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Canine Worms

All About Canine Worms and How to Deworm a Dog Properly

Intestinal worms are among the most common problems of dog owners. Different types of worms may infest your dog, each of them causing different health problems that range from mild to severe. That is why you, as a dog owner, must be armed with adequate information about worms, what they do to your pet, and how to get rid of them.

This article is meant to become a definitive guide about worms in dogs. Here, you’ll understand what worms are and the different kinds of worms that your dog may potentially contract. We’ll also explain how deworming is done and the worming treatments available for your dog.

What Are Canine Worms?

What Are Canine Worms?

Canine worms are parasites that live and thrive inside a dog’s intestines. Most worms stay on the intestinal tract, but some can migrate to other organs inside the dog’s body. Dogs typically contract worms by ingesting the worm’s eggs from contaminated soil, animal carcass, or feces. Some types of worms can also infect dogs through mosquitoes and fleas.

Worms in dogs may cause serious health problems if left undetected or untreated. The worms can severely deprive the infected dog of nutrition, leaving him fatigued and malnourished. Worms may also get their nourishment by feeding on your dog’s blood, producing anemia and related symptoms. Other types of canine worms may even present with serious complications such as heart failure, lung illnesses, and organ damage.

Worms can easily infect puppies and may have severe consequences if not detected and treated promptly. Worm infestations can also be devastating to older dogs, pets with weak immune systems, and dogs with pre-existing medical conditions.

Types of Worms Your Dog May Contract

Types of Worms Your Dog May Contract

Many kinds of parasites infect dogs. But here’s a list of the four most common worm types your dog may contract.

1. Roundworms

Roundworms are the most common intestinal worms seen in dogs. These worms resemble spaghetti noodles or angel hair pasta and have a rounded appearance. Roundworms can grow up to 7 inches long and are typically white, off-white, or pale brown.

There are two main species of roundworms in dogs: Toxocara canis and Toxocara leonina. Toxocara canis is the most common roundworm that infects dogs and puppies. It can be passed on by a mother dog to her puppies while they’re still inside her uterus (transplacental). Puppies may also get the roundworm’s larvae through their mother’s milk. Adult dogs may get Toxocara canis from contaminated soil or by consuming rodents infected with the larvae.

Heartworm is another type of roundworm in dogs. Its scientific name is Dirofilaria immitis and is classed as a parasitic filarial worm. These worms are transmitted through the bite of an infected mosquito.

Heartworms are named as such because these thread-like parasites infect a dog’s lung arteries and heart. Untreated heartworms can cause severe lung disease, congestive heart failure, and eventually, death.

2. Hookworms

Hookworms are parasites that can be fatal for puppies (although not life-threatening to older dogs). That’s because these worms feed on the dog’s blood and tissues along the intestinal walls. They can also detach from the intestines after feeding and migrate to other organs, leaving behind bleeding ulcers that may cause fatal blood loss, especially in puppies.

There are plenty of hookworm species that may infect dogs, but the most common is the Ancylostoma caninum. Other prominent hookworm species include:

  • Ancylostoma braziliense – Can infect both dogs and humans
  • Ancylostoma ceylanicum – A canine and feline hookworm common in Asia; can grow into its adult form in the human intestinal tract as well
  • Uncinaria stenocephala – Cold-weather hookworms; can also infect cats

Generally, hookworms have mouthparts shaped like hooks which help them attach to and feed on the intestinal walls. Puppies can get the worms from their mother’s milk. Adult dogs can get infectious larvae through direct ingestion, skin penetration, and larval leak. 

3. Tapeworms

Tapeworms are flatworm parasites that resemble a ribbon. These worms cling to the intestinal walls and absorb nutrients from the dog’s digestive tract using special segments in their bodies (proglottids).

The tapeworm species often found in dogs is the Dipylidium caninum. Meanwhile, dogs with access to raw carcasses may be infected with the Taenia saginata tapeworm (beef tapeworm in humans).

Your dog may get tapeworms by ingesting fleas that have tapeworm larvae in it. Once a tapeworm matures inside the dog’s body, its tail comes off and comes out in the dog’s feces, infecting the environment surrounding it. Fleas that your dog may shed can also transmit the tapeworms to other dogs and animals.

4. Whipworms

Whipworms or Trichuris vulpis are parasites that live in a dog’s large intestines. As their name implies, they resemble whips and is about 30-50 mm long. These worms have smaller feeding heads and larger tails that serve as their reproductive parts.

Dogs contract whipworms by ingesting infected substances such as water, food, soil, stool, or animal flesh. Mild whipworm cases don’t typically produce symptoms, but severe ones can give your dog weight loss, diarrhea, and inflammation.

Signs That Your Dog Has Worms

Signs That Your Dog Has Worms

Various signs and symptoms can signal that your dog has been infested by worms. Watch out for these symptoms, grouped according to the worm type that causes them:


  • Stunted growth (for puppies)
  • Dull coat
  • Pot-belly
  • Coughing due to eosinophilic pneumonia
  • Diarrhea with mucus
  • Vomits and stools with visible roundworms (for severe cases)

Meanwhile, heartworms produce symptoms such as persistent mild cough, weight loss, decreased appetite, and fatigue even after mild to moderate activity. Left unattended, heartworm symptoms may quickly progress to a swollen belly, heart failure, and caval syndrome


  • Diarrhea
  • Weight loss
  • Loss of appetite
  • Tarry or bloody stools
  • Skin irritation on the feet in between toes
  • Weakness and pale gums (anemia signs)
  • Coughing due to migration of larvae to the lungs (for severe cases)

Note that these symptoms may show up only in heavy infections.


  • Scooting or dragging his butt across the ground
  • Constantly licking or biting the anal area
  • Vomiting and weight loss (for severe cases)


  • Blood or mucus in the stool
  • Diarrhea
  • Weight loss
  • Weakness and pale gums suggestive of anemia (for severe or chronic cases)

How to Deworm a Dog

How to Deworm a Dog

Your dog’s vet will typically run a series of stool exams to check if worms are really present and what kind of worms have infested your dog’s body. Fecal flotation, blood tests, radiographs, ultrasounds, or echocardiograms may be needed if your vet suspects heartworm in your dog.

Now, a worming treatment will be given after your vet confirms the diagnosis of worms in your dog. These medications are targeted to specific worm types and will help get rid of them completely.

Certain combination drugs can effectively eliminate tapeworms, hookworms, roundworms, and whipworms all at the same time. Your veterinarian can help you find the best combination product depending on your dog’s infestation and condition.

Roundworms Treatment

To treat roundworms, your vet will prescribe one to three doses of worming treatment. The medications your vet will give may include:

  • Pyrantel
  • Fenbendazole
  • Piperazine
  • Milbemycin
  • Moxidectin

Adult worms will instantly be killed and eliminated from your dog’s body after the initial dose/doses. Follow-up dosages will be prescribed to kill new generations of adult worms that were not addressed during the initial worming treatment.

Puppies with roundworms are typically given Pyrantel for two doses at three and six weeks old. They are routinely dewormed in conjunction with their first few puppy vaccinations, whether worm eggs are seen on their feces or not. That’s because puppies are most susceptible to roundworm infection.

Heartworms Treatment

Several cases of heartworm disease are diagnosed already in their advanced stage. It could still be treatable, but note that the worms have been on your dog’s body long enough to cause substantial damage to vital internal organs such as your dog’s lungs and heart.

Melarsomine is an injectable medication given to kill adult heartworms. Your veterinarian will give your dog a specific schedule of injection, depending on the illness’s severity. Typically, a heartworm-infested dog will receive one initial injection, followed by a rest period of 30 days. Then, two more doses are given 24 hours apart.

Your dog will also be given a combination of imidacloprid and moxidectin to kill the heartworm larvae. The treatment is applied topically and absorbed into the bloodstream where the heartworm larvae reside.

Once a dog finishes his scheduled heartworm treatment and test results show that heartworms are completely eradicated from his system, he’ll be placed on regular heartworm preventatives for his entire life. The dog will also be tested for heartworm annually.

Hookworms Treatment

Hookworm treatment for dogs includes the administration of any of the following medications:

  • Fenbendazole
  • Pyrantel
  • Moxidectin

Milbemycin may be given to treat A. caninum hookworms. Nitroscanate is approved for hookworm treatment in Canada, but it is unavailable in the United States. This medication is used to treat A. caninum and U. stenocephala hookworms. 

These combination drugs may also be used to combat A. caninum and U. stenocephala hookworms:

  • Ivermectin + Pyrantel
  • Ivermectin + Pyrantel + Praziquantel
  • Moxidectin + Imidacloprid
  1. ceylanicum hookworm species is treated with combination products containing praziquantel, febantel, and pyrantel embonate. This combination drug is available in Australia. Meanwhile, A. braziliense is treated with ivermectin.

Puppies infected with hookworms from birth can start treatment from 2 weeks of age onwards. The treatment will last for approximately 12 weeks. Pregnant dogs with hookworms are treated with fenbendazole from pregnancy day 40 until 2 days after giving birth to her pups – this greatly reduces transmission of hookworms to her puppies.

Tapeworms Treatment

Praziquantel is the worming treatment of choice for most types of tapeworms. The drug is given orally for two days to dissolve the parasites from the intestines of your dog. Injectable praziquantel may also be used at your veterinarian’s discretion.

Your veterinarian may also prescribe fenbendazole to treat Taenia saginata tapeworm species. For D. caninum tapeworms, epsiprantel and nitroscanate are also effective alternatives.

Flea medications are also given in conjunction with tapeworm treatments. Hence, it’ll take 3-4 months before tapeworms and fleas are eradicated in your dog.

Whipworms Treatment

Whipworm treatments vary depending on your dog’s degree of infestation. Fenbendazole is the drug of choice to eliminate T. vulpis whipworms. The vet can deworm a dog using fenbendazole in two ways:

  • Giving the drug every 24 hours for 3 days upon diagnosis, then 3 weeks after, then 3 months after.
  • Giving the drug every 24 hours for 3 days every month, starting from the time of diagnosis until 3 months after.

Fenbendazole can be mixed with food and given even when there are no whipworms readily seen in a fecal exam.

Read more about Fenbendazole here: Your Complete Guide to Canine Deworming Using Fenbendazole for Dogs

Other worming treatments effective against T. vulpis whipworms include:

  • A combination drug of praziquantel + pyrantel pamoate + febantel, given as a single dose from diagnosis time until 3 months after diagnosis
  • Heartworm preventatives approved for T. vulpis treatment (Milbemycin oxime + Lufenuron), given monthly for three months at the least. However, long-term treatment is advised to give continuous protection from both whipworms and heartworms

Now, several treatments for all kinds of worms are completed at your veterinarian’s office. Understandably, your dog may feel upset or apprehensive. Reassure your dog by gently repeating affirmative commands and saying “good dog” more often [1]. This will help calm your dog as he receives his treatments. Note that your trained dog’s brain can perceive words similar to that of a human brain [2], so your dog will know you’re reassuring him.

What Happens After Deworming Your Dog?

What Happens After Deworming Your Dog

Make sure your dog swallows the entire oral deworming medication for it to be truly effective. He may try to spit out the deworming agent right after giving it to him. Some dogs also vomit and bring back the tablet up. In these cases, you may ask your vet when to give the next dose – this may vary depending on the medication and the severity of the worm infestation.

You may notice worms in your dog’s feces a few minutes or hours after the treatment. Don’t panic – this is completely normal and is a good sign that the worms are finally dying and coming out of your dog’s body!

Meanwhile, puppies will eliminate the worms through their feces, just like in old dogs. However, puppies with severe infestations may throw up and vomit these worms after treatment.

Keeping Worms at Bay for Good

Keeping Worms at Bay for Good

To deworm a dog means killing off all living worms inside the dog’s gut and body using medications. However, your dog is still at risk for reinfection once the treatment finishes. As such, continuous deworming is needed to keep the risks of worm infection low. The recommended worming schedule is as follows:

  • Puppies – Deworm the pups at 2, 4, 6, and 8 weeks. Then, deworm again at 12 and 16 weeks. Next deworming is done at 6 months and 1 year. Then, the dogs are dewormed following the adult schedule.
  • Adults – Dogs must be dewormed twice a year for life. Dogs who love to hunt may be dewormed more frequently, depending on you and your vet’s consensus.
  • Newly-acquired dogs – No matter what the age, your new pet must be treated as if he has parasites. Hence, you should have your dog dewormed immediately. Repeat the deworming in 2 weeks, then deworm as an adult.

Also, heartworm checks and preventative treatment must be done annually for all dogs. This is to prevent the deadly heartworms from infesting your dog at any time throughout his life.

The Takeaway

Your dog can be infested by many worms such as roundworms, heartworms, tapeworms, whipworms, and hookworms. Proper diagnosis is key to the correct treatment methods to kill specific types of worms. Regular deworming and heartworm preventatives are also recommended to keep worms at bay for the rest of your dog’s life.



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  11. Bowman D., Legg W., Stansfield D., (2019). Efficacy of Moxidectin 6-Month Injectable and Milbemycin Oxime/Lufenuron Tablets Against Naturally Acquired Trichuris vulpis Infections in Dogs. Vetfolio.
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  15. Wikipedia. Trichuris vulpis. Wikipedia Org.
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