Symptoms and Treatment of Different Dog Worms Types


There are two categories of dog worms that can infest your pet:

  • Intestinal Worms
    - Roundworms (ascarids)
    - Tapeworms
    - Hookworms
    - Whipworms
  • Non-intestinal Worms
    - Heartworms
    - Subcutaneous Worms
    - Lungworms
    - Eye Worms

Most puppies are born with worms which is why deworming is standard treatment. Worms are passed from mother to child internally or through the mother's milk. Worms can also be passed by ingesting feces. Some types of worms are visible in the feces such as roundworms or tapeworms. Tapeworms in particular look like small grains or rice and could be found in the feces or caught in the fur around the anus.

Worms vary in size and how they affect your dog. A dog with worms should always be evaluated by a veterinarian, as most are life threatening if left to multiply and grow into large numbers. There are effective methods available for preventing a worm infestation with the choice of medication dependent on the dog. Over the counter treatments may not work depending on the type of worm, which is why we recommend a visit to the veterinarian.  Treatment involves the use of a dewormer. It will take up to 2 weeks after deworming for worms or eggs to disappear from the feces.

Prevention involves keeping your dog away from areas where worms or their eggs are present in the environment. Some types of worm eggs can last for years in the environment.


Puppies are always treatment for worms from the age of 2 weeks, then every 14 days up to 2 weeks after weaning. They are treated with fenbendazole/febantel, flubendazole, pyrantel or nitroscanate and then receive monthly treatments up to 6 months of age.

To prevent worms spreading from a pregnant dog to puppies, pregnant females are given macrocyclic lactones on the 40th and 55th day of pregnancy or fenbendazole daily from the 40th day of pregnancy continuing until the 14th day postpartum.

The symptoms and effects of worms varies with the type of worm and degree of infestation.

Digestive tract worms can trigger symptoms ranging from no symptoms (asymptomatic) to dogs that show symptoms such as weight loss, anemia and diarrhea. Dogs with symptoms should visit a veterinarian for a physical examination, parasite tests and a complete medical history. 

All digestive tract worms can be spread from one dog to another.

There is also a risk of hookworms and roundworms being transmitted to humans. Most puppies are born with roundworms from the mother while adult dogs contract worms from feces. The one exception is the tapeworm which is spread through an ingested flea. Each type of parasite (another name for worms) has its own characteristics which can be helpful in worm identification.

Most Common Types of Intestinal Dog Worms

As mentioned, there are several types of dog worms which are described below:

Types of Parasitic Worms in Dogs
Parasitic Worms in Dogs

Roundworms (also called Nematodes)

Dog roundworms  knowns as ascarids are the most common type of worms in dogs, especially puppies. The worms are named after their appearance, which in an adult is like a piece of spaghetti. The worm is spread from dog to dog through the ingestion of contaminated feces, or from a pregnant mother through the placenta to the puppy, resulting in a case of puppy worms. The most important specie is Toxocara canis since it's larvae may migrate to humans as well and also can turn fatal for young puppies.

Roundworms can be transmitted from dogs to humans, which is especially a concern for children.


Dog Whipworms are less common than hookworms or roundworms and are found in colon and cecum, a part of large intestine. They are also transmitted by ingesting contaminated feces and affects both puppies and adult dogs. The parasite can cause severe health problems. The worms attach to a dog's intestinal lining and feed on the host's blood. As the worms multiply in the intestine, they can deplete the blood supply, causing a condition called canine anemia. In puppies in particular, advanced cases can be life threatening. No signs are noticed in light infections but can cause inflammation, weight loss and diarrhea with large numbers. Fresh blood might be seen in faeces in heavy infections.


Dog hookworms are also one of the more common dog worms types. The worm is transmitted via ingested contaminated dog feces are through contact with an open wound or skin crack. Hookworms in dogs infect adults more often, and are less common in puppies, the reverse of what is true for roundworms.

Dog Hookworms Life cycle
Diagram: Canine Hookworm Lifecycle
Many dog worms types such as hookworms are ingested via contaminated feces or enter the body through an open wound.


Dog tapeworms (cestodes, Dipylidium) are common. It is not transmitted through feces like other worms in dogs, but instead is passed through the ingestion of a flea, which carries the immature tapeworm. These dog worms take their name from an appearance, with the worms measuring from 4 to 28 inches in length. As the worm grows in the intestines, segments (proglottids) break off. The infection causes no dog worm symptoms and often goes undetected until the owner notices the small, dried up segments migrating out of the rectum. In advanced cases, there could be some weight loss. These worm segments become caught in the fur surrounding the anus or on the outside of fresh feces and can even be seen crawling on the surface. When the worm segments dry out, it leaves behind small hard yellow eggs that can also be stuck to the dog's fur around the anus.

Tapeworm (dog worms types) is diagnosed during a fecal exam performed in your veterinarian's office. There is minimal risk of the worm being transmitted to humans, although it is possible if a person, particularly a child swallows a flea.


Dog Flatworms (also called Trematodes or Flukes): These dog worms types often hook themselves to your dog in their intestines, lungs and liver. They are also passed when a dog ingests infected feces ,and in infected snails and frogs.


Dog Heartworm: Heartworm disease in dogs (Dirofilaira immitis) occurs when worms grow in and around the heart muscle. The disease is spread when an infected mosquito bites a dog. This is one of the most alarming dog worms types since in advanced stages it is life threatening.

Most infected dogs are asymptomatic for months or years, with heart damage slowing increasing over time. Symptoms of dog heartworm includes moderate to severe coughing, particularly after exercise or when excited. In later stages of the disease the abdomen and legs will swell from fluid accumulation as the right side of the heart suffers from developing congestive failure. Other symptoms when a severe case of the disease is present include difficulty breathing (dyspnea). It is rare for a dog to suddenly die from the disorder. Dog heartworm (dog worms types) infection is diagnosed with a blood test. The test can also indicate the severity of the disease which would point to a specific course of treatment. x-rays can also help to confirm the severity of the disease.

Dog Heartworm Picture
Dog Heartworm
Advanced dog heartworm disease in ventricle of heart

It is difficult to treat heartworm in dogs. Treatment can be risky since killing worms that are already in the arteries and heart can be dangerous. Cases are usually classified from high risk to low risk based on the chance of complications that result from treatment. Low risk or class 1 and 2 dog heartworm cases are characterized by having no symptoms and normal heart x-rays. High risk or class 3, 4, 5 canine heartworm patients are already showing symptoms such as coughing and abdominal swelling.

Dog heart worm treatment involves symptomatic therapy to improve heart function and circulation. It is also used to prepare dogs that are treated with an adulticide that kills the heartworm or for surgical removal. Most vets will recommend restricted exercise and cage rest as a way of improving blood circulation. Anti-inflammatory drugs such as glucocorticosterids (prednisolone) can also help to control pulmonary inflammation and thromboembolism. The most commonly used dog heartworm treatment is the medication Immiticide (melarsomine hydrochloride) which is injected into the back muscles of dogs suffering from class 1 - 3 heartworm. A heartworm preventative is only used after the heart has been cleared of all worms.

You can read more by downloading this brochure (PDF) on by the FDA.

Luckily, humans cannot be infected by heartworm.

Dog Ringworm (not a worm, a fungal infection)

Note that ringworm is not due to worms, but a skin fungus. It's name is based on an appearance on the skin that looks like a worm.


Many dog owners believe that dogs with normal feces do not have worms. This is not the case. It is also rare for owners to see worms in the dog stool. Dog worms will infrequently have a loose stool or diarrhea. There is nothing about the appearance or consistency of a stool that will indicate if a dog has worms. The reason is that dog worms may remain in the dog while the only thing that is shed are microscopic eggs that cannot be seen with the naked eye. It should be remembered that life-cycle of worms can take days and even weeks, thus even after treatment and recovery; some dogs may act as carriers. There are kinds of worms, where eggs and larvae can survive up to several months in environment. 

Many dogs with worms will suffer from conditions such as malabsorption or mild malnutrition, which results in weight loss, even though the dog appears to be eating normally. The loss of nutrients due to malnutrition or malabsorption may also cause a loss of quality in the dog's hair coat. The coat may appear to be unkempt or dull.


Most of the time, a dog with worms is diagnosed by a veterinarian after studying feces using a flotation technique. The accuracy of the test is increased if fecal samples collected over multiple days are tested. Eggs of roundworms, hookworms, and whipworms are easily identified.

Most veterinarians will check dogs on a regular basis for the different dog worms types by looking for worms in the stool. Dogs are retested approximately 3 weeks after treatment to make sure that worm removal has been successful.


Treatment for intestinal parasites generally consists of a broad-spectrum dewormer such as fenbendazole (Panacur®), with the addition of praziquantel (Droncit® or Dog Worms®) if tapeworms are also present. Heartworm can be potentially fatal. Low numbers of worms may not cause symptoms until the condition worsens. If left untreated, the disease can cause heart failure and death. Treating heartworm needs to be a considered decision in order to avoid harming the dog.

Dog Worms and Humans

Most dog worms types are species specific. However, it is possible for humans to get intestinal worms from your dog. The problem is more common in children. For example, children that crawl on the ground or play in sandboxes can ingest the eggs that result in worms.

Hookworms can burrow through human skin and are often found in gulf coast states. In a human a hookworm leaves red spots on the skin that are in a trail (caused by the larvae).

Other dog worms types such as whipworms do not live in humans. The most common type of worms in humans, pinworms, are not found in dogs and cats.

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References for Dog Worms Types

IVIS – International Veterinary Information Service
Atkins, Clarke E. DVM, Canine Heartworm Disease: Prevention and Treatment

Heartworm Disease in Dogs; Venco, Luigi

Georgia College of Veterinary Medicine

U.S. Food and Drug Administration