Worms in Dogs: Types, Common Causes & Symptoms

All dog parents cringe when the thought of creepy and gross parasites infesting the bodies of their pups comes to mind. This is why diligent dog owners deworm their dogs regularly.

But even with regular deworming, the dog can get infected between the treatments, and unfortunately, so can you or another family member.

So, even if you are taking all the preventive measures and are deworming your dog on a schedule, it is useful to know what the types of worms in dogs are, what the symptoms are and how they are treated and can be prevented.

Read on to find out everything you wanted (or didn’t want) to know about worms in dogs.

Symptoms that the dog may have worms

Each type of worm affects canines differently, but there are some common symptoms that you should watch for, including:

  • Diarrhea
  • Bloody diarrhea
  • Visible worms or eggs in the feces or the vomit
  • Vomiting
  • Abdominal pain
  • Unintentional weight loss
  • A sudden change in appetite like a loss or increase of appetite
  • A dull and dry coat
  • A general poor appearance
  • Skin irritation and itchiness
  • A pot-bellied or bloated appearance, especially in young puppies
  • Scooting or rubbing its behind on the ground or against the furniture
  • Weakness
  • Lack of energy and lethargy
  • A weak pulse
  • Sore bottom
  • Coughing
  • Wheezing
  • Difficulty breathing
  • None – in some cases, worm infestations can be completely asymptomatic

Common causes for worms in dogs

Dogs of all ages can get worms, but there are some common causes that often lead to worm infestations in canines, including:

Types of worms in dogs

Six main types of common worms can affect domestic dogs. Read more about each type to know how to recognize the symptoms and, most importantly, how to keep your pup safe from infestations.


Roundworms are among the most common worms in dogs. Two types of roundworms can affect canines: T canis (Toxocara canis) and Toxocararis leonine.

T canis is more common among young puppies, which can inherit or get infected via the mother’s milk. This type of worm is zoonotic and thus can be transmitted to humans.

Many puppies are born with roundworms in their tissue, so they need to be checked up by vets as early as possible.

The larvae can be transmitted via the mother’s milk too, and once they reach the intestinal tract will hatch and grow to up to 5 inches in length. If left untreated, they start shedding eggs and do everything possible to remain in the small intestine of the puppy.

They can be diagnosed via examination of fecal samples and can be treated with deworming products and medications.

If left untreated, they can affect the growth and development of the puppies and, in severe cases, can cause death due to malnutrition or intestinal blockage.

Roundworms may also affect adult dogs as well. This can happen if the eggs passed in the stool are ingested. In these cases, the larvae migrate into the infected animal’s lungs and later move up when coughed up and swallowed into the small intestine.

In other cases, the larvae get encrusted in the dog’s tissue, where it remains dormant and activates when the mother dog is pregnant or nursing.

Unfortunately, in these cases deworming the mother does not affect the larvae stuck in the body tissue because most deworming medications work only when the parasites are in the intestines.

The shocking fact is that female roundworms can produce over 100,000 eggs per day. They are protected by hard shells, making them able to remain dormant in the soil for years.

Often, puppies infected with roundworms have a pot-bellied appearance or may vomit or pass visible worms or eggs in their stool.

Toxascaris leonine roundworms do not move around their host’s body and have simpler lifecycles.


Tapeworms transmit to dogs by eating fleas or when the dog scavenges an infected dead wild animal.

They are long and flat parasites with a small head and brick-like segments making up the rest of their body.

The most common type of tapeworm in the US is Dipylidium caninum. The main way dogs get this type of tapeworm is by ingesting fleas that have eaten tapeworm eggs. This is just one of the reasons why you should take flea prevention measures very seriously.

Tapeworms are extremely dangerous. They can reach 4-6 inches in length in the dog’s intestine and have up to 90 segments in their body.

Often the last segment of the tapeworm gets released and can be seen in the stool or stuck around the anus of the infected dog. They look like little rice grains and may even move when they are still fresh. They contain tapeworm eggs, which is why it is essential to pick up your dog’s stool every time and take a fecal sample to the vet if you suspect that it has a tapeworm infestation.

Unfortunately, tapeworms cannot be killed and eliminated with regular over-the-counter deworming products. You should see a vet who will prescribe the appropriate medication or administer treatment to kill and remove the tapeworms from your dog’s body.


Hookworms feed on the dog’s blood which makes them very dangerous to puppies and elderly dogs because they can cause anemia if left untreated.

The dog can get infected with hookworms by ingesting its larvae released in the stool of other dogs outdoors and via the mother’s milk in the cases of Ancylostoma caninum hookworms.

Hookworms are very thin worms in dogs that attach or hook themselves to the small intestine walls and suck on the dog’s blood.

Hookworms are not always visible in the feces, which is why you should take a fecal sample for microscopic examination to your vet if you think that your pup may be infected.

If left untreated, hookworms can cause internal bleeding, leading to blood in the stool and anemia, which is especially dangerous for young puppies, elderly dogs, or dogs with health problems.

The symptoms of chronic hookworm infestation in older dogs are a loss of stamina, weight loss, weakness, bloody diarrhea, and anemia.

The infestation is treated with deworming medication, which your vet will prescribe.

The eggs of the hookworms are spread through the feces of the infected dog. This is why you should be diligent and always pick up and discard your dog’s stool.


Whipworms infest the beginning of the large intestine (cecum) of dogs or the colon, and they pass their eggs to the dog’s feces. These eggs can survive in warm and moist conditions for up to five years, so you should pick up your dog’s stool every time.

An infestation with whipworms can be asymptotic in some milder cases. In severe infestations, the dog may suffer from weight loss, inflammation, diarrhea, stool covered in mucus, and in some cases, anemia.

The adult whipworms are rarely present in the dog’s stool, but when they are, they look like tiny threads with an enlarged end.

Since whipworms shed fewer eggs than other worms in dogs, in some cases, they may not be present in the fecal sample you take to the vet.

This is why you should discuss the other symptoms your dog is showing with your vet to get a proper diagnosis and a treatment for the whipworm infestation.

They are among the worms in dogs that are the most difficult to kill, but they can be eliminated with the proper treatment prescribed and conducted.


There are several types of lungworms, but the most common ones are Oslerus osleri and Angiostrongylus vasorum. These worms in dogs can be life-threatening and are spread by ingesting snails, slugs, or licking contaminated surfaces.

The soil or other areas can become contaminated by an infected dog or other animal coughing up the eggs of the lungworm.

This parasitic worm settles in the lungs and the trachea of the infected dog and can cause severe respiratory problems.

The adult worms create nodules in the windpipe of the infected dog, where they lay their eggs. This can lead to airway obstruction and shortness of breath, a buildup of fluid in the lungs, bronchitis, emphysema, and pneumonia.

A lungworm infestation can be diagnosed with x-rays of the chest and lungs, fecal examinations, a complete blood count, or an examination of a sample of fluid from the dog’s lungs.

The only preventatives and treatments are available with a prescription by a veterinarian. Fortunately, suppose treatment is started in time, and no secondary health problems occur due to the infestation. In that case, the prognosis for the pup is good, as it will cough up the adult worms and eggs after the medication starts working.


These are the most problematic but thankfully the most preventable of all worms in dogs.

Heartworms are transmitted via mosquitoes, and since mosquito bites are nearly impossible to prevent, especially in some areas, it is essential that you give your pup heartworm preventatives regularly.

When heartworm infests a dog, the parasite moves and lives in its heart, where it multiplies and grows. If left untreated, heartworms can kill the dog.

Unfortunately, not only are heartworms difficult to detect, but the treatment for them is expensive, lengthy, and can lead to serious adverse effects.

Heartworms can be diagnosed with a special blood test.

The best way to keep your dog safe from heartworm is to give it heartworm preventive medications. Ask your vet about the preventive medicaments your dog needs to keep it safe from this dangerous parasite.

Diagnosis of worms in dogs

If you notice any worrying symptoms or see worms or eggs in the dog’s stool or vomit, you should go to the vet as soon as possible.

But keep in mind that some worm infestations are asymptomatic, so it is good to take your pup for regular checkups at the vet.

You should take a sample of your dog’s feces for examination, or if you have found an actual worm, place it in a container and take it to your vet.

In some types of worm infestations, the fecal examination may not be sufficient for diagnosing the problem.

In the case of heartworms, or lungworms, your dog may need to have a blood or lung sample examined or X-rays made.

All of the history and the symptoms you can provide to your vet are also incredibly helpful for determining a worm infestation.

The earlier the proper diagnosis is made, and treatment is administered, the lesser the risk of adverse side effects on your dog’s overall health.

Of course, the best way to deal with worms in dogs is through prevention, which means regular deworming with suitable medications.

Treating worms in dogs

After a worm infestation has been confirmed, your vet will prescribe the suitable dog deworming medication needed to eliminate the parasites.

The vet may administer the medicine via injection or orally.

Many deworming medications are considered broad-spectrum and work for a wide range of parasites. They are designed to kill off the parasites but be safe for the dogs.

The different home deworming products come in various forms, including tablets, chews, powders, spot-on treatment, and pastes.

Young puppies should be dewormed at the age of 2-3 weeks old, but since the worm can be transmitted via the mother’s milk, a follow-up deworming procedure is highly recommended a few weeks later too.

Unfortunately, treatment for heartworms is not as simple. Usually, after a blood test has detected the heartworm infestation, the vet will prescribe antibiotics, anti-inflammatory medicines, and monthly heartworm preventive medicaments.

After a month, the treatment for the heartworm can begin. It involves using strong medicine administered by the vet and needs to be given to the dog in a series of three shots for the next two months.

After the shots, the dog needs to be kept quiet and calm for a few months because as the heartworm dies and disintegrates in the heart, it can cause blockage of the blood flow from the heart of to the lungs. This can happen when the heart works harder to pump out blood, like after exercise or running.

After six months, the vet will do another blood test to determine whether the heartworm infestation is cured.

If they are still there, the treatment will need to be repeated.

If they are gone, your dog will be prescribed preventive heartworm medicine for the rest of its life.

How do dog worming treatments work?

In general, the deworming products work by killing the worms infesting your dog’s body. They do not have a residual effect, so your dog can still pick up worms even after the deworming, but if you give it its deworming medication on schedule, any worms will be killed in time before they can cause any serious damage.

Most of the dewormers are broad-spectrum and work for all common worms in dogs. They are easy to use, so dog parents can give them to their dogs by themselves.

You need to give your dog deworming medicine in accordance with its weight for it to be efficient.

The recommended deworming schedule is every three months, but if the dog is at an increased risk of infection, the deworming may need to be done once a month.

Deworming pregnant dogs is not recommended. The earliest time to do that is two weeks after whelping, when you should perform the first deworming of the puppies too.

The puppies should be dewormed soon again after that for any hatched eggs to be killed off and eliminated as well.

Ask your vet for the best deworming plan for your pup to stay on the safe side.

Prevention of worms in dogs

Prevention is the best way to ensure that you don’t have to deal with worm infestations in your pup.

Apart from regular deworming with a suitable medicament, you should also follow the following steps in order to keep your dog free of worms:

  • Protect your dog from fleas and mosquitos, which can carry the eggs of the worms – this can be done with flea collars, tablets, chews, spot-on treatments, powders, and other similar products
  • Apply flea or mosquito spray in your home or backyard
  • Check your dog for worms at least once a year by taking a fecal sample to the vet for examination
  • Puppies need to be checked for worms more often (two to four times a year)
  • Deworm adult dogs once every three months or more often in high-risk situations, and puppies more often
  • Ask your vet for a prescription for heartworm prevention medication which you should give your dog once a month, or ask for a shot that prevents this dangerous worm which can be administered once every six months
  • Always pick up your dog’s poop as soon as possible after defecation
  • If you have a yard, make sure you keep it clean and clean it thoroughly from any fecal matter once a week
  • Do not feed your dog with unprocessed (uncooked) meat or fish
  • Always wash your hands after being in contact with the dog’s stool and after you pet animal
  • Don’t let the dog kiss and lick you or your kids if you are worried about worm infestations
  • In the case of reoccurring infestations, your vet may prescribe prescription worming treatments
  • Don’t share your plate and utensils with your pup
  • Wash raw fruits, veggies, and other plants and foods

What do dog worms look like?

It is useful to know what dog worms and their eggs look like, so you can keep an eye for signs that your pup is infested when inspecting its poop or its rear.

Tapeworms are flat and made of many segments. The ones you are likely to see are the last segments that are released through the anus and contain the parasite’s eggs.

They can be seen in the feces or around the anus of the dog and look like flat white rice grains, which are often joined together. While they are fresh, you may also see them moving. Their movement out of the rear of your dog can cause itching and discomfort.

As for roundworms, they look like spaghetti which are curled and long and have tapered ends. Roundworms can be seen in the puppy’s stool or vomit.

Can humans get infected with dog worms?

You probably consider your dog as part of the family, and you should always keep it healthy because some of the parasites that infect dogs can easily be passed on to humans.

Children and older people with weaker immune systems are especially prone to getting worms from dogs.

Some of the worms in dogs are zoonotic, meaning that the disease carried by the animal can be transmitted either directly or indirectly to humans too.

Worms in dogs like tapeworms and roundworms can be transmitted to people too. This is why it is especially important to regularly deworm your dog and exercise good hygiene after petting the dog and handling its stool.

Hookworm larvae from dogs can also penetrate the human skin and cause scarring and inflammation known as cutaneous larval migrants.

The roundworm egg (ascarid), if ingested, can cause the worm larvae to migrate through the intestine walls into the tissue of the human body. This is called visceral larva migrans and can grow anywhere and to any size.

The Toxocara canis roundworm eggs can remain in the dog’s feces, and if they are ingested by accident can travel through the body to the liver, lungs, muscles, the central nervous system and even to the eyes, where they can cause a loss of vision (ocular larva migrans).

A single Toxocara canis female worm can shed up to 10,000 eggs every day, which are passed through the stool of the infected dog. The eggs are shelled and can remain in the soil or another surface for years. After two weeks of leaving the dog’s body, these eggs become infectious to humans.

Because children are more likely to share a sandbox or a grassy area with an infected animal are at greater risk.

This is why cleaning up immediately after your dog has defecated and regular cleaning of your outdoor space is crucial for eliminating the spreading of the parasitic infection to other dogs, cats, other animals, and humans.

Hookworm larvae can easily be picked up from the ground if you walk barefoot. They can cause intestinal and skin diseases in people.

The hookworm eggs become dangerous to humans after 4-5 days from leaving the dog’s body when they turn into larvae. They can eat through the skin and leave red, itchy and swollen winding tracks under the skin.

As for tapeworms, they can cause very serious diseases in humans known as hydatid, if the person becomes infected by the Echinococcus granulosus tapeworm from dogs. Echinococcus and Taenia can infect humans via accidental ingestion of the eggs. They can cause the formation of hydatid cysts which can occur just about anywhere in the human body, most commonly in the lungs or liver, but can also infest the human brain.

These tapeworms can cause these cysts to grow up to over a foot in diameter and, needless to say, can be extremely dangerous for people. In rare cases, if the cyst ruptures in a vital organ, it can lead to death.

Usually, surgery is required to remove these cysts.

The good news is that humans cannot be infected by dangerous dog heartworms, lungworms, or whipworms.

Since the human body is an abnormal environment for canine worms, the parasites do not know how to behave and their erratic behavior can make people very sick.

This is why you should deworm your dog regularly and go for checkups for worm infestations at least once a year. You should also treat it with flea prevention products because fleas transmit dangerous tapeworm.

Watch your dog when it is outdoors and prevent it from ingesting feces or scavenging on dead animals too. Also, avoid feeding the pup with unprocessed raw meat because it could be infected with parasites and bacteria of all kinds too.

Also, no matter how close you feel to your pup, you should teach your children to wash their hands after petting it, and you should do so too, especially before preparing food or after handling your dog’s stool.

Picking up the feces when walking your dog outside and cleaning up your backyard from stools from your dog or other animals is another way to stay safe from worms in dogs.

Prevention and good hygiene practices are the best ways to rest assured that both your pup and your family are safe from these nasty and in many cases, dangerous dog worm infestations!

Further Reading:

Similar Posts