Giardia

Giardia are microscopic parasites that live in the small intestines of dogs and cats. Giardiasis, the disease caused by Giardia, is characterized by weight loss and chronic diarrhea. Giardiasis is treated with drugs that rid the body of the parasite and with medications to treat diarrhea.

Giardia (je-ar’de-ah) exist in two forms: teardrop-shaped trophozoites and oval cysts. Both forms are invisible to the eye, but can be seen with the aid of a microscope. Infection occurs when a dog or cat ingests the cyst stage of the parasite. Non-infected animals usually acquire the infection when they come in contact with infected animals, cyst-laden feces, or contaminated food and water. Likely places of infection include kennels and vacation sites, especially mountainous areas. Giardia cysts may survive for weeks in cold, wet climates.

Once in the dog’s or cat’s small intestine, the cyst matures into the trophozoite form, which attaches to the lining of the digestive tract. Five to 10 days after infection, trophozoites and cysts appear in the stool of the newly infected animal. These cysts serve as a source of infection for other animals. Younger dogs and cats (less than three years old) are most susceptible, especially animals less than 12 months of age.

People are also thought to be susceptible to Giardia infections acquired from pets. Therefore, all animals with giardiasis should be treated to reduce the chance of human exposure.

Diagnosis

Microscopic examination of fresh stool specimens by your veterinarian is the usual method of finding Giardia; however, cysts and trophozoites may only appear sporadically in the stool. Therefore, several microscopic examinations of feces over several days may be required to establish a diagnosis. Specialized techniques such as obtaining a sample of the contents of the small intestine with a catheter or an endoscope may be helpful. These contents are then examined under a microscope. Some veterinary laboratories are capable of diagnosing Giardia infections through the use of special tests.

Treatment and Home Care

Several drugs exist for killing Giardia in your pet’s digestive tract. Animals with severe diarrhea may require anti-diarrheal medications as well. Control measures should also be used to prevent re-infection and lessen the chances for human infection. Stools should be removed from kennels, yards, and litter pans daily. Drying will destroy Giardia cysts, so litter pans and kennels should be kept as dry as possible. Disinfectants such as dilute chlorine bleach effectively reduce Giardia cyst contamination in areas where disinfectants can be used.

Dietary Plan

If your pet has giardiasis, your veterinarian may suggest a dietary change based on your pet’s age and body condition, the degree of diarrhea and weight loss, and the presence or absence of disease in other organs and body systems. If your pet has a severe infection, your veterinarian may give you special feeding instructions. Some patients benefit from foods with increased levels of protein and energy during the recovery process. After your pet’s recovery is complete, your veterinarian may recommend another dietary change. Optimal nutrition should provide for a pet’s needs during each stage of its life. Optimal nutrition should also reduce the health risks associated with feeding excess levels of nutrients such as sodium, calcium, phosphorus, protein and fat.