12 Common Signs a Dog Has Worms

If your dog has worms, there may be signs that you may be missing. Some signs aren't easy to recognize unless you know what to look for. Discover what worms are common in dogs and the signs to watch for so that your dog is free of these pesky parasites known for causing many problems.

12 Common Signs a Dog Has Worms

If your dog has worms, there may be signs that you may be missing. Some signs aren't easy to recognize unless you know what to look for. Discover what worms are common in dogs and the signs to watch for so that your dog is free of these pesky parasites known for causing many problems.

Dogs are often infected with worms from a young age. Here are some signs they may have worms and steps to take to avoid them contracting more.

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Worms in Dogs Are More Than a Nuisance!

When a dog has worms, you are dealing with more than just a nuisance. Worms in dogs are categorized as parasites, which means that they cause substantial damage to your dog's body.

Parasites are opportunistic beings that take advantage of hosts in order to thrive, survive and reproduce. Without their host, parasites are unable to live, and therefore they totally depend on their host.

For example, did you know that when you feed your dog, you are ultimately feeding his worms as well?

It's surely upsetting to think about it this way, but when your dog has worms, he's literally being deprived of a good chunk of nutrients he consumes. Worms are ultimately stealing the food that your dog needs in order to be healthy.

To make matters worse, several worms are "zoonotic," meaning that they can be passed from dogs to humans.

Since humans are not the usual host, this can sometimes lead to problematic complications that are fortunately rare, but scary consequences nonetheless.

While there can be several signs of worms in dogs, it's important to consider that not all dogs will display these signs and that your best bet is to have your dog undergo routine fecal tests and regular deworming schedules so as to ensure he is parasite-free and healthy.

Not all dogs show signs of worms


12 Signs Your Dog Has Worms

The most common intestinal worms affecting dogs are hookworms, roundworms, tapeworms, and whipworms. Heartworms are different because they establish themselves in a dog's heart rather than the intestinal tract.

As mentioned, not always worms cause noticeable symptoms in dogs.

Therefore, it is important to have your dog regularly checked for worms and undergo routine deworming schedules as often as your vet recommends.

How to tell if a dog has worms? Following are 12 common signs.

1. Vomiting

When worms reside in the dog's digestive tract, they can trigger irritation and inflammation, leading to bouts of vomiting.

This is more likely to be seen in the case of worms that attach to the dog's intestinal wall as it happens with roundworms.

In heavy infestations, it is possible to occasionally see long, spaghetti-looking worms in the dog's vomit.

In severe cases, roundworms may multiply quickly and even cause an intussusception (a portion of the intestine folding like a telescope) or partial obstruction in the dog's intestinal tract, which can cause dogs to vomit.

If your dog is vomiting, it's important to have him see a vet for proper diagnosis and treatment. Persistent vomiting in dogs may lead to potential dehydration and weight loss.

2. Diarrhea

Worms can cause dogs to develop diarrhea as well.

As with vomiting, worms may irritate the lining of the dog's intestines and may interfere with the dog's digestive process.

Puppies with hookworms may present with bloody red diarrhea, or melena, the presence of tar-like, dark stools made up of digested blood.

3. Abdominal Pain

When worms are present in large amounts, they can take up a lot of space and cause pressure which can lead to belly pain and discomfort.

Worms that attach to the lining of the dog's intestinal wall may also cause significant irritation and inflammation, which can trigger discomfort and pain as well.

4. Dehydration

As dogs with worms develop vomiting and/or diarrhea, they can become dehydrated as a result, especially young puppies.

Young puppies who are weakened by worms may also develop a loss of appetite and may drink less as a result, which makes them more prone to dehydration.

5. Presence of Worms in Dog Stools

Some worms can be visually identified in a dog's stool. The most commonly seen parasites include roundworms and tapeworms.

Roundworms appear like long spaghetti in the dog's stool, while the presence of tapeworm segments may appear like little grains of rice.

It's important to consider that just because you don't visibly see worms, doesn't necessarily mean they're not there!

Even when you submit a fecal sample to your vet, just because no eggs are seen under a microscope, doesn't mean your dog doesn't have worms. It just means that no evidence of eggs was found.

Depending on what life stage the worms are in, they may not be actively shedding eggs at the moment, despite the test coming back "negative."

When I was working for the vet, to avoid confusing clients when we called them with fecal test results, we had to clearly say, "No presence of worms was found at this time."

6. A Pot Belly Appearance

A pot belly appearance is often seen in puppies as a result of worm infestations.

The fact that puppies are still developing and their immune systems are weak makes them particularly predisposed to developing complications from worms.

The irritation and inflammation worms cause to a puppy's digestive tract can lead to bloating.

7. A Dull Coat

Worms in dogs may cause a dull coat for the simple fact that they rob dogs of essential nutrients. With less nutrients available, a dog's coat is destined to become dull, brittle and lacking the typical luster seen in healthy dogs.

Nutrients that help dogs maintain a healthy coat include protein, vitamins, minerals and fatty acids.

Worm infestations compete for these nutrients leading to dogs who are malnourished and develop poor coat conditions.

8. Scooting

Not all worms cause scooting in dogs, but one worm in particular does. The canine tapeworm releases little segments that look like rice that are filled with eggs.

These egg packets routinely detach from the worm and exit the dog's body through the anus. When they crawl out of the anus, they cause an itchy sensation that may cause dogs to scoot.

It's important to note that scooting in dogs may also be triggered by other health issues, such as anal gland problems and localized skin irritations or rashes.

9. Coughing

Coughing may seem like an odd symptom, but it can be seen with some specific worms.

Heartworms are particularly known for causing coughing and breathing problems in affected dogs since these worms live inside the dog's heart, where they can cause major complications.

Coughing may also be seen in the case of hookworms, when they migrate to the dog's trachea, triggering a bout of coughing and swallowing, which sends them to the intestinal tract, explains veterinarian Dr. Ernest Ward.

10. Lack of Energy

Worms can trigger a lack of energy in dogs due to the fact that worms deprive dogs of important nutrients. Malnutrition in dogs is a known cause of lethargy, lack of energy, decreased activity and weakness.

A dog's immune system is also fighting the associated inflammation that worms are known to cause, which can further weaken dogs due to the increased energy demands.

The lack of energy can also be due to the way worms impact the dog's body.

Heartworms are known to cause fatigue and deep exercise intolerance in dogs due to the heavy burden of worms invading their heart and lungs.

Hookworms, on the other hand, can lead to weakness due to the fact that these little vampires attach to the dog's intestinal wall and feast on the dog's blood.

11. Anemia

A variety of worms can cause dogs to develop anemia. Anemia is the medical term used to depict decreased numbers of red blood cells and is often seen with blood loss.

As mentioned, hookworms can trigger anemia in dogs due to the fact that these worms feed on the dog's blood.

Whipworms and roundworms, unlike hookworms, do not feed on the dog's blood directly, but they are known for causing inflammation and damage to the dog's intestinal lining, leading to blood loss.

Severe heartworm disease in dogs can also cause anemia in dogs because the parasite's movements can cause trauma to the dog's red blood cells and vascular walls.

12. Weight Loss

Dogs with worms can develop weight loss, which, once again, is because worms deprive dogs of important nutrients.

On top of this, when dogs have worms, they can cause significant irritation and inflammation, which can lead to loss of appetite, vomiting and diarrhea, and, in turn, cause further loss of nutrients.

If you suspect your dog has worms, please take him to the vet

The 5 Most Common Worms in Dogs

The following are the most common types of worms seen in dogs. Of course, their prevalence will vary based on various factors such as climate, geography, presence of host animals and more.

1. Roundworms

In dogs, the most common species of roundworms is Toxocara canis, although Toxascaris leonina can also affect dogs.

Young puppies with heavy burdens are the most likely to manifest signs of illness such as vomiting, diarrhea, a pot belly appearance, dehydration and abdominal pain.

If the worms happen to migrate to the puppy's lungs, they may even trigger life-threatening pneumonia.

It is possible to see these worms in a dog's vomit and feces. They are an off-white, cream color, typically long and thin, with a spaghetti-like appearance. They can range in size anywhere from two to eight inches in length.

2. Hookworms

The most common species to impact dogs is Ancylostoma caninum.

Affected puppies may show signs of infestation, such as vomiting, bloody diarrhea or melena, lethargy, dehydration, failure to gain weight, and even anemia.

This condition may produce similar symptoms to canine parvovirus in young puppies, and therefore, this possibility should be excluded.

3. Whipworms

The species involved is Trichuris vulpis, also known as canine whipworm.

Affected dogs develop acute or chronic large intestinal diarrhea with the presence of blood and mucus, abdominal pain, loss of appetite and weight loss.

Anemia and other abnormalities may be found on blood tests.

Because adult whipworms produce eggs only intermittently, the absence of eggs in a fecal sample doesn't mean they're not present.

4. Tapeworms

There are several species that affect dogs, but the most common is Dipylidium caninum.

In several cases, dogs do not manifest signs, but heavy burdens may lead to diarrhea, weight loss, and poor growth in developing puppies.

While you cannot see the actual tapeworm, you can find several segments with eggs (proglottids) on your dog's feces or around the anus, and they resemble small grains of rice.

5. Heartworms

Heartworm disease in dogs is caused by Dirofilaria immitis.

Canine heartworms take residence in the dog's pulmonary artery and even in the right ventricle and atrium in the case of severe infestations.

Symptoms dogs may develop include exercise intolerance, coughing and trouble breathing.

Puppies can "inherit" worms from their mothers

6 Ways Dogs Get Worms

With all these unpleasant consequences associated with worms, it makes sense to want to take as many steps as possible to prevent your dogs from getting them. Here are several ways dogs get worms, so you can take further steps to avoid your dog from contracting them.

1. Through the Placenta

Puppies can become infected with worms even before they are born. This happens when their mother has worms, and the worms migrate from her intestinal tract to the placenta, causing the puppies to become infected.

This is known as transplacental transmission. Luckily, this unfortunate circumstance can be prevented by having the mother dog tested and treated for worms before being bred.

2. Ingestion of Infected Milk

Young puppies may also develop worms as a result of nursing from an infected mother.

What happens here is that larvae migrate to the mother's mammary glands and milk ducts, and when puppies nurse, they ingest the larvae, which end up being transferred to the puppy's intestinal tract, where they establish and develop into adults.

3. Ingestion of Eggs or Larvae

Eggs or larvae of several parasites are found in the soil. Basically, what happens is that every time a worm-infested dog poops on the soil, eggs are deposited in the soil.

It may take some time for the eggs to hatch, depending on the type of worm, the weather and other environmental conditions. This can vary from a few days to months.

Once hatched into larvae, these can survive for months to years, and any dog who ingests contaminated feces and soil or licks his feet after walking on the soil can become infected.

This is why it's so fundamental to pick up dog poop promptly.

4. Ingestion of Infected Animals

Dogs may sometimes hunt and eat animals when they are left alone and unsupervised in the yard, or they may scavenge on some dead animals when exploring on walks.

Some animals that may harbor worm larvae and eggs include infected rats, mice, and even infected fleas (in the case of tapeworms).

5. Direct Contact With Skin

In the case of hookworms, dogs get infected by walking on soil that is contaminated with infective hookworm larvae that have hatched from eggs.

Once ingested, the larvae travel to the dog's intestinal tract, where they "hook" to the dog's intestinal wall and feed on the dog's blood.

6. Through a Bite

In this case, we're talking about heartworms. Dogs get heartworm disease after receiving a bite from an infected mosquito which injects infective larvae into the dog's bloodstream.

The larvae travel to the dog's heart and lungs, where they develop into adult heartworms over the course of several months.

Itchiness and scooting can be a sign of tapeworms in dogs

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How Are Dogs Tested for Worms?

Dogs can be easily tested for worms by submitting a fecal sample to the veterinarian. The fecal sample needs to be fresh and doesn't need to be large (just the size of a half-dollar will suffice).

Vet staff will then run a fecal flotation test where a solution separates the ova (parasite eggs) from the feces, and the eggs are then looked at under a microscope for identification purposes.

How Are Dogs Treated for Worms?

If worm eggs are found, the veterinarian will prescribe the most appropriate dewormer. Some broad spectrum dewormers are designed to kill a variety of worms.

Can Humans Get Worms From Dogs?

Yes, certain species of worms can be transmitted to humans, and these are referred to as "zoonotic parasites."

In particular, humans can get infected with roundworms, hookworms and tapeworms, and there may be different ways of transmission.

For instance, roundworms can be contracted by coming into contact with contaminated dog feces or soil. Children are particularly vulnerable since they may touch the dirt and then their mouths without washing their hands first.

Hookworms may be transmitted by walking barefoot on contaminated soils. This is one of the many reasons why dogs aren't allowed on beaches.

Humans may also get tapeworms by accidentally ingesting an infected flea.

Therefore, it's paramount to practice good hygiene by removing poop as soon as possible from yards, washing hands regularly, avoiding contact with dog feces and having dogs regularly tested and dewormed. Good flea population control is also important.


  • A.B. Madril, E.G. Silva, C.C. Alves, A. L. Vasconcellos, E. P. Sousa, P. P. C. CostaPerfil hematológico de cães infectados por Dirofilaria immitis: UNIPAMPA, Bagé, 2020
  • Bendas, A. J. R., Alberigi, B., Galardo, S., Labarthe, N., & Mendes-de-Almeida, F. (2022). Clinical and blood count findings in dogs naturally infected with Dirofilaria immitis . Brazilian Journal of Veterinary Medicine, 44
  • VCA Animal Hospital: Hookworm Infection in Dogs
  • Laboratory Animal Medicine (Third Edition) American College of Laboratory Animal Medicine2015, Pages 511-554

This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.

© 2023 Adrienne Farricelli

(Excluding for the Headline, this article ("story") has not been edited by MiBiz News and is published from a web feed or sourced from the Internet.)