Protozoan Diseases in Dogs (cont.)

Giardiasis

This disease is caused by a protozoan of the giardia species. Dogs acquire the infection by drinking water from streams and other sources that are contaminated with infective oocysts.

Most infections in adult dogs are subclinical. Young dogs can develop a diarrhea syndrome characterized by the passage of large volumes of foul-smelling, watery, or “cow-pie” stools. The diarrhea maybe acute or chronic, intermittent or persistent, and may be accompanied by weight loss.

Diagnosis is made by finding the protozoan or its characteristics oocysts in saline smears of fresh stool. Smears from rectal swabs are satisfactory. A negative smear does not exclude giardia, as oocysts are shed only intermittently. Three negative fecal smears collected at least two days apart should be obtained before the diagnosis is excluded. Serology tests (ELISA, IFA) are now available.

Treatment: Giardiasis responds well to Flagyl (metronidazole). Because Flagyl causes developmental malformations in the fetus, it should not be administered to pregnant bitches. Other effective drugs are available. There is now a vaccine available for giardiasis, but this is rarely recommended because the disease is usually mild and responds well to treatment.

This article is excerpted from “Dog Owner’s Home Veterinary Handbook” with permission from Wiley Publishing, Inc.