*Warning: graphic images of poop.*

By and large, equestrians are a group of people who, compared to the general public, are super down with close daily contact with feces.  You would be hard pressed to find an equestrian, ritzy or otherwise in their street clothes, who hasn’t resigned themselves to getting a little sh*t under their nails and shoveling.

As a chimpanzee researcher who studied fecal parasites near-daily for more than a year, my relationship with Number Two is… definitely more friendly than I had ever intended. When you work around something every day, well, the disgusting becomes truly mundane.  This one time, as a chimp sat overhead and contemplated his wake-up pooping, I contemplated trying to stand below him and just catch the sample in my gloved hand so it would never hit the ground and be contaminated.  The consequences of a direct hit that wasn’t in my gloved hand, however, were too high and I backed down – the better decision.  Grossnasty as it may be, there’s a lot we can learn from poop – as one non-scientist put it to me once, “95% of talks on biology come down to feces!” – and to ignore it is to your own detriment, and your horse’s.

I’ve got you under my skin

I hesitate to call gastrointestinal parasites the “most well-known” of the things we study about poop, but I would say that everyone has some idea that they exist and that can cause problems.  Far from being near-invisible demons, GI parasites are actually super easy to visualize. Many of them can be seen (if present) with simply a sample, a basic compound microscope with at least 100x zoom (10x objective, 10x lens usually works), and a slide kit.  I can’t recommend you try to find them in your local science lab, as playing with feces without certain safety precautions breaks most standard health and safety regulations because of general hygiene rules and a small risk of zoonosis.  They’re also really hard to find if you’re not sure what you’re looking for.  But I’ve found lots before, so you can enjoy my pictures (though it should be noted these are just examples of parasites, as they are all primate parasites and not equine ones).

Larval 745 Larval 745

Larval and adult thread worms at the same magnification

Eggs 2 745

eggs 745
Pinworm (Enterobius spp.) eggs and Strongyloid egg

So we all know that worms cause disease and are really bad, right?  Or are they?  Interestingly, there’s a lot we don’t know about how gastrointestinal parasites interact with our bodies – for humans or animals.  It is very clear that certain parasites, especially at high densities, are very detrimental to health and are consistently associated with morbidity and mortality.  However, most organisms live with low-level GI parasite infection for their entire lives and do just fine – so what’s going on there?  Some parasites, for example some of the hairy, ciliated badboys below, are even thought to assist in digestion of fiber.  Hopefully, increasing research into the gut microbiome will help us learn more.

Primate poop  More primate poopCiliated single-celled eukaryotes (once again, examples from primates)

Most equestrians deworm on a fairly regular schedule, whether by the rotation method or using a fecal egg count, but I won’t be debating the merits of those here (we could talk for days about them!!).  I love the idea of bringing science into deworming, but from studying poop parasites I am all too aware of the complications in interpreting egg count results.  However, I haven’t been trained in equine egg count methods, so if you have a veterinarian or clinic that you trust, use their opinion instead of mine!!  And decreasing antiparasitic resistance in common parasites is important, so consider carefully which you choose, and consult with your veterinarian or barn manager.

Though this isn’t especially relevant to horses, many strongyloid parasites do something called “larval migrans” when their free-living larval stage is looking for the right place to grow up and breed.  Essentially, they enter the body through the skin and just crawl around until they find the appropriate organ to inhabit.  You can find truly disgusting videos and pictures of this all over the internet.  Suffice to say, you do not want parasites crawling under your skin trying to find an organ to breed in, and you definitely do not want them to be parasites that don’t even normally live in mammals.  That would be rather unpleasant.  Take it from someone who knows.

Timing is everything

You’ve probably noticed that your horse generally makes a deposit at about the same time during your tack up, ride, or cool down routine.  Much like Dr. Sheldon Cooper and the chimp I mentioned above, horses tend to have a bathroom routine that makes them most comfortable.  Murray, for example, always poops within 5 minutes of me getting into the saddle, and typically once or twice more during a regular ride.  My very good friend Mariko, who helped me edit this blog, feels like her ride isn’t complete without her horse’s post-ride pooping and groaning sequence.

You should know what is your horse's "normal"

You should learn what is your horse’s “normal”

It’s important to learn what is normal for your horse (or self, but I’m not dishing out advice for humans officially) so you can notice differences that might point to some kind of GI upset or other problems.  So in addition to keeping an eye out for a poop-less stall as a sign of colic, keep an ear out for when your horse might be pooping more often than usual.  We all know that fecal output can increase when scared (when you’re walking through the bush and suddenly see a lion, your body screams “Lighten the load!! You’ll run faster”), so paying attention to times that your horse is pooping more (or less) than usual can help you understand how she feels about work, housing changes, or her neighbors (a stretch, but poop contains a lot of information with a good olfactory system!).  When Murray poops a lot (four or more times) during a dressage ride, and the volume starts to get smaller and smaller, I know I’m stressing him out and need to back off with what I’m asking.  If he isn’t pooping, I know I could ask a little more, and should see if he’s pooped a lot recently because that is weird.

George Morris insists at his clinics that when a horse is defecating, just put on more leg!  I too don’t want my horse stopping in the middle of a championship jumper round to drop the kids off at the pool (not that I’ve ever been to a championship round, but my trainer’s 3’6” jumper pony did that one year!), or sullying the dressage court with a steaming load, but I might be a little more inclined to forgive than George.  All I want is for Murray to keep moving forward while he’s pooping, and if we can do that, I know we can recover the round.

Ike's poop

Ike’s poop

Horse poop 1

Festin’s poop


Carter’s poop

Red and yellow and pink and green, purple and orange and blue – I can see a rainbow

Fecal color can be influenced by feed and hydration, and once again, it’s very important to learn the normal state of your horse’s barn-aisle gifts.  Every horse is a little different, and while Murray’s poop is normally fairly solid, well-formed and brownish, my roomie’s mare’s tend to be a little softer and greener.  Greener can be associated with alfalfa intake, and beet pulp can lead to a reddish-brown ball that may be sticky.  This is all okay, as long as that is the norm for your horse.  Not okay (for you, your dog, or pony!) are black stool or stool flecked with red – this can indicate bleeding in the GI or colon, respectively.

What can we deduce from the loose deuce?

Ah yes, the most glamorous and splashiest (too soon?) aspect of fecal monitoring: diarrhea.  While there are many, many possible causes for loose stool, over-hydration is never one of them.  Make sure to take note and consult your vet, especially if the diarrhea is profuse, watery, or progressive and doesn’t resolve.  Horses can lose hydration very quickly through diarrhea, much more so than other animals, so it’s always something to pay attention to.  Chronic diarrhea is especially important to treat, and may require feed, turn-out, or even stabling changes.  Horses at my barn have successfully kicked the squirts by switching either to all-rye or all-alfalfa diets, adding a probiotic, or being turned out in our driest pastures.  As with all changes in diet, you need to give your horse’s body some time to adjust to the change before evaluating things and possibly making another change.

Too-firm of feces is also something to be worried about.  Your horse should not be shooting out small cannon balls, and this also suggests a lack of hydration (obviously if they have had some time to dry, they are allowed to be, and are perfectly viable as, cannon balls).  Poor hydration can have long-term impacts on the colon, as well as generally making it really unpleasant for your horse to pass these necessary byproducts.  Interestingly, lack of movement around pasture can influence the likelihood of constipation in your horse, so keep an eye on seniors that might be limited in their activity.

Murray normal

Murray’s “normal”

Have I said it too many times yet? Make sure you understand your horse’s “normal” for pooping.  The first time I took Murray to a show, I thought he was doing fine because his poops near the trailer were pretty formed, but once we got to the warm up he started squirting like a sputtery hose.  I immediately felt terrible about it, and not just because I could have been right there with him!  We didn’t compete that day, and I think it was probably best for both of us.  Fortunately for me, he’s had less and less diarrhea and even unformed feces with every subsequent trip off the property, and now an abundance of unformed feces is a warning sign to me.  Mariko’s horse has diarrhea almost every time he schools off-property, so she takes note of it and works to make sure he’s comfortable, hydrated, and that his tummy troubles don’t continue.

Though long and meandering, I hope this blog and the accompanying glorious pictures convinced you of the importance of setting up your own study in equine feces!