It was traumatizing for both of us! But there is no reason your dog should have to suffer like that poor puppy. Roundworms are TREATABLE!

Read on to find out all things about roundworms in dog poop, including pictures to help you identify what your dog might be suffering from.

What roundworms in dog poop look like

Roundworm eggs are usually hard to see in your dog’s poop. However, it is common to see whole worms in dogs with severe infections. *warning: graphic images ahead*

Below are 2 pictures of severe cases of roundworms in a dog’s poop:

roundworms in a dog's poop on grass
Adult roundworms in a dogs poop.
roundworms in dog's poop
Severe case of roundworms in a dogs poop.

So how do these terrible long worms end up in your dog’s poop?

Well, it’s complicated. Roundworms can be passed from infected to uninfected dogs in several ways. One way they are passed is from a mother to her puppies. When a pregnant dog is infected with roundworms, (or she has encysted larvae in her body from a previous infection), she can pass the larvae stage of the roundworm through the placenta to the developing puppies or through milk when puppies are nursing. It is critical to have your vet deworm any pregnant dogs and puppies, even if you haven’t seen worms in their stools. 

The two most common species of roundworms seen in dogs are Toxascaris leonina and Toxocara canis. When roundworm eggs are passed in the stools, Toxascaris is infective within a week and can live for many months. Toxocara eggs are passed into the stool, but take up to a month to mature and become infective; with these roundworms, fresh feces are NOT infective, but the contaminated soil will be. 

worms in the soil with a dog digging

Roundworms end up in your dog’s poop in 1 of 2 ways:


When a puppy eats a roundworm egg it travels to the intestine and hatches into larvae. The larvae end up in the liver and lungs and are eventually coughed up and swallowed by the pup. After being swallowed, they move back into the small intestine where they mature and reproduce. The eggs produced by the adult worms in the pup’s stomach then end up in the pup’s poop. Learn more about worms in a puppy’s poop.

Adult dogs:

In adult dogs, ingested eggs hatch into larvae and end up in the dog’s brain and muscle tissue. This is usually not a problem, as male adult dogs don’t usually have symptoms. However, in adult females, and pregnant dogs, the roundworm larvae enter the fetus where they stay packed in little cysts until she gives birth. When the puppies take their first breath, the larvae break their way into their airways, bowels, liver, and lungs, and are swallowed. Once in the stomach, they reproduce and the eggs eventually come out in your dog’s poop. Adult female dogs can also transfer roundworms through their breast milk to their puppies.

What are the symptoms of roundworms in dogs?

Symptoms are different for every dog. Puppies usually show the most symptoms and adult dog’s sometimes don’t show any at all.

Some of the symptoms of roundworms in puppies are:

  • Poor or stunted growth
  • Weight loss
  • Large potbelly-like stomach
  • Worms in stool
  • Worms in vomit – less common unless roundworm infection is severe
  • Coughing
  • Diarrhea
  • Mucus in poop
  • Erratic appetite
  • Weak immune system
  • Seizures-in severe cases
  • Pneumonia-in severe cases
  • Death-in severe cases

Symptoms of roundworm in adult dogs: 

Dogs over 6 months of age do not usually show symptoms. This is because larvae swallowed by adult dogs are trapped in cysts in the dog’s muscles. Very few roundworms make it to maturity. Roundworms in adult dogs are hard to diagnose because they usually don’t have adult worms in their poop. Which is why fecal tests are recommended. Fecal tests can find eggs and parasites in your dogs poop at the microscopic level.

How to make sure that the worms in your dog’s poop are really roundworms:

There are many types of worms in dogs. Some of the most common are whip-worm, hook-worm, round-worm, and tape-worm. It is difficult to determine the type of worm your dog has by looking at it and you should never assume your dog has roundworms with a picture. However, it is helpful to know what to look for. Below you will find pictures that show the visual differences between a few common types of worms in dogs.

Disclaimer: This content is not a substitute for veterinary care. Always consult with your vet for health decisions. Learn more.

Roundworms vs tapeworms in dog’s poop

Comparison of roundworms to tapeworms.

Roundworms: are usually white or light brown and can be up 2-3 inches long. They often come out whole (not segmented).

Tape-worms: are flat like tape and they are often seen in segments (about the size of a grain of rice). As tapeworms mature in the intestine, the segments (called proglottids) break off and come out in the dog’s poop. Tapeworms are also caused by flea infestation so your dog will likely be itchy if he has them.

Roundworms vs whipworms in dog’s poop

Roundworms: Roundworms are much wider and rounder than whip worms and they usually aren’t accompanied by bloody diarrhea.

Whipworms: look like tiny pieces of thread and they are larger at one end. They are only 3-6 inches long and can be accompanied by bloody diarrhea.

Comparison roundworms to whipworms.

Hookworms vs roundworms in dogs poop

Hookworms: are white to light brown and very thin, they are so thin that they are barely visible to the naked eye (1/8 inch). They are also known to cause:

  • Dehydration
  • Anemia
  • Inability to exercise
  • Pale gums

Roundworms: are much bigger than hookworms and they can easily be seen in poop and vomit.

How serious is it if your dog’s poop contains roundworms?

All dogs who have worms need quick treatment. Roundworms make puppies extremely uncomfortable. They often suffer from extreme bloating and they don’t usually feel like eating. If you notice any of the following symptoms in your dog, you should visit the vet immediately:

  • Enlarged painful abdomen
  • Diarrhea
  • Vomiting
  • Weight loss
  • Dull hair
  • Coughing

It is never a good idea to hold off on treatment. Puppies who don’t get proper treatment could die from a roundworm infestation.

WATCH: 3 Important Tips To Care For an Old Dog [VET VIDEO]

When are roundworms in a dog’s poop an emergency?

Roundworms in dog poop always need quick treatment. They can make your dog incredibly ill and uncomfortable. Infection with roundworms can even result in death. Some signs your dog needs emergency treatment are:

  • Seizing (shaking)
  • Lethargy (weakness)
  • Inability to keep food down (throwing up as soon as they eat)
  • Severe vomiting
  • Severe diarrhea

Are there treatments at home that can be tried to get rid of roundworms?

There are many over-the-counter deworming medications available to the public. However, these medications each treat specific types of worms. The only way to effectively treat roundworms is to get medication from your veterinarian. There is no way to tell which type of worm you’re treating unless you visit the veterinarian. If you attempt to treat your dog with a home remedy you risk the infection progressing to an emergency. Roundworms and other parasites are one of the easiest, most affordable issues to treat with a veterinarian’s help.

Veterinarian treatment, costs & recovery


When treated right away, both treatment and recovery are quick. Your veterinarian will do an exam, collect a fecal (poop) sample, and send it out to the lab. Results come back within 3-5 days. The fecal results will show if your dog has roundworms, or any other worms or parasites. If your vet suspects that the worms your dog has are roundworms, they may give him medication right there. If they aren’t sure it’s roundworms, they may wait for the fecal results before giving the medication. Once the medication is given most of the worms will be killed within 3 days. Your vet will then recommend regular parasite control and fecal testing.

Cost of treatment for roundworms

Fecal test: The average cost of a fecal test in the U.S. is $25-45.

Deworming: The cost of deworming depends on the type of parasite, the medication used, and your dog’s weight. Puppies will need multiple doses of deworming medication, while adults will only need it every 3-6 months.

Overall, the average cost is $50-100. This includes the exam, the fecal test, and deworming medication. In more severe infections, multiple doses of medication and repeat fecal tests will be needed. If your dog is very ill to the point of needing hospitalization the cost will be much higher.

Common medication used to treat roundworms are:

  • Fenbendazole
  • Ivermectin
  • Pyrantal
  • Milbemycin
  • Moxidectin
  • Piperazine

How to prevent roundworms in the future

Roundworms are prevented by following veterinarian protocols for preventing parasites. Parasite control includes:

  • Regular fecal/parasite testing (every 6 months)
  • Regular deworming, every 3-6 months for adult dogs. For puppies, deworming starts at 2 weeks, then repeated every 2 weeks, until they reach 8 weeks of age.)
  • Remove infected feces from your dog’s environment.

Your veterinarian will send a poo sample out to a lab where they will examine it for eggs and worms. The result is usually back in 3-5 days. The results of the fecal test help your vet decide which deworming medication to treat your dog with. Once you begin medication, the worms should be gone within days. In severe infections or treatment of puppies, deworming may need to be repeated.


Are roundworms contagious to other dogs?

Roundworms can be passed from infected to uninfected dogs in several ways. One way they are passed is from a mother to her puppies. When a pregnant dog is infected with roundworms, (or she has encysted larvae in her body from a previous infection), she can pass the larvae stage of the roundworm through the placenta to the developing puppies. Larvae are also passed through milk when puppies are nursing. This is why it is critical to have your vet deworm any pregnant dogs and puppies even if you haven’t seen worms in their stools. 

Can I get roundworms from my dog?

Yes, humans can get roundworms. Infection occurs when you swallow roundworm larvae. Think of when you let your dog lick your mouth, or when you get feces on your hands, and put your hands in your mouth. In order to prevent chances of infection, wash your hands after handling dogs and puppies, Especially dogs that haven’t been treated with a roundworm preventative. Humans infected with round worms usually don’t have symptoms. However, roundworms can cause a a condition called Visceral Larva Migrans, which causes fever, an enlarged liver, and blindness.

Larvae migrans in the human eye.
Larvae migrans in the human eye. Enlarge picture.

Is it true that children can get roundworms?

Yes, children can get roundworms too. In fact, roundworm infection is the most common type of worm infection in the world. According to an article written by Stanford health, “If a child swallows a roundworm egg, it travels into the intestine and hatches into a baby worm (larvae). Larvae can then pass into the bloodstream and travel through the lungs and into the throat. They are then swallowed again and return to the small intestine. They then grow into adult worms in the small intestine.”

How do dogs get roundworms?

Dogs can pick up roundworms in the following ways:

  • Eating an animal, or, a paratenic host that is carrying roundworms eggs. (ex. birds, rodents, cockroaches, and earthworms.
  • From their mother shortly after birth, through larvae in her milk, or larvae in cysts in her uterus.
  • Eating dirt, or scavenging outdoors where roundworm eggs are present.

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  • Amber Cheney

    Amber has worked as a Veterinary Technician in the United States for over ten years. She is also a certified dog trainer and specializes in fear-free patient care. Her goal is to share her veterinary knowledge with pet owners, so they can make the most informed decisions about their pet's health care.

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