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Can You Tell if Your Puppy Has Worms?

Puppies are so sweet and innocent with their cute little noses and playful paw swipes. It’s hard to imagine they could have intestinal worms!

The truth is new puppies are often born with worms that they contract in utero.

Since the health risks of parasites in puppies far outweigh the risk of deworming, veterinarians suggest a schedule of deworming every 2 weeks from birth until the puppy is 3 months of age.

After that, pet owners are highly encouraged to continue deworming every 3 months for life.

In this post, we’ll explain the signs of worms in puppies, the common types of worms found in puppies, diagnosis, treatment options, and prevention.

Most Common Worms in Puppies

It’s important to have a basic understanding of the most common worms in puppies.

Keep in mind that some puppies don’t show any signs that they have worms. In other cases, you might see them in your puppy’s poop or notice changes in the appearance and energy of your dog.

Sadly, intestinal parasites can stunt growth in puppies. Some can even cause life-threatening anemia. The following are the most common types of worms found in dogs.

Roundworms (Nematodes or Ascarids)

Roundworms (toxocara canis) are the most common intestinal worm in dogs. Both humans and animals are at risk because of how tough it is to rid the environment of the eggs.

Roundworms are intestinal parasites that live in the small intestine. Dog owners may see them in their dog’s vomit or feces where they will appear white or light brown. Roundworms may be several inches long and look like strings of spaghetti.

Can humans catch roundworms from dogs? Yes, they can.

Roundworm eggs can be found anywhere in the environment, whether it’s from contaminated soil in your backyard or through the infected tissues of a mouse. Dogs can easily get roundworms just by swallowing soil or encountering contaminated feces.

The cycle continues as the dog then passes roundworm eggs or larvae back into the environment through their own feces. Once an area is contaminated with roundworms, they are very hard to get rid of.

If pups less than 3 months old eat the eggs that have been in the environment for at least 4 weeks, the eggs hatch, releasing larvae that penetrate the intestinal wall. The larvae migrate through the liver, reach the lungs via the bloodstream, are coughed up, swallowed, and mature to egg-producing adults in the small intestine.

PEREGRINE.ANDREW. “Gastrointestinal Parasites of Dogs – Dog Owners – Merck Veterinary Manual.” Merck Veterinary Manual, Accessed 24 Feb. 2023.

Puppies explore and learn about the world around them through sight, smell, hearing, and touch. Unfortunately, that learning process sometimes involves swallowing things that may be contaminated with worms.

Newborn puppies can’t stray far from their mothers, but that doesn’t mean they are out of the proverbial woods. If the dam, or the mother, has a roundworm infection, the puppy will either contract those worms while in utero, or shortly after birth through the mother’s milk.

Puppies can contract worms in utero or through mother's milk

Signs of Roundworms in Puppies

Signs of roundworm infection in puppies can vary depending on the severity of the infection and the age of the puppy. In fact, some puppies may not have early symptoms.

It’s best to assume your new puppy has worms and have him or her dewormed according to the veterinarian’s suggested deworming schedule. Worms are very detrimental to the health of newborn puppies.

If your puppy hasn’t been dewormed and you’re concerned, take note of the following signs:

  • Visible large, pale, spaghetti-like worms in the stool
  • Poor growth and weight loss
  • Pot-bellied appearance
  • Vomiting
  • Diarrhea
  • Dull coat
  • Lethargy
  • Cough secondary to pneumonia in young puppies

Hookworms in Puppies

Hookworms are like roundworms and tapeworms in that they live in the digestive system. They attach to the lining of the intestinal wall and feed on your dog’s blood. This is a serious threat to puppies who may not survive the blood loss.

Hookworms, like roundworms, are found all over the world. In the United States, they are most prevalent along the East and West coasts.

You’d think your dog must swallow either the eggs or the larvae to become infected. While that is true, hookworms have other means of infecting dogs. For example, they can penetrate your dog’s skin or find their way to your dog’s digestive tract when he or she is licking and grooming.

Hookworms are another parasite that can infect puppies through their mother’s milk. This is because the adult female hookworms lay their eggs within the intestines of the mother dog. They then hatch into larvae and migrate to the mammary glands where they are excreted in the milk.

Hookworms migrate to the puppy’s lungs.

Once inside the body, the hookworm larvae migrate through the bloodstream to the lungs, where they are coughed up and swallowed. From there, they reach the small intestine and attach themselves to the intestinal wall using their hook-like mouthparts.

Once attached, the hookworms feed on their host’s blood, which can cause anemia and other health problems if left untreated. The hookworms also produce eggs, which are passed out of the host’s body in their feces, completing the lifecycle.

Puppies that live in unsanitary or crowded conditions are at a higher risk of being exposed to contaminated soil.

Puppies can become infected a few different ways.

Puppies can also become infected with hookworms by encountering other infected animals. This can happen if the puppies play or socialize with other dogs that have hookworm infections, or if they are exposed to infected feces.

Signs of Hookworms in Puppies

Signs of hookworms in an infected dog can vary depending on how bad the infection is. Hookworms cause blood loss. As a result, signs of infection include:

  • Anemia
  • Pale gums
  • Blood diarrhea
  • Itchy paw
  • Weakness
  • Poor growth
  • Weight loss

Acute hookworm infections can result in extreme anemia. These puppies may have bloody or black tar-like diarrhea and can die because of the infection.

Tapeworms in Puppies

You may not realize this, but there are several types of tapeworms. The most common tapeworm in dogs is known as Dipylidium caninum. They are flat, segmented intestinal worms that belong to the cestode family.

Puppies can get tapeworms by ingesting fleas that are infected with tapeworm eggs or by ingesting the tissue of infected animals such as rodents, rabbits, or birds. Tapeworms need a host (a flea, for example) before they can infect dogs.

If a puppy swallows a flea infected with tapeworm eggs, the tapeworm eggs can be released into the puppy’s digestive system where they grow into adult worms. They use hook-like mouthparts to attach to the wall of the small intestine and can grow up to 11 inches long.

The rice-like segments (known as proglottids) seen in a dog’s feces are parts of the adult tapeworm. You may even spot them moving around the dog’s anus. Once the segments are passed, they dry out and break open, releasing as many as 20 fertilized eggs.

Signs of Tapeworms in Puppies

The truth is that there are usually no obvious signs of tapeworms in young puppies or adult dogs. Some puppies will rub or scoot their bums along the ground. You might even notice your dog biting or licking his anus due to the irritation.

This is due to the itching caused by the worms.

So how do you know if your puppy has tapeworms? You might notice them when you look under your dog’s tail near the anus or see the rice-like segments in your puppy’s feces.

Undiagnosed tapeworm infections could cause the following symptoms:

  • Lethargy
  • Distended abdomen
  • Vomiting
  • Diarrhea
  • Dull coat
  • Weight loss
  • Visual signs of tapeworms in the dog’s feces

Whipworms in Puppies

Whipworms (Trichuris vulpis) are a type of intestinal parasite that can affect dogs. The name, whipworm, refers to their whip-like appearance. They measure about 1/4 inch long and have a thick front-end with a long thin back end.

Whipworm eggs are shed in the dog’s feces and can survive in the environment for several months, making it easy for puppies to pick up the parasite by ingesting contaminated soil or other materials.

Once inside the puppy’s intestines, the whipworm eggs hatch, and the larvae grow into adult worms that attach themselves to the intestinal wall and feed on the puppy’s blood.

Puppies are at risk of intestinal worms

Signs of Whipworms in Puppies

The symptoms of whipworm infection in puppies can range from mild to severe and may include any or all of the following:

  • Chronic diarrhea
  • Weight loss
  • Anemia
  • Blood in stool

Heartworm in Puppies

Heartworm disease is a serious and potentially fatal condition caused by a parasitic worm called Dirofilaria immitis. The disease is transmitted through the bites of infected mosquitoes. The parasite can be transmitted from animal to animal by mosquitoes.

When a mosquito bites an infected animal, it picks up the young heartworms called microfilariae. The microfilariae develop into infective larvae within 2 weeks. The parasite is transferred to your dog when the infected mosquito takes a bite.

The larvae mature into adult heartworms within 6 months. Initially, they spend about 3 months circulating through your dog’s body until they reach the blood vessels of the lungs. During the last 3 months, the worms continue growing. Female heartworms can grow as long as 14 inches.

If male and female heartworms are present, they will mate, causing even more heartworms to infect your dog. Adult heartworms can live for 5 to 7 years in dogs!

Heartworms damage your dog’s heart and lungs.

Unfortunately, heartworm has been found all over the United States and in some parts of Canada. The good news is that it is preventable. The best way to ensure you’re getting the best heartworm prevention for your dog is to speak with a veterinarian.

There are different types of heartworm prevention medications including once-a-month chewable tablets, once-a-month topical applications, and bi-annual or annual injection. Ivermectin is commonly used to prevent heartworms in dogs and cats.

How can I tell if my puppy has heartworms?

Recently infected dogs may not show any signs. As the infection progresses, your dog may exhibit the following signs:

  • Cough
  • Lethargy
  • Loss of appetite
  • Difficulty breathing

Coccidia in Dogs

Coccidia are single-celled gastrointestinal parasites most often found in puppies. All it takes for a dog to become infected is by swallowing contaminated soil, especially where there may be dog feces.

The disease caused by this parasite is known as coccidiosis and is considered dangerous in puppies. The reason for this is because it can cause severe diarrhea leading to dehydration and possibly death.

Coccidia infections can be prevented by clearing feces from the yard or other areas in the environment.

Other Types of Worms that Can Infect Dogs

Flukes, including the types listed below, should also be considered when diagnosing parasitic infections in dogs.

Flukes (Trematodes)

Flukes are categorized by the organ they affect. Examples include:

  • Lung flukes
  • Intestinal flukes
  • Hepatopancreatic flukes (rare)
  • Blood flukes (also known as “swimmer’s itch”

According to Today’s Veterinary Practice, fluke infections of companion animals have decreased in recent years. That said, there may be cause for a veterinarian to consider fluke infections based on geographical area and lifestyle.

Clinical signs of fluke infection vary depending on the type.

Diagnosing Worms in Puppies

Veterinarians diagnose worms in puppies by performing a fecal examination, which involves analyzing a small sample of the puppy’s feces under a microscope to look for the presence of worm eggs or larvae.

Fecal Flotation

If the intestinal worms aren’t mature enough to produce eggs, a fecal test may produce a false negative. Sometimes multiple fecal tests are required to successfully diagnose a parasitic infection.

Other Tests

Fecal flotation is the first step in diagnosing parasites in dogs. If test results continue to come back negative but the dog is showing signs of a parasitic infection, other tests may be performed.

Other options include a fecal wet mount, concentration methods, stool preservatives, or a fecal Baermann.

Treating Worms in Young Puppies

The treatment of worm infestations in puppies typically involves the administration of deworming medications. The choice of medication depends on the type of worm infestation and the age and weight of the puppy.

Some commonly used deworming medications for puppies include:

Fenbendazole (registered, trademark names Panacur, Safe-Guard)

Fenbendazole is a prescription-based, broad-spectrum antiparasitic medication commonly used to treat and prevent various worm infestations in animals, including dogs and cats. It works by disrupting the metabolic processes of the worms, leading to their death.

This medication is effective against a wide range of intestinal parasites. Although this medication is well-tolerated by most animals, there can be mild side-effects including:

  • Vomiting
  • Diarrhea
  • Loss of appetite

Pyrantel pamoate (registered trademark, brand names Nemex and Nemex2)

Pyrantel pamoate requires a prescription. This antiparasitic medication works by paralyzing the nervous system of the worms. The worms are then expelled from the pet. The drug effectively eliminates many types of intestinal parasites except for tapeworms and whipworms.

The medication is well-tolerated by pets but, in rare cases, may cause side-effects including:

  • Vomiting
  • Diarrhea
  • Loss of appetite

Milbemycin oxime (registered trademark, brand name Interceptor)

Milbemycin oxime is commonly used to prevent and control heartworm disease in dogs and cats. It works by interfering with the nervous system of the parasites, leading to their death. It’s also effective against a variety of intestinal parasites including roundworms, hookworms, and whipworms.

This medication is by prescription only. The veterinarian will determine the appropriate medication and dosage based on the puppy’s age, weight, and type of worm infestation.

Puppies can develop severe anemia from intestinal worms

Supportive Care

In addition to deworming medication, supportive care may be necessary to help the puppy recover from the infestation.

This may include providing a high-quality diet to help the puppy regain weight and strength, as well as regular veterinary checkups to monitor the puppy’s progress.

In severe cases, hospitalization may be required to provide the puppy with intravenous fluids and other supportive therapies.

Preventing Worms in Puppies

Preventing puppies from getting worms is essential for their health. In addition to regular deworming through a licensed veterinarian, keep your dog away from feces, raw meat, and the carcasses of dead animals (mice, for example).

There are a variety of over-the-counter and prescription-based preventative treatments available. We highly recommend speaking with a veterinarian to narrow-down the best choice for your dog.

“Home remedies” are not recommended for the prevention or treatment of worms in puppies.

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Every dog is at risk of contracting worms, particularly if they frequent dog parks, kennels, boarding facilities that do not maintain hygienic conditions, etc. The best way to protect your puppy is to adhere to the deworming schedule recommended by the veterinarian.

Puppies don’t have a strong immune system yet and may not be able to withstand the ravages of intestinal worms. Keep in mind that dogs, including puppies, may not show early signs of infection. It’s better to assume your dog has worms than to wait until they’ve made your dog sick.

Read Puppy Deworming Schedule: Everything You Need to Know by Dr. Lila Batiari for more information.

Works Cited

“Worms.” Worming Your Puppy | Puppy Health | Purina, Accessed 23 Feb. 2023.

“Heartworm Disease.” American Veterinary Medical Association, Accessed 24 Feb. 2023.

PEREGRINE.ANDREW. “Gastrointestinal Parasites of Dogs – Dog Owners – Merck Veterinary Manual.” Merck Veterinary Manual, Accessed 24 Feb. 2023.

Burton, Erin. “Module 2.2: Direct Fecal Smear (Wet Mount) – Clinical Veterinary Diagnostic Laboratory.” Module 2.2: Direct Fecal Smear (Wet Mount) – Clinical Veterinary Diagnostic Laboratory, Accessed 24 Feb. 2023.

“Dog Deworming.” Viera East Veterinary Center, Accessed 24 Feb. 2023.

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