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There are a variety of worms that can affect dogs. They differ, for example, in their size and shape. Some are only a few millimeters long, while others can reach a length of up to 70 cm. A worm treatment in dogs does not have a preventive effect but kills the parasites in the intestine if it is used in time. For a better overview, the most well-known worms in dogs are listed.

These Worms Can Affect Dogs! 3

Cucumber seed tapeworms

Cucumber seed tapeworms are one of the most common tapeworms. The parasites occur worldwide and use fleas as intermediate hosts. If the dog suffers from flea infestation, there is an increased risk. When grooming their fur, the four-legged friend can swallow the larvae of the cucumber tapeworm. In the dog’s intestine, the larvae then grow to a size of 10-70 cm into adult tapeworms.

In the case of massive infestation or in weakened dogs, loss of appetite, diarrhea, or cramps in the intestines may appear.

Fox tapeworms

As the name suggests, this parasite is predominantly found in the red fox. But dogs and cats are also affected in this country. The eggs of the fox tapeworms are excreted with the feces. Rodents, such as mice or rats, serve as intermediate hosts for the parasite. Hunting and free-running dogs are particularly at risk of becoming infected with the fox tapeworm: If a dog eats an infected rodent, the parasite gets into the dog.

Fox tapeworms are very tiny with a length of 2 – 4 mm.


The hookworms are small parasites (approx. 3 – 4 cm) with serious health risks: This type of worm soaks up the blood of its host. Therefore, a high infestation leads to dangerous blood loss.

The hookworm larvae penetrate the dog through the skin. But eating larvae can also lead to infection. This happens when the dog eats an infected dog’s feces or infested grass, for example. This type of parasite occurs mainly in southern and eastern Europe.


As the name suggests, the parasite is located in the heart of its host or in its pulmonary arteries. The worm is particularly dangerous because of its size: When fully grown, it can reach a length of up to 30 cm.

The parasites get into the dog mainly through the mosquito. In Europe, they are common in many Mediterranean countries such as Spain, Italy, and Greece. Heartworm infestation can lead to serious health problems. If the number and size of the parasites are considerable, they can only be removed surgically. Therefore, immediate treatment is important.

Dog roundworms

Dog roundworms (Toxocara canis) can reach a size of up to 18 cm and can be found in their host’s intestines. There the females lay their eggs, which the dog in turn excretes. The eggs are very resilient and can survive for a long time. If the dog’s feces are not removed, the eggs can be transmitted to other dogs.

Roundworms are transmitted to puppies when the mother is infected. In the case of massive infestation, the puppies suffer from a bloated stomach. If treatment is delayed and the infestation is severe, the infection can be fatal.


The most common whipworm found worldwide is the “Trichuris vulpis”. It is a colon parasite, which reaches a size of about 4 – 7 cm. Affected dogs suffer from diarrhea. If the whipworm infestation is greater, abdominal pain, vomiting and blood loss appear. In addition, the dogs tend to have a loss of appetite.

The four-legged friends can inter alia. infected by ingesting infected soil or the faeces of other dogs that are infected. The eggs are particularly robust and can survive for a long time.