Internal Parasites

Internal parasites can inhabit your pet’s gastrointestinal (GI) tract and, in some cases, may migrate to other organs such as the liver, lungs, nervous system, and heart. Fortunately, these parasites can be detected through proper testing easily done with your pet’s stool. We recommend testing a fecal sample at least once a year during your pet’s annual exam.

Common internal parasites that are found in the
GI tract include:
  • Coccidia
  • Giardia
  • Hookworms
  • Roundworms
  • Tapeworms
  • ​Toxoplasmosis
  • Whipworms
Diarrhea, vomiting, and weight loss can be among the most common clinical signs of GI parasite infections. However, many infected pets don’t show any clinical signs at all.

Dogs and cats can be affected by a range of GI parasites, some of which are visible to the naked eye, while others are microscopic. Pets are typically infected with these parasites through accidental ingestion of parasite eggs (which are microscopic) from areas that have fecal contamination from other infected animals. Alternatively, some parasites are acquired through ingestion of intermediate hosts such as rodents or fleas.

These parasites are also a health risk to humans and are considered zoonotic – meaning they can be transmitted from animals to people. For example, if a person accidentally ingests roundworm eggs, the larvae can migrate in the body and cause organ damage and potentially blindness. Infective hookworm larvae in the environment can penetrate the skin. When this happens in humans, the condition is called cutaneous larva migrans. People with this condition may experience itchy skin lesions with a snakelike pattern.

Because of the health risk to your family and pets, it is important to keep your pet on a year-round parasite prevention program. There are several preventatives that when used properly, are very effective at greatly reducing the risk of your pet acquiring intestinal parasites. Additionally, you can help prevent the risk of zoonotic disease in your family by practicing good hygiene (request hand washing), avoiding eating unwashed raw vegetables or undercooked meats, and cleaning up pet feces in your yard. For more information about pets and parasites, visit the Pets and Parasites organization, and consult with one of our friendly staff.

There are many effective products available today that can safely be used on dogs and cats to help protect them and control internal parasites. Fortunately, many monthly heartworm preventive medications also control some of these parasites.