Dogs can suffer from various types of worms, each with its own symptoms. In general, worms can weaken a dog's condition, causing vague symptoms such as weight loss, a dull coat, and lethargy. Digestive problems, such as diarrhea, are also often a sign of a worm infection. The treatment varies depending on the type of worm.

Here is an overview of the most common worms found in dogs.

Roundworms (Toxocara canis)

Roundworms are among the most common intestinal worms in dogs. They live in the small intestine and feed on the food contents. Dogs can become infected by ingesting worm eggs, for example, by sniffing contaminated soil or feces. These worms can grow very large and are found in about five to ten percent of dogs! Puppies infected with roundworms often have poor growth. They are usually thin but have a swollen belly. Diarrhea, bloating, and vomiting may occur. In adult dogs, a roundworm infection often goes unnoticed.

Tapeworms (Dipylidium caninum)

Tapeworms live in a dog’s small intestine and can be transmitted by fleas. When a dog swallows an infected flea, the tapeworm can develop in its intestines. You will rarely see an entire tapeworm in the stool, but small segments or pieces may be present. Always deworm your dog if you notice these segments. Additionally, thoroughly clean the dog’s bed and cushions and control flea infestations.

Heartworms (Dirofilaria immitis)

Heartworms settle in the pulmonary artery and sometimes in the heart. They are transmitted by mosquitoes and are primarily found in warm climates, but are now also present in the Netherlands. Heartworms are becoming an increasing problem in Europe, so if you take your dog to Southern Europe, it is important to keep this in mind. Treating heartworms is difficult, so it is better to take preventive measures before traveling to areas where infected mosquitoes are present.

Hookworms (Ancylostoma caninum)

Hookworms attach to the intestinal wall and feed on the dog’s blood. They can enter through the skin or be ingested. Puppies, in particular, can become infected through their mother's milk.

Whipworms (Trichuris vulpis)

Whipworms live in the large intestine and feed on blood. Their eggs can remain infectious for years and are ingested through the mouth.

Symptoms of Worms or Parasites

If your dog shows certain symptoms, it is advisable to have its stool examined. Symptoms that require a stool test include:

• Unusual stool color, different from normal
• Diarrhea (especially black, with blood, or with mucus)
• Vomiting (especially with blood or bile)
• Reduced appetite
• Dull coat
• Weight loss
• Lethargic behavior
• Itching around the anus
• Worms in the stool