Parasitic Infection Symptoms in Dogs

Parasites often infect dogs, and recognizing parasitic infection symptoms is important in being able to get help when needed and keep your pet in good health. The parasites feed on the dog's nutrients and can weaken the dog. The symptoms of parasitic infections can vary depending on the parasite that affects the dog (there are more than a dozen types of parasites that can be present in canines). However, there are a few common symptoms that are clearly pointing to a parasitic infection.

Vomiting and Diarrhea

A lot of parasitic infections in canines will cause vomiting and diarrhea. These symptoms are due to the fact that the parasites, located in the digestive tract, will cause irritation and interfere with the normal digestion process. Vomiting and diarrhea may not be present in dogs that have heart or lung worms. Occasionally, the vomit or the feces may have blood or parasites.

Parasites in the Stool

Parasites can be often observed in the dog's stool, if the dog has intestinal worms. The worms may be smaller and moving or dead, but there may also be worm segments, which are indicative of a tapeworm infection.

Appetite Changes

Most commonly, a parasitic infection will make the dog eat less, as he will be sick and vomit a lot. However, there are also parasites such as tapeworms that will not affect the dog and may even make the dog eat more. This can be due to the fact that the tapeworm eats a lot of the dog's food, and the dog will feel hungry and will want to compensate for the lack of nutrients.


Dogs with a parasitic infection may experience fatigue, due to the fact that they will not get all the nutrients they need. The fatigue may also cause lack of appetite. The level of fatigue may differ; some dogs may be extremely tired, while others will not show a lot of signs of fatigue. This can depend on several factors including:

  • The dog's overall health
  • The age
  • The type of parasitic infection
  • The gravity of the infection

Coat and Skin Changes

The presence of internal parasites can have an impact on the appearance of the coat and skin of the dog. A dog with a parasitic infection will have dry skin with a coarse coat. The dog may experience hair loss. Fleas and other external parasites may also cause rashes and itchy skin.


Coughing is a symptom that is only present if the dog is affected by heartworms or lungworms. The coughing is dry and is heard mostly when the dog is resting. The coughing will only occur when the infection is severe.

If you notice any of these symptoms in your dog, you need to visit the vet. An overall examination and a few blood tests can help the vet identify the type of infection and recommend the best type of deworming or parasite treatment.