Veterinarians’ Stool Testing

“OK, Mrs. Jones, we’ll see you at 1:50 with Snookers. And, if you can, try to bring a stool sample that’s not more than 24 hours old so that we can run a test for intestinal parasites.”

You get to the appointment with your pet’s doctor, and you give the receptionist the stool sample she requested. She disappears into the laboratory with it. What in the world happens to it then?

Actually, there are a number of tests that can be performed on your pet’s stool sample. 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 that the lighter components of the stool sample will float to the top (thus the name “fecal flotation”) 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 a period of 10 to 15 minutes. During that time debris that doesn’t have any diagnostic value sinks and if any eggs of parasites 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 present to be seen.

The most common parasites seen on a fecal flotation (you may sometimes hear staff members refer to the test as a “fecal”, or just FF) 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, which they use to pierce the wall of the intestine, causing bleeding. Hookworms then 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 can also cause severe GI 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, preferably as soon as he “goes”. Flush it down the toilet. Wash your hands thoroughly with soap and water after handling the stool in any way.

Another common nematode 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, or both. Mucus and straining associated with colitis are common presenting signs with Whipworms.

A protozoan parasite of young animals, especially those born or reared in filthy conditions, is Coccidia (COX’-id-eee-uh). Coccidia can also 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.

Now you have a better idea of what happens to that stool sample you so collected and took to your pet’s last doctor visit. Now you know that it’s more than a “worm test”, and is important for the health of your pet, and your family.

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  1. Dr. Randolph, in reply to your answer: My dog is a poodle. Weighs eleven lbs. She is eleven and a half yrs. old. (acts like a puppy). She has been spayed. Her diet is chicken white meat only. I cook it for her. She never has a bowel movement without some blood. Also never acts like she is in pain. When there is a lot of blood. I take her to the veterinarian. They put her on medicine. It helps a little. She has had thousands of dollars worth of tests. All say the same: colitis. I”m afraid she is losing too much blood. Also she eats Prescription Diet little bites, chicken flavored, because of stones in her bladder yrs. ago. I’m told to keep her on this diet. Any suggestions at all would be of great help too me. Thank you, Yvonne.

  2. My dog keeps getting colitis. Nothing seems to help her. It has been off and on for 7 yrs. now. Could you suggest a medication that would help?

    • Yvonne, colitis in dogs is a multifactorial disease, just as it is in people and cats. Please write back with your pet’s breed, age, gender, neutered or not, diet and medications used so far. Awaiting your reply, Dr. Randolph.

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