Dog Tips

How Do Dogs Get Worms?

No one wants to think about their dog having worms. These nasty parasites are an unpleasant part of dog ownership, but one that responsible preparation and education can help.

Knowing how to promptly identify signs of worms in your dog and taking proper steps to minimize risk are two important ways responsible pet parents can protect their dog.

Today, Spot Pet Insurance is here to help! We’re laying out the details you need to know to keep infection far from your dog. You’re going to learn about the types of worms, causes, symptoms, and treatments before the day is done.

What kinds of worms could infect dogs?

Worms are a tiny type of parasitic creature that can infect dogs, other animals, and even humans in some cases. Species such as tapeworms and heartworms are especially notorious.

Nonetheless, the dirty details about worms aren’t exactly common knowledge. First, let’s look at the types of worms that might infect dogs.

We can break these worms into two categories. Intestinal worms are the most common worldwide and include four of the five types of worms we find in dogs: roundworms, hookworms, tapeworms, and whipworms.

The fifth and final kind of worm in dogs is heartworms. Standing alone from intestinal worms, heartworms are the most dangerous. Thankfully, proactive prevention steps are also available.

What causes worm infection in dogs?

Worms could come from many sources, but one of the most common ways dogs come across these pests is to come in contact with a contaminated source of some kind.

Infection by touch is rare but not impossible. What is more common for dogs is to be infected by ingesting something contaminated. Feces are the main source of worm infection in dogs, especially hookworms, roundworms, and whipworms. Whether these worms are living in dog feces or wild animal feces, a single taste of these feces could lead to infection.

The soil itself could also be contaminated, especially around places where feces are common (like sandboxes that roaming cats use as litter boxes). Some dogs may lick their paws or fur and become infected due to traces of contaminated soil and/or feces.

Wild animals and their eggs might also be infected with different types of worms. Contact with or consumption of either could infect your dog as well.

This goes for larger animals, such as birds or squirrels, but also the tiny pests we find everywhere. Mosquitos, for example, are the source of heartworms (transmitted when your dog is bitten), while fleas (typically ingested during grooming) can transmit tapeworms.

Worm eggs can survive for long periods, even without a live host. Hookworm larvae or eggs can live in soil for a few months, for example, while whipworms can survive in a similar environment for up to five years.

What are the symptoms of worms in dogs?

Ultimately, each type of worm induces different symptoms, but some common symptoms may point to worm infection of some kind, including:

  • Diarrhea

  • Vomiting

  • Lethargy

  • Bloody or irregular fecal matter

  • Irritated bottom

  • Weight loss

  • Abdominal pain

  • Poor coat quality

  • Potbelly

  • Excessive drinking (dehydration)

  • Anemia

  • Difficulty passing stool

Unfortunately, most of these common symptoms aren’t necessarily clearly indicative of worms since they are also tied to many other health conditions.

We can look at specific patterns of symptoms found with each type of worm infection to help narrow things down. But ultimately, tests by a professional veterinarian (a DVM) are the best path forward for diagnosis. If you notice any suspicious signs, talk to a trusted vet as soon as possible.

Symptoms of roundworms

Roundworms are the easiest type of worm to identify since they should be visible in a dog’s stool if present. Roundworms might also be present in vomit or even regurgitated on their own. Two types of roundworms that canines might come into contact with are Toxocara canis and Toxascaris leonina.

A dog infected with roundworms will also likely suffer diarrhea, lethargy, reduced coat quality (dullness), some weight loss, and an unusually distinct potbelly.

Roundworms are especially dangerous for puppies since they can stall growth but threaten dogs of all ages as well. Hookworm and roundworm larvae can be passed from pregnant or nursing adult dogs to their young puppies. Sometimes, dogs accidentally eat roundworm eggs.

Symptoms of hookworms

Hookworms are usually too small to be seen in feces by the naked eye but can be detected by tests conducted by a veterinarian.

Symptoms typically include bloody diarrhea, weakness, lethargy, and anemia. Anemia is a dangerous condition in which a dog lacks blood to carry oxygen to vital organs. Hookworms are especially dangerous when anemia is present and can be fatal if left untreated.

Symptoms of tapeworms

To the naked eye, tapeworms look like little grains of rice, typically attached to your dog’s fur around their rear end but possibly in their feces as well. They might also be present in long segments that look more like a traditional “worm.”

Other than visually identifying these parasites, you might also discern tapeworm infection by signs of an irritated bottom, such as excessive scooting, scratching, licking, or itching. Tapeworm eggs attach themselves to a dog’s small intestine after accidental ingestion.

Symptoms of whipworms

Whipworms are sometimes, but rarely, seen in feces. They are typically too small to be detected by the naked eye. Symptoms, however, may be more clear.

A dog infected by whipworms typically experiences chronic weight loss, inflammation, and bloody diarrhea, sometimes with a visible coating of mucus. Anemia is also possible in severe cases, making whipworms another hazardous type of worm. Whipworms are considered “zoonotic” or a threat to humans.

Symptoms of heartworms

Unique from intestinal worms, these parasites are the most preventable but also the most dangerous. Heartworms aren’t going to show up in your dog’s feces because they attach to vital internal organs outside the gastrointestinal tract: the heart and lungs, primarily.

Heartworm symptoms include coughing, difficulty breathing, weak pulse, lethargy, exercise intolerance, abdominal distention, and pale gums. Infection can lead to lung disease, heart failure, and organ damage. If untreated, heartworms can be fatal.

How are worms in dogs treated?

Treatment options for worm infection depend on the type of parasite present. A trusted veterinarian should be in charge of the diagnosis.

In most cases, a pet parent is asked to bring in a stool sample, or a sample is collected during an appointment. Sometimes, it’s possible to see adult worms in an infected dog’s stool, but larvae and eggs can be much harder to see with the naked eye.

Once the type of worm is known, deworming medications are most often prescribed. In some cases, treatments take only a few weeks, but it can take a few months or longer in others. Some vets will start deworming pups that are two weeks of age.

Heartworms are especially difficult to treat, with treatment being lengthy, expensive, and disruptive to regular life. For this reason, it’s generally recommended to be diligent in preventative treatment against heartworms and regular testing for possible infection. Your vet may recommend monthly heartworm prevention medications to ward off an intestinal parasite infestation.

In any case of worms, the best way forward is to partner with a licensed veterinarian. Over-the-counter solutions are unpredictable, especially since each dog is different and may have unique needs or risks.

Pet health is our priority

We hope this guide has helped you better understand worms and how to protect your fur family from them!


  • Intestinal Worms In Dogs | Blue Cross

  • Worms in Dogs: Prevent, Diagnose, and Treat Different Types of Worms | AKC

  • Roundworm Infection in Dogs | VCA Animal Hospital

  • Roundworms & Hookworms | CDC

  • Anemia | Cornell University College of Veterinary Medicine

  • Keep the Worms Out of Your Pet’s Heart! The Facts about Heartworm Disease | FDA

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