Secrets of the Stool Sample

We veterinarians ask that you bring in a stool sample once or twice a year as part of a complete health assessment of your animal. Why do we ask you to do this? It’s not because of some strange sadistic tendencies – the way we test your commitment to your animals, or because we’re in a stage of arrested development (although as sticklers to detail it could be argued that many are), but because the stool sample can reveal much important information about a patient’s health. While medieval kings had physicians whose primary task was to assess their daily output as a way of making sure the king was healthy, we’re able to examine these samples in a more highly scientific way. It’s helpful if you bring in a fresh sample. The parasites can live a long time in the environment though, so a sample that’s up to a few days old can still yield good results. We always are amused by those dried out cat donations that resemble a Tootsie Roll rolled in crushed almonds. Google “litter box cake” if you need some ideas for next April Fool’s Day.

Once you hand over the bag of that precious cargo, a few different tests are routinely performed. Some of these can be done in the hospital. Some are so specific that they must be handled at an outside lab. Generally, the sample is mixed with a special solution and then processed in a way to encourage any microscopic parasites or parasite eggs to rise to the top of the sample and stick to a microscope slide so it can be examined under a microscope. Take a look at what we can see under the microscope:

Intestinal Parasites:






Single-Celled Organisms




Bacteria – Salmonella, Botulism, etc

Parasites Of Other Organs:


Liver Flukes 

External Parasites:



Ear Mites


(These may be present if an animal ingests these while grooming and then passes them in the stool)

You can see there’s a lot of information contained in that little plastic bag. I’ll discuss each group of parasites in future posts. Once we determine what may be infecting your animal, appropriate medication can be given and preventative measures recommended in order to avoid re-exposure and re-infection.  We can also have specific testing such as cultures and DNA testing performed at our lab to determine the presence of a specific organism that may have not been seen during the microscopic exam. Many of these parasites are also capable of infecting people. Examining and properly treating your animal will also protect you and your family.

What if the sample is negative? This means none of the above was seen during the microscopic examination. Congratulations! This can indicate that your parasite control program is effective and you’re keeping your animals free of these diseases.  However, a negative sample can also just simply mean that the organisms were not shedding eggs in that sample or none were present in the one we examined. It is still possible that an animal is infected but it just did not show up as so in this single test. We often will recommend treatment “just in case” if an infection is suspected in order to avoid worsening problems.

There really is a lot of information to be gained from examining your animal’s stool. Don’t be embarrassed next time you need to bring in a sample. You’re practicing good animal care.  I often amuse myself in thinking that in a thousand years when someone digs up our civilization, they’ll find we revered our animals. Then it will be found that we even had people whose job it was to clean up after those animals and there were even doctors dedicated to taking care of them. So in a thousand years we may be seen as something like people – animals – animal caretakers. Yep, we vets will end up lower than your dog. Which is just fine with us. We’ll still know the secrets of the stool sample.


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