Worms in dogs And Cats: All You Need to Know About Pet Worms

Worms in dog

Worms are internal parasites and a common problem in dogs and cats. There are different types of worms in dogs like heartworm and lungworm, tapeworm, roundworm (roundworm, hookworm, and whipworm) and the fox tapeworm.

Almost all puppies and kittens are already infected with roundworms while they are still in the womb, or contract the infection through breast milk immediately after birth. In addition, animals of all ages are constantly exposed to potentially harmful parasites via the environment.

For example soil in gardens and parks that are infected with worm eggs or larvae, by prey animals (for example snails and mice) that carry the infection and via mosquito bites, that can transmit a heart / or lungworm infection. Feeding raw meat can also cause worm infection.

The parasites are usually hidden in the intestines or elsewhere in the body, where they are invisible but affect the health of the animal.

Although some of these parasites are very dangerous, they can easily be controlled and disease can be prevented.

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You can have your pet examined for worms. Tapeworms reveal themselves quickly, there are small white pieces (maggots) on the stool of the dog or cat, which when they dry up become a bit browner (grain of rice).

Other worms are much harder to find, the eggs are microscopically small, the larvae are not clearly visible and dead adult worms are usually digested before they leave the body. Stool examination is a simple and inexpensive method for determining worm infections. So you don’t always have to see worms for infection with worms!

Deworming Advice

Worms in puppies and kittens:

How often do cats or dogs need to be dewormed? Since almost all puppies and kittens are already infected at birth or immediately afterward and they are re-infected continuously through breast milk and the environment, it is important to start the deworming in the first weeks of life and to treat them often afterward.

It is best to deworm every two weeks from the moment puppies are 2 weeks old and kittens 4 weeks old, up to the age of 10-12 weeks. Then monthly worming until the puppy/kitten is 6 months old.

Worms in dogs and cats (adult):

In general, adult animals themselves have little trouble with worm infections. They do, however, constitute a source of contamination for other animals and, more importantly, for yourself. Due to the large spread of worms and the ease with which the infection can be contracted, adult dogs and cats also need to be treated 3 to 4 times a year.

For the control of tapeworms, it is also of great importance that the fleas are controlled. These always cause a new infection.

Heart and lungworms can cause serious symptoms and must be adequately controlled, as long as your pet is at risk of infection (eg when traveling).

There are many resources available for the treatment and control of worms. Make sure you give your pet the means that best meets his and your needs in terms of ease of use, effectiveness, safety (especially when treating very young puppies and kittens) and circumstances (such as traveling).

Types of worms


Heartworms are the most life-threatening worms, which mainly occur in the south and east of Europe, but not (yet) in the Netherlands. Adult worms are 10 to 30 cm long and have a diameter of approximately 1 mm.


Infection takes place through the stinging of infected mosquitoes, which causes small larvae to enter the bloodstream. These larvae can grow into adult worms more than 20 cm long, which reside in the heart and pulmonary arteries. Damage to the heart can cause heart failure that can cause the animal to die.

When a mosquito bites an infected dog, it picks up these larvae and can thus pass the infection on to other dogs.


Over time, the presence of adult worms in the heart and pulmonary arteries causes inflammation and thickening of the wall of the veins, leading to an increase in blood pressure and a greater effort of the heart to get blood through these veins. As a result, the dog’s heart function may fail, which may ultimately lead to death.

The dog usually shows clinical symptoms only when the disease has reached a very serious stage. The first signs are occasional coughing and fatigue; later the cough becomes chronic and is accompanied by difficulty breathing, mild anemia, and listlessness. In advanced cases, the dog may even collapse after light physical exertion. Most dogs eventually develop heart failure.


Killing adult worms with worm agents is dangerous. The worm remains can form ‘plugs’ (emboli) that can get stuck in the smaller blood vessels, leading to infarctions.

In contrast to treatment, heartworm prevention is safe, easy and effective and important when traveling with your pet to southern and/or eastern Europe.

Preventive drugs are usually administered monthly during the risk period from April to November if your pet stays in a risk area for a longer period of time. For a holiday shorter than 1 month, your pet must be treated against heartworm after returning home and a month later.


Tapeworms are common parasites in the small intestine of dogs and cats; they are flat and can be from a few millimeters to 2.5 meters long. They attach themselves to the intestinal wall of the animal and live on the intestinal contents that are absorbed through their integument (‘skin’).

The most common complaint they cause is the itching of the anus. This tapeworm can also infect humans, especially children, but is generally not dangerous.


Adult tapeworms live in the intestines where they lay eggs that end up in the environment through the excrement. These eggs contain a larva in the first stage and when they are eaten by an intermediate host, the development continues until the second larval stage.

Examples of intermediate hosts are a small mammal such as a mouse, a ruminant (contaminated raw meat) or an arthropod such as a flea. The larvae are contagious to the dog and cat and when swallowed by the intermediate host or its tissues, they attach to the intestinal wall and mature within a few weeks.

Tapeworm in dog
Tapeworm in dog | avalonvet.com

Tapeworms betray themselves quickly; if your pet has a tapeworm infection you can often see small white pieces the size of a grain of rice around the anus or in the stool. These segments (parts) of the tapeworm contain large amounts of tapeworm eggs.


Fleas play an important role as an intermediate host. When fighting tapeworms, it is therefore also important to take good care of the fleas.


Adult tapeworms are unpleasant to see, but cause little damage to dogs and cats, although serious infections can lead to intestinal damage due to the physical presence of the worms.


Lungworms have recently also been found in the Netherlands, and the risk of infection of your dog or cat is increasing throughout Europe. The French heartworm (Angiostrongylus vasorum) is the most common dog worm.

Lung worm in dogs
Lung worm in dogs | stannesvets.co.uk


A dog becomes infected with lungworm by eating larvae, which can be present in nudibranch and house snails and frogs (intermediate hosts), but also in the ground, in prey animals (who have eaten snails) and the feces of other dogs.

The larvae move into the body of the intestines, via the liver to the heart and lungs, where they nestle as adult worms in the small pulmonary arteries. The worms lay eggs, the young larvae that emerge from it are coughed up, swallowed and end up in the stool.

An infection with lungworm can be determined through fecal examination, using a special method to detect the worm eggs.


An infection with lungworm can lead to breathing problems, such as coughing and tightness, reduced endurance, bleeding and losing weight.

Roundworms / Hookworm

Hookworms are mainly seen in animals in shelters, kennels and stray animals, but can also infect our pets. The hookworm Uncunaria stenocephale is the most common in the Netherlands, infection is mainly caused by licking up contaminated soil or prey, and skin is less common.

Roundworms in dog
Roundworms in dog | wikihow.com

In Southern Europe the hookworm Ancylostoma caninum is more dangerous for the dog, this worm can easily penetrate through the skin and can cause severe intestinal inflammation. In the cat, the hookworm Ancylostoma tubaeforma is mainly seen in stray animals.


Adult hookworms live in the small intestines of dogs and cats, where they lay eggs that end up in the environment through the excrement. Within a few weeks, larvae hatch from the eggs, ready to infect the dog or cat.

After the infection, the larvae start to move through the body (migrate) until they reach their final destination: the intestines, where they develop into adult worms that lay eggs. Some larvae do not reach the gut: they remain encapsulated in different organs until a stimulus, such as pregnancy, reactivates them and causes them to migrate again, end up in the intestines and develop into adult worms.


Larvae that penetrate the skin cause a severe, itchy inflammation; Migration through the respiratory system can lead to inflammation and coughing. Adult worms attach themselves to the intestinal wall with hook-shaped teeth and feed on blood and tissue, which can cause discomfort, bloody diarrhea and even anemia.


Roundworms, also known as Ascaris, are most common in dogs and cats (Toxocara Canis and Toxocara Cati, respectively). The adult worms are located in the small intestine, where they live from the intestinal contents. In appearance they look like spaghetti: they are 2-3 mm thick and up to 20 cm long.


When a dog or cat swallows the worm eggs, they enter the stomach. The larvae then penetrate the stomach wall and move (migrate) to different organs before returning to the intestinal tract and developing into adult worms.

Adult roundworms live in the small intestines of dogs and cats, where they lay up to 80,000 eggs per day. These eggs end up in the environment through the excrement and within a few weeks, an infectious larva develops.

Some larvae do not return to the intestines: they remain encapsulated in the various organs until a stimulus, such as pregnancy, reactivates them and causes them to migrate again and develop into adult worms in the intestines.

Puppies and kittens are infected through breast milk immediately after birth. In addition, dogs and cats can absorb roundworms through the environment, by accidentally swallowing the infectious eggs in contaminated soil or by eating infected rodents.


Roundworms are especially harmful to puppies and kittens, with large numbers they can cause diarrhea, decreased appetite, and retardation of growth. With serious infections, there is a risk of clogging of the intestine.

The journey that the larvae make through the body can cause liver, lung and brain damage.


Whipworms are parasites that often occur in the blind and colon of dogs and cats; they are thin and 5-7 cm long. They are rare, but the infection pressure can be high in kennels with insufficient hygiene measures.


An animal can get whipworms by accidentally swallowing the worm eggs through contaminated soil. The eggs hatch in the dog or cat’s intestines and within 60 to 90 days the larvae develop into adult worms that lay eggs and can live in the intestine for 1.5 years.

Since the eggs are not excreted regularly, diagnosis can be difficult and more than one examination of stool may be required. Whipworms use their mouths as a spear-shaped sword that they use to pierce and pierce the intestinal wall, and they live off the blood and tissue fluids released.

Due to the particularly high resistance of these eggs, it is very difficult to control them in the environment.


Because of their eating habits, whipworms can cause bloody diarrhea, weight loss, anemia, and dehydration, especially in the case of a serious infection. Fortunately, most infections are low and often go without complaints.

Fox tapeworm

The fox tapeworm can be very dangerous, even fatal, for humans. People can become infected by eating forest fruit/mushrooms or through infected dogs. Although dogs do not suffer from this parasite, it is important to treat them preventively because of the risk to humans.


The natural host is the fox, which in case of infection secretes eggs in the stools, which can be absorbed by rodents. Dogs can become infected through contact with fox feces, contaminated soil or prey such as voles. After infection, they also excrete eggs through the feces but do not develop any further symptoms.


Animals that live in areas where the fox tapeworm occurs should be treated monthly with an agent that contains praziquantel or epsiquantel.

How often do I have to worm my dog ​​or cat?

Worming is part of the standard care of your dog or cat. By doing this on a regular basis you can keep your pet in good condition and prevent illness. Some worms are transferable to humans. So fighting worms is not only important for the health of your pet, but also for yourself!

Infection with worms

Worms are parasites that can (survive) in different places in the body of your dog or cat. The most common are roundworms, whipworms, tapeworms, hookworms, lungworms and heartworms. Dogs and cats can be infected with roundworms in different ways: by direct ingestion of eggs or larvae from the environment, by ingestion of prey, via breast milk or directly via the placenta (puppies).


Worms can cause a variety of complaints. This depends on the type of worm infection and how serious the infection is. Sometimes infections run without complaints, this can occur with, for example, tapeworms, tapes, and whipworms. In other cases, vague symptoms may arise such as weight loss, poor condition, dull fur, anal itching or mild intestinal complaints. Hook and whipworms can cause severe intestinal complaints such as (bloody) diarrhea, anemia and/or weight loss.

Treatment against worms
By regularly worming with an effective worm medicine, make sure that the worms that are present in the body die and can no longer produce eggs. There are various means that can be used to prevent your dog or cat from becoming ill from these annoying parasites.

Worming remains important

If these worms or eggs are indeed found in the feces of your dog or cat, it still remains very important to administer an effective worming agent. Worm infection can not only have unpleasant consequences for your dog or cat, but the parasites also pose a health risk to ourselves. It is therefore also important to continue to check this at least four times a year, even more often because it is still a snapshot.

Do you want more information about this subject? Visit the veterinarian near you or let us know by writing in the comment section.


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