Q. What are the clinical signs horses might present with that could indicate hindgut problems?

A. First, it’s important to note that the hindgut (the cecum and large colon, aka the large intestine) in the horse is approximately 26 feet in length and plays a huge role in water absorption. This needs to be considered when looking at clinical signs associated with hindgut problems. Horses can have essentially no clinical signs with early changes in the hindgut. This is seen in horses that eat an excessive amount of grain (grain overload). Initially they seem fine, but eventually as that grain (high in starch and sugars) reaches the hindgut, and they develop lethargy, stand or walk with the head low in a depressed stance, have a decreased appetite, eventually go off feed completely and then develop sore feet from onset of founder. With chronic hindgut issues they can have intermittent diarrhea, intermittent colic, and eventually lose weight.  They might also develop gas distension in the hindgut (can be painful), pass lots of gas, and develop intermittent colic and diarrhea.

Certainly, in horses with hindgut signs, there is inconsistent manure output and diarrhea and over time can lead to increased heart rate and/or respiratory rate, going off feed, and just feeling sick. With chronic hindgut problems, some horses might develop yellow gums, which means they have not been eating very well. Even though when you put the feed in there, sometimes they look like they’re eating, but the horse is not able to utilize it properly for energy. The hindgut is the primary energy-producing organ in the body as feedstuffs are converted into volatile fatty acid and utilized for energy.

As the problems become even more chronic, sometimes you’ll see ventral edema (under the stomach at the midline). This is fluid accumulation under the skin. If the horse’s protein levels fall low enough, they might develop edema in the limbs (stocking up), especially when standing in the stall, but this can also happen when they’re out on pasture.