5 Common Types of Worms in Dogs (With Symptoms)

Updated November 18, 2021
owner checking dogs health

The symptoms of dog worms can vary based on the type of worm infesting your dog's body. Learn how to spot whether your dog has worms and get an idea of which type of worms are most likely involved.

Common Symptoms of Dog Worms

A case of dog worms can produce a number of general symptoms that can tip you off to the infestation. These infestations can generally be categorized into "mild to moderate" and "severe" cases. Where your dog's infection falls may depend on the number of worms inside them or the length of time they have been infected. The symptoms typically vary based on the severity, although any worm infestation can present with any of the following symptoms.

Mild to Moderate Worm Infestations

  • Sporadic diarrhea: Often, the first sign owners see with intestinal parasites is diarrhea. This can be persistent diarrhea, or it may come and go. Sometimes it contains blood or mucus.
  • Changes in appetite: A dog may stop eating food or might develop a ravenous appetite with worms.
  • Weight loss: Regardless of the specific type, most dogs with worms experience weight loss. This could be due to a decreased appetite or because the worms interfere with nutrient absorption.
  • Flatulence. If you're wondering whether worms cause gas in dogs, the answer is yes. With any intestinal parasites, digestive issues like flatulence are common.
  • Dull coat: Due to robbed nutrients, the quality of an infected dog's coat tends to decline quickly.
  • Lethargy: Low energy is common with worm infestations. Most dogs are not able to get the nutrients they need, the worms may be feeding on their blood supply, or, in the case of heartworms, the worms interfere with normal cardiac and respiratory function.
  • Cough: Worms living within the heart and pulmonary structures can cause a dog to cough. This could be an intermittent cough or one that is persistent.
  • No symptoms: It's not uncommon for dogs to show no signs at all and still have worms. However, this doesn't mean that the worms aren't wreaking havoc internally.

Severe Worm Infestations

  • Bloated belly: Despite losing weight, dogs with high volumes of worms tend to have a potbellied appearance. This can be commonly mistaken as a full puppy belly, when it's really full of parasites.
  • Worms in stool: When the number of worms in your dog's digestive tract becomes great enough, you may start to see worms in your dog's poop.
  • Worms in vomit: Although this can be alarming, it's also possible for a dog to expel worms in their vomit.
  • Intestinal blockage: Large intestinal worm burdens can actually cause a blockage in the stomach or intestines, which can require surgery. Many dogs with an obstruction experience the inability to pass stools.
  • Anemia: With worm types that feed on blood, dogs can become anemic from significant blood loss. This tends to affect puppies most often, but enough worms could cause anemia in an adult dog. One indication of anemia is pale gums.
  • Death: If left untreated, worms can be fatal.

Symptoms Produced by Specific Worms

vet examine puppy for worms

Now it's time to talk about the specific symptoms of dog worms associated with the most common worms your dog is likely to encounter. Remember, an infested dog may still display any combination of the symptoms mentioned above, in addition to the specific symptoms produced by the variety of worm involved.


Tapeworms are one of the easier worms to identify with the naked eye, and they are generally transferred to a dog by ingesting fleas. In your dog's system, these worms are long, flat, and have a number of segments called proglottids. Occasionally, these worm sections are shed in a dog's stool. You can spot them as rice-like grains in your dog's stool, but you might also find them stuck to the fur around your dog's anus. These living segments can also be found on floors, furniture, and, especially, in your dog's bedding.

Specific symptoms of a tapeworm infestation include:

  • An itchy behind
  • Scooting
  • Restlessness
  • Abdominal pain


Roundworms are identified by their spaghetti-like appearance, and they are sticky in texture. This allows them to easily transfer between dogs and even people. They are also easily detected in a dog's stool or vomit. Roundworms are typically transferred through ingestion of an egg in an infected dog's stool, but they can also be passed from mother dog to puppies within the womb. Because many pups are born infected with roundworms, routine deworming is critical. These worms cause malnutrition by feeding on a dog's intestinal contents.

Specific signs of roundworms include:

  • Bloated belly
  • Weight loss
  • Diarrhea
  • Vomiting
  • Dull fur
  • Visible worms in stool or vomit


Another common parasite, whipworms are transmitted through ingestion of eggs from feces or the environment. They live in a dog's digestive tract where they latch onto the intestinal wall. Whipworms are not visible to the naked eye, but the symptoms they cause are very noticeable.

Look specifically for:

  • Bloody stools
  • Slimy stools
  • Anemia
  • Lethargy
  • Dehydration
  • Gas
  • Severe weight loss


Hookworms get their name from the fact that they attach themselves to the walls of a dog's intestines with their mouths and feed on their blood supply. Dogs can get hookworms by swallowing larvae from another dog's stool, or through skin penetration. Yes, these larvae can penetrate your dog's skin through their paw pads. From there, the worms make their way to the dog's intestines.

Signs of infestation include:

  • Pale gums
  • Weakness
  • Bloody stools/rectal bleeding
  • Anemia
  • Skin dryness or irritation


Heartworms may seem like they belong in a different category from the worms previously described, because they primarily inhabit a dog's respiratory system rather than the digestive tract. However, these are still worms. They are transmitted by infected mosquitos and cause life-threatening damage. Heartworms produce very specific symptoms.

These include:

  • A hacking cough
  • Shortness of breath
  • Fainting spells
  • General malaise/weakness
  • High blood pressure
  • Congestive heart failure

Treatment of Dog Worms

When a worm infestation is suspected, it's very important to identify the type involved so the correct medicine can be used to kill off the worms and eliminate the symptoms. Whips, tapes, hooks, and roundworms are all diagnosed by examining stool samples under a microscope for the presence of worm segments and/or eggs. Common dewormers include, but are not limited to, ivermectin, pyrantel pamoate, praziquantel, and milbemycin oxime. Always allow your vet to decide which medication should be used, as well as the proper dosage and administering schedule. Most wormers require several doses to effectively remove the worm population.

Heartworms are a greater challenge. Prevention of these worms is far more effective, less expensive, and certainly safer than the treatment to get rid of them. Dogs that survive the treatment may still suffer from lasting heart damage. Treatment typically involves a series of immiticide injections and hospitalization may be required.

The Dirt on Worms in Dogs

Catching worm infestations early can protect your dog from the severe symptoms associated with worms and may prevent lasting organ damage. Keep in mind, many of these worms are zoonotic, meaning you or your family can also contract them. If your pup is showing any of the telltale signs of worms, see your veterinarian for appropriate treatment.

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5 Common Types of Worms in Dogs (With Symptoms)