There are a number of tests that can be performed on your pet's stool sample to check for intestinal parasites. The most commonly performed test is a fecal flotation, so-named because a portion of the stool is mixed with a special solution that has a high specific gravity. That means the lighter components of the stool sample will float to the top while the heavier debris, such as undigested food, will sink to the bottom.
After a fecal flotation test is set up, it is necessary for it to process for 10 to 15 minutes. During that time debris that has no diagnostic value sinks, and if parasite eggs are present, they will float to the top. A cover slip, a very thin piece of glass, is placed on top of the sample when the test is first set up and the eggs will stick to the cover slip. When the timer goes off, the technician or doctor picks up the cover slip and places it on a microscope slide allowing any eggs that are present to be seen.
The most common parasites seen on a fecal flotation are two forms of nematode worms: hookworms and roundworms. These worms are frequently present in the small intestine of young pups and kittens, though hookworms may infect dogs and cats of any age.
Hookworms get their name from the hooks around their mouthparts. They use these to pierce the wall of the intestine, then they feed on the blood. Hookworms are tubular, so picture a small straw attached to an open blood vessel, blood running through it into the stool, and you can see how hookworms can quickly cause a life-threatening anemia.
Roundworms also can cause severe gastrointestinal inflammation, even blockage of the intestine, if their numbers are great enough.
Both hookworms and roundworms can infect people, so there is a public health concern regarding both parasites. Be sure to pick up your pet's stool from the yard or kennel at least once daily and flush it down the toilet. Wash your hands thoroughly with soap and water after handling the stool in any way.
Another common worm found in dogs' but not cats' GI tracts is whipworm. Living at the junction of the small intestine and large intestine, whipworms can cause large bowel or small bowel dysfunction. Mucus and straining associated with colitis are common signs that whipworm is present.
A protozoan parasite of young animals, especially those born or reared in filthy conditions, is Coccidia (COX-id-eee-uh). Coccidia also can cause severe diarrhea, weight loss and even death. Like human infants, young animals lack the ability to store reserves of fluid and energy and can quickly dehydrate and succumb.
Thus, a semiannual stool test, or at least an annual test, is important to catch infestations early.
Cases in which other parasites are suspected may require different testing of the stool. For example, the common protozoan parasite Giardia (gee-AHR-dee-uh) often doesn't float in high-specific gravity solutions. It is best found in a test called direct smear, using a small sample of stool and spreading it in a saline solution directly onto the microscope slide for direct examination. Sometimes these same slides may be dried, subjected to stains and examined under even higher magnification.