Educational Articles

Infectious Diseases

  • Giardiasis is an intestinal infection in humans and animals, caused by a microscopic protozoan parasite. The parasite occurs worldwide and is a common cause of "Traveler's Diarrhea" in people. Outdoor enthusiasts who inadvertently consume contaminated water may develop "beaver fever", which is another name for giardiasis in people.

  • Heartworms are a blood-borne parasite called Dirofilaria immitis that reside in the heart or adjacent large blood vessels of infected animals. The female worm is 6 - 14 inches long (15 - 36 cm) and 1/8 inch wide (5 mm). The male is about half the size of the female. Heartworm disease is much more common in dogs than in cats.

  • Heartworm disease is a serious and potentially fatal disease. It is caused by a blood-borne parasite known as Dirofilaria immitis.

  • Hepatitis is defined as inflammation of the liver. As a specific disease, Infectious Canine Hepatitis (ICH) is a viral infection caused by a member of the Adenovirus family.

  • Canine herpesvirus or canine herpes is a systemic, often fatal disease of puppies caused by CHV - Canine Herpes Virus. CHV is common worldwide in dogs, coyotes and wolves. CHV does not cause infection in humans. CHV may remain latent or "hidden and quiet" in tissues after a dog is infected and may be passed on to other dogs, particularly to fetuses developing in the mother's uterus.

  • Histoplasmosis is a chronic, non-contagious fungal infection caused by the soil-dwelling fungus Histoplasma capsulatum. Histoplasma capsulatum is found globally and may infect both humans and animals. However, histoplasmosis is uncommon to rare in all but dogs and cats.

  • Hookworms are intestinal parasites of the cat and dog. Their name is derived from the hook-like mouthparts they use to anchor themselves to the lining of the intestinal wall. They are only about 1/8" (two to three mm) long and so small in diameter that they are barely visible to the naked eye.

  • Hookworms (Ancylostoma caninum, Ancylostoma braziliense) are intestinal parasites of the cat and dog that get their name from the hook-like mouthparts they use to anchor themselves to the lining of the intestinal wall. They are only about 1/8" (3 mm) long and so small that it is very difficult to see them with the naked eye.

  • Inflammation of the inner ear is called otitis interna, and it is most often caused by an infection. The infectious agent is most commonly bacterial, although yeast and fungus can also be implicated in an inner ear infection.

  • This handout is designed to give you an overview of some of the internal parasites that can infect your cat. For more detailed information, refer to our separate information sheets on roundworms, hookworms, whipworms, tapeworms and heartworms.