Four Common Intestinal Worms in Dogs

Intestinal worms are parasitic organisms that live in your dog’s digestive system feeding off the dog’s blood and other nutrients.

These worms are passed from dog to dogs or other pets through infected feces that contaminate food, water, soil, or grass that your dog then chews. But dogs can also pick intestinal worms from contaminated fur and paws when they lick them. 

Also, some intestinal parasites require an intermediary host to spread from dog to dog, as in the case of the flea in tapeworm infections.

Because intestinal parasites are a common health issue in dogs, deworming treatments are part of the preventative measures recommended to dog owners as a continuous dog care routine. 

Even then, intestinal worms are a common health issue in dogs. According to a recent DOGPARCS study, intestinal parasites were found in 85% of dog parks and 20% of dogs in the USA.

Puppies are more at risk of getting intestinal worms and developing related health problems like anemia and delayed growth. But adult dogs also get intestinal worms, with most dogs recording worm infection at least once in their lifetime. Adult dogs with weak immune systems are most at risk of worm infection and manifest adverse intestinal parasitism with severe clinical signs.

Several intestinal worms can infect your dog. However, four of these are the most common intestinal worms in dogs:

• Roundworms
• Hookworms
• Tapeworms
• Whipworms 

This article is a Complete Dog Owner’s Guide to Understanding Common Intestinal Worms in Dogs. Here you’ll find everything you need to know about the nature, symptoms, diagnosis, treatment, and prevention of roundworms, hookworms, tapeworms, and whipworms. 

Roundworms in Dogs

Roundworms are the most prevalent of the four common intestinal parasites. While this is explained by the simple way roundworm larvae are passed from dogs and other animals to other dogs, their fast-spreading trend is also defined by their high reproduction rate. 

According to the Companion Animal Parasite Council (CAPC), common roundworm species in dogs can produce up to 200,000 microscopic eggs in a day.

But what exactly are roundworms, and how does your dog get infected with the parasites?

What are Roundworms?

Roundworms are parasites that live in your dog’s intestines feeding on partially digested food. These parasites are also known as nematodes or ascarids. 

There are several roundworms species, but two of these are more common in dogs:

• Toxocara canis
• Toxascaris leonina

Toxacara canis causes severe disease in dogs and is more aggressive in its spread. In fact, past surveys have shown that around 30% of puppies below the age of 6 months are shed Toxocara canis eggs across all the states in the US. Also, Toxacara canis is zoonotic and can be transmitted to humans. 

What Do Roundworms Look Like?

It is possible to see roundworms in dog feces or vomit with your naked eye. The worms have a tubular, round shape, which is why they are called roundworms.

Roundworms present in a light brown or whitish color and can grow up to several inches, mimicking the appearance of boiled spaghetti. 

Note that not noticing roundworms in your dog’s poop does not mean your pet is free of nematodes. As such, it is always best to bring your dog for scheduled worm tests to confirm that he is truly free of the parasites and their eggs.

How do Dog Get Roundworms?

Dogs can be infected with roundworms through a number of transmission modes:

Mother to puppy transmission

Larvae in a dog’s intestines move to different body tissues and hibernate as dormant cysts. In female dogs, hibernating roundworm larvae become active during estrus (period of heat and fertility). During pregnancy, they move through the placenta to the fetus. In other dogs, periods of low immune system activate hibernating roundworm larva.

Nursing dogs also pass roundworm larvae to their puppies through breast milk. 

Through contact with contaminated feces

Infected dogs and pets shed roundworm eggs in their feces. Healthy dogs can lick the feces, eat or drink food contaminated with the infected feces, or eat soil or grass infected with roundworm eggs from other dog feces.

Ingesting roundworm eggs in host animals

Your dog can swallow roundworms eggs by eating animals that act as paratenic hosts for roundworm eggs. These could be rodents, birds, cockroaches, or earthworms. Roundworm eggs can survive for some time in these hosts but do not mature inside them.

The Roundworm Lifecycle

Roundworms have a complex lifecycle, as shown in the diagramed stages:

Symptoms of Roundworms in Dogs

Dogs with roundworms may not show clinical signs immediately. Also, some of the roundworms symptoms may be more obvious to the dog owner, while others need the eye and expertise of a veterinarian.

How are Roundworm in Dogs Diagnosed?

While the signs listed above can be a clear first indication that your dog is infected with roundworms, a more definitive diagnosis is done by a vet through the microscopic examination of the feces known as fecal floatation. 

Fecal floatation entails mixing a tiny amount of the dog’s feces with a solution that makes the roundworm eggs float. These eggs are then placed with a glass slide under a microscope for closer examination.

How to Treat Roundworms in Dogs

The treatment of roundworms is straightforward and involves giving your dog deworming drugs. Your dog’s vet will advise you on the best treatment option for your dog. The choice could be from one of the following deworming drugs: 

Three first doses of these drugs are given to kill adult worms. Subsequently, the vet will give follow-up doses to eliminate new roundworms that were not mature when the first doses were given. 

In 2020, the FDA also approved Simparica Trio (Sarolaner, Moxidectin, & Pyrantel) with indications for the treatment and control of roundworms and hookworms, as well as heartworms, fleas, and ticks.

Note that there are no home remedies for roundworms in dogs. Your dog has to be seen by a vet for roundworm diagnosis and treatment. However, you can do a lot at home to prevent roundworms in dogs, as we explain below.

Prevention of Roundworms in Dogs

Because they produce hundreds of thousands of eggs every day, roundworms spread quickly and can be elusive to control and prevent. 

Nonetheless, roundworms in dogs can be prevented in the following ways:

• Regularly giving your dog routine roundworm preventative drugs. Puppies should be started on roundworm deworming meds at 3 weeks of age and repeated every few weeks during puppyhood.
• Exercising high levels of hygiene for both you and your dog, especially with feeding bowls, play toys, and sleeping areas, and washing your hands always after handling your pet.
• Collecting and properly disposing of dog poop to halt the roundworm infection cycle.
• Keeping your dog on a leash during walks and in a fenced yard while outside the home. This prevents your dog from hunting and eating roundworm larvae carrier-animals like birds and rodents.
• If your dog is pregnant, talking to her vet about proper deworming to preempt the passage of roundworms from mother to puppy.
• Bringing your puppy for stool examination 2-4 times in the first year and 1-2 times each year for adult dogs.

Can Humans get Roundworms from Dogs?

Yes. If humans interact with the larvae of roundworms through their pets or by eating fruit and vegetables contaminated by infected soil, they can end up swallowing the larvae. The larvae then invade tissues and are encysted in body organs.

However, humans act like other roundworms paratenic (accidental) hosts with no symptoms except in the following cases:  

• If roundworm larvae migrate, they can cause Visceral Larval Migrans, a liver problem that causes fever and liver enlargement. 
• If children ingest large numbers of roundworm eggs, they can develop clinical disease and show roundworm symptoms.
• In rare cases, roundworm larvae can also move to the eyes, causing Ocular Larval Migrans or visual impairment with potential blindness.  

From the preceding, humans should observe high-level hygiene when handling their pets and clean fruits and vegetables thoroughly.

Also, because of the health risks that roundworms pose to humans, the CDC recommends deworming dogs every month.

Hookworms in Dogs

Hookworms are a common parasite of dogs globally and in the United States. They are reported in all states of the US but are most common in tropical and semitropical climates along the East coast. The 2020 DOGPARCS study mentioned earlier found a 7.1% hookworm prevalence in dogs. 

But what are hookworms, and what do they do to your dog? Keep reading to answer all your dog hookworm questions.

What are Hookworms?

Hookworms are parasitic intestinal worms that survive in your dog’s digestive system by attaching themselves to the intestinal wall and living on your dog’s blood. They produce eggs that are ejected from your dog’s digestive system with the feces, spreading the infection to other dogs and animals.

There are 3 main species of Hookworms:

• Ancylostoma caninum
• Ancylostoma braziliense
• Uncinaria stenocephala

In dogs, A. caninum is the most common type of hookworm and causes severe disease. A. braziliense and U. stenocephala are more limited in their geographical spread and effects on dogs.

Can you See Hookworms in Dog Poop? How Do Hookworms Look Like?

Hookworms are tiny worms, around 2-3mm long. Even though they are passed in your dog’s stool, it’s impossible to see them with your naked eyes. 

Seen on a microscope, hookworms manifest hook-like mouth parts, which is the feature that gives them their name. The mouthpiece also serves to hook the worms on your dog’s intestinal lining.

How are Hookworms in Dogs Transmitted?

Your dog can get hookworms through one of these modes of transmission:

• Orally – by swallowing hookworm larvae from soil contaminated by the feces of infected dogs, licking dirty feet while grooming, or sniffing contaminated feces or soil.
• Through the skin – when the dog comes into contact with hookworm larvae in the environment and the larvae penetrate the skin.
• In-utero transmission – from mother to puppy through the placenta before birth. 
• Transmammary transmission – through the mother’s milk during nursing.

Dog Hookworm Lifecycle

The lifecycle of the hookworm is a lot similar to that of the roundworm: 

In the first stage, female hookworms in a dog’s digestive system pass hundreds of eggs. These eggs are passed into the environment through the dog’s feces. Hookworm larvae then hatch from the eggs and survive in the soil for months.

In the second stage of the hookworm cycle, dogs will pick the larvae from the environment by swallowing or sniffing them from the soil. Ingested hookworm larvae move to the intestinal tract. Some larvae may also end up on the trachea and are coughed up and swallowed. 

Alternatively, hookworm larvae get into your dog’s body through the skin and then migrate into the trachea or lungs. They are later coughed up, swallowed, and sent into the intestinal tract. The larva may also lie dormant in other muscles and body tissues. 

Hookworm larvae get into the puppies’ intestinal tract through their mothers’ milk or the placenta during gestation.

In the third stage, hookworm larvae become active due to pregnancy, stress, or a compromised immune system. The larvae develop into mature hookworms and live on your dog’s blood, consequently shedding eggs and reinitiating the cycle when the eggs are injected into the environment with your dog’s feces.

How will Hookworms Affect my Dog?

Adult hookworms attached to your dog’s intestines are heavy blood-suckers as they solely live on your dog’s blood. As a result, they are a health threat to your pet, especially young puppies. 

Puppies with hookworms can easily suffer from anemia (low red blood cell count) and weight loss. In extreme cases, the puppy may need a blood transfusion. Though less common, adult dogs with hookworms may also suffer chronic anemia. Severe anemia can be fatal.

Because they inject an anti-coagulant fluid when they hook and feed on your dog’s blood and intestinal fluid, hookworms can cause intestinal bleeding. That will make your dog’s blood not clot, and once the worms detach, the intestines keep bleeding. Large numbers of hookworms in a dog’s intestines can cause inflammation. 

Apart from these adverse effects on your dog, hookworm infection manifests in several other symptoms discussed in the next section.

Symptoms of Hookworms in Dogs

Symptoms of hookworms can vary in severity depending on whether the worms are in a puppy or an adult dog and the stage of the hookworms.

Hookworm infection causes intestinal distress for both puppies and dogs and can trigger skin irritation if the larvae migrate to the skin, especially to the toes. 

Some adult dogs may become hookworm carriers with no apparent symptoms but still keep shedding eggs into the environment. 

How are Hookworms in Dogs Diagnosed?

While the clinical signs can signal hookworm infection, these signs are similar to other intestinal worm infections. As such, the most conclusive mode for diagnosing hookworms in dogs is fecal flotation with centrifugation.

This involves mixing a dog’s stool with floatation solutions in a container known as a centrifuge so that more force is exacted to make the hookworm float.

Hookworms may also be diagnosed through fecal antigen tests. These tests assess a dog’s stool for young and mature hookworm proteins. This method is especially useful in single-sex hookworm infections where no eggs are produced.

How are Hookworms in Dogs Treated?

There’s a wide range of topical and oral medications approved for the control and treatment of hookworms, as shown in the table.

Intervention Type	Treatment
Routine Dewormers	– Fenbendazole – Milbemycin oxime – Pyrantel pamoate – Moxidectin Note: These do not kill third-stage larvae in body tissues.
Hookworm Treatment	– Advantage Multi® (imidacloprid + moxidectin)  – Coraxis (moxidectin) – Drontal® (praziquantel/pyrantel pamoate/febantel) – Heartgard® (ivermectin/pyrantel) – HeartShield™ (ivermectin/pyrantel) – Interceptor® (milbemycin oxime) – Iverhart Max® (ivermectin/pyrantel/praziquantel) – Iverhart Plus® (ivermectin/pyrantel) – PetTrust™ (ivermectin/pyrantel) – Panacur® (fenbendazole) – ProHeart® 6 (moxidectin) – ProHeart® 12 (moxidectin) – Tri-Heart® (ivermectin/pyrantel) – Sentinel® (milbemycin oxime/lufenuron) – Trifexis® (milbemycin oxime/spinosad)

Note: The meds may be prescribed for different hookworm species, so always work with your dog’s vet.

In severe cases, supportive treatment may be required in the form of:

• Electrolyte and fluid therapy for puppies with severe anemia.
• Iron supplements.
• A high-protein diet.
• Blood transfusions in severe anemia.

Note that recent studies have shown widespread resistance to hookworm medication among dogs. For example, a 2021 study that used Moxidectin, Albendazole, and a combination of Febantel, Pyrantel, & Moxidectin confirmed multiple drug resistance among Greyhounds in the US. This reaffirms the need to always work with your dog’s vet for the best results.

Can Hookworms in Dogs be Prevented?

Hookworms in dogs can be prevented, and the best preventive measure is the use of hookworm preventative dewormers. 

Because they have a high risk of hookworm infection, puppies should be started on hookworm prevention meds by week 2 and repeated in weeks 4, 6, and 8. Hookworm dewormers should then be given every month after that. In addition, fecal tests should be done at least 4 times a year, then twice every year.

Adult dogs should be tested regularly for hookworms and be on monthly hookworm preventive drugs.

The following additional preventive measures should also be taken:

• Keeping high levels of hygiene, so your dog is not exposed to infected soil or feeding bowls.
• Collecting and appropriately disposing of dog feces to stop the roundworm infection cycle.
• Faithfully deworming pregnant dogs, so hookworm larvae are not passed to puppies during gestation or after birth.

Can People get Hookworms from Dogs?

Yes. Hookworms are zoonotic, which means humans can get infected by interacting with dogs that have hookworm larvae on their skin, with contaminated soil, or by eating vegetables or fruits contaminated with feces from infected dogs. Walking barefoot on contaminated sand beaches can equally cause infection.

Usually, hookworm larvae burrow in human skin, causing cutaneous larval migrans, an excessively itchy lesion.

Dog hookworm larvae can also migrate into human lungs and the small intestines. In human intestines, hookworms cause enteritis (inflammation of the small intestines) and abdominal pain. This is why preventative hygiene is geared towards protecting both dogs and humans.

Tapeworms in Dogs

Tapeworms are less common intestinal parasites than roundworms, whipworms, and tapeworms. A remote study found that tapeworms had a 2.2% prevalence among dogs in Louisiana compared to 38.5%, 4.9%, and 8.5% prevalence of hookworms, whipworms, and roundworms respectively.

Also, tapeworm infection in dogs is associated with less severe disease, but that does not imply the intestinal parasites should be left to dwell in your dog.

What are Tapeworms?

Tapeworms are intestinal parasites presenting in a flat and segmented form. Adult tapeworms can grow up to 30cm (11 inches) in length. As they mature, segments of tapeworms known as proglottids detach from the worm and are passed in dog feces. A proglottid can be around 12mm (half an inch) long and mimic a grain of rice or a cucumber seed.

Proglottids carry around 20 tapeworm eggs. Once deposited in the environment, they dry up and turn golden and eventually break open. When breaking open eggs are released to the environment. 

While there are more than a single type of tapeworm, the Dipylidium caninum species is the most common in dogs. Others include Taenia, Echinococcus, and Metacestoides

How does a Dog Get Tapeworms? / The Tapeworm Lifecycle

Tapeworms have an indirect life cycle, with fleas (and in rare cases lice) as intermediate hosts. That means your dog cannot get infected with tapeworms from other dogs. Instead your dog must ingest a flea that is a host for flea larvae.

The tapeworm lifecycle looks something like what’s shown on the diagram.

What are the Symptoms of Tapeworms in Dogs?

Tapeworm infection in dogs does not show a wide range of symptoms. However, your dog will still show all or some of these tapeworm symptoms:

How do I Know My Dog has Tapeworms?

Tapeworm diagnosis in dogs relies on the presence of proglottids in your dog’s feces. Although fecal floatation can be done, the lack of uniform proglottid distribution in your dog’s waste cannot be relied on. Besides, tapeworm eggs do not float consistently.

As such, your dog’s vet will rely on your information about the presence of tapeworm segments in your dog’s waste to diagnose the pet for tapeworms.

Tapeworm Treatment in Dogs

The treatment of dog tapeworms is effectively done with Praziquantel and Epsiprantel. Praziquantel causes tapeworms attached to your dog’s intestines to detach. They are then digested as they pass through the dog’s gut.

Some tapeworm infections may show resistance to both Praziquantel and Epsiprantel. In these cases, Nitazoxanide is used off-label (as a med that’s not listed for dog tapeworm treatment).

It is important that treatment for tapeworms is combined with effective flea control to prevent re-infection.

Control and Prevention of Dog Tapeworms

There are two primary ways of controlling and preventing tapeworms in dogs:

Are there Effective Home Remedies for Tapeworms in Dogs?

There are no verified home remedies for tapeworms in dogs. Even so, you may hear claims that some natural remedies are effective in preventing and treating dog tapeworms. Often these include:

• Apple cider vinegar – makes a dog’s gut environment unfavorable for tapeworms to thrive.
• Garlic – also makes a dog’s gut environment unfavorable for tapeworms to thrive.
• Turmeric – considered a gut-healing remedy from the inflammation caused by tapeworms.
• Pumpkin seeds – remove the attached tapeworms from the intestinal lining, making them pass through the digestive system and out with the feces.

Before thinking of using a home remedy for tapeworm treatment, you should talk to your dog’s vet about it.

Home remedies are not really needed for the prevention and treatment of tapeworms in our opinion. Tapeworm meds are cheap and generally effective.

Can I Get Tapeworms from my Dog?

Tapeworm transmission from dogs to humans is extremely rare. It would require you to ingest a flea that hosts infective tapeworm larvae.

The known rare cases of children getting tapeworms have been associated with poor hygiene. Which is a good reason why washing your hands after handling your dog is a good idea.

Whipworms in Dogs

Whipworms (Trichuris vulpis) are a global occurrence in dogs but less common than hookworms and roundworms. In the US, Whipworm prevalence has shown a fluctuating trend over the years. 

For example, a longitudinal study from 2012-2018 showed that annual whipworm prevalence among dogs in the US decreased from 0.83% to 0.67% in 2018. By 2020, however, info from the Companion Animal Parasite Council indicated a 14.3% whipworm prevalence among shelter dogs and a 10% prevalence among dogs attended to in veterinary teaching hospitals.

Among the four most common intestinal worms in dogs, whipworms cause the most severe disease. But what exactly are whipworms, and how are dogs diagnosed and treated for whipworm infection? We’ll address that and more in the following sections.

What are Whipworms?

Whipworms are parasitic intestinal worms growing to about 6mm (1/4 inch) and mimicking the shape of a whip, which is why they are called whipworms.

The worms live in the colon and cecum (the part at the beginning of the large intestines). They use their ‘whip’ to cause damage by slashing and shredding the intestinal lining tissue. Whipworms feed on the damaged lining and suck blood, causing severe irritation to your dog.

Whipworm Transmission and Lifecycle

A dog is infected with whipworms by ingesting infective eggs from the soil or other substances contaminated by infected dog feces. This is the only mode of whipworm transmission with no intermediary whipworm egg hosts. 

That makes the whipworm lifecycle quite simple, consisting of 5 quick stages:

Stage	Explanation
First	Adult whipworms in infected dogs lay eggs that are deposited into the environment through a dog’s feces.
Second	Whipworm eggs mature to the infective stage in the feces and can survive in the soil for years.
Third	Mature whipworm eggs are ingested by other dogs.
Fourth	Ingested infective whipworm eggs hatch and develop into adult whipworms in the lower intestinal tract.
Fifth	Adult whipworms begin to lay eggs by 2.5-3 months, which are then expelled with the feces to continue the whipworm infection cycle.

What are the Symptoms of Whipworms in Dogs?

In dogs, mild whipworm infection is usually asymptomatic or can present with signs similar to those of the large intestines inflammation.

Note that whipworm infection symptoms begin to show way before whipworm eggs are seen in the dog’s stool during lab microscopic examination. 

It’s also important to note that untreated severe whipworm infection in dogs can turn fatal.

How is Whipworm Infection in Dogs Diagnosed?

Whipworm infection is clinically tested using fecal floatation and centrifugation. However, this method is often unreliable because whipworms shed few eggs on a sporadic basis. 

Also, a female whipworm only starts to lay eggs approximately 3 months after hatching. As a result, dogs with whipworm infection can return a negative test when the dog is actually infected. 

Because of this, veterinarians will often treat dogs for whipworms based on the visible clinical signs listed above. 

In recent years, whipworm infection has been detected using the enzyme-linked immunosorbent assay (ELISA) test. In 2014, IDEXX Laboratories introduced the first ELISA test that can detect the presence of adult whipworm proteins in dog feces. This is a more reliable test than the fecal floatation procedure.

Whipworm in Dogs Treatment? 

There are two primary drugs approved for the treatment of whipworm infection in dogs:

• Drontal Plus® (Febantel, Pyrantel pamoate, & Praziquantel) – administered as a single dose. 
• Panacur® (Fenbendazole) – administered for 3 consecutive days.

These two drugs can be administered once a month for 3 months to achieve the best results in your dog’s whipworm treatment.

The following meds are also approved for both treatment and the monthly prevention of whipworms in dogs: 

• Advantage Multi (Moxidectin & Imidacloprid).
• Interceptor® (Milbemycin oxime).
• Interceptor® Plus (Milbemycin oxime & Praziquantel). 
• Trifexis® (Milbemycin oxime & Spinosad).
• Sentinel (Milbemycin oxime & Lufenuron).
• Sentinel Spectrum (Milbemycin oxime, Lufenuron, & Praziquantel).
• Coraxis™ (Moxidectin).

How are Whipworms in Dogs Prevented?

Maintaining high hygienic standards in your dog’s living area is a primary and inexpensive way of preventing whipworms in dogs.

In addition, you should administer one of the whipworm preventatives listed above. Preventative whipworm meds should especially be given to dogs in areas where whipworms are most common. See the Companion Animal Parasite Council whipworm prevalence maps.

Also, your dog’s vet can advise you to use heartworm preventative drugs that have active ingredients for whipworm infections or a combination of those ingredients. These can be:

As a precaution, always work with your dog’s vet to determine which whipworm treatment or prevention drug is best for your dog.

Can Humans get Whipworms from Dogs?

No. Whipworms of the Trichuris vulpis species are exclusive parasites of dogs and are not infectious to people. 

However, Trichuris trichiura is a human whipworm species spread through the ingestion of whipworm eggs from contaminated human feces. According to the CDC, Trichuris trichiura is the third most common intestinal parasite in humans.