If you have a veterinary textbook somewhere on your shelves, chances are you’ve seen one of those photos of a sick horse’s innards-miles and miles of wet, purplish loops of intestine, spilling out in all directions. The poor equine posing for that photo had no doubt expired by the time the flash went off, and chances are he only ended up being an intestinal poster boy because he’d been opened up by veterinary surgeons in a vain attempt to save him from a case of severe colic.

What’s my point? Well, the very thought of the sheer size and volume of the equine gastrointestinal tract makes it tough to visualize, much less understand. It’s huge, it’s daunting, and it’s persnickety to boot. But if you’d rather your horse didn’t end up on the operating table, opened up from stem to stern, it’s vital that you have an idea of how his digestive system functions, and what you can do to help keep it happy. Let’s take a look inside.

Inside The Gut

At first glance, the design of the equine digestive tract looks like an evolutionary mistake. The stomach, for example, is surprisingly small for an animal the size of the horse, with a capacity of only about two to four gallons (7.5 to 15 liters). In contrast, the small intestine can reach an amazing 70 feet (about 22 meters) in length if uncoiled and stretched out, with a diameter of three to four inches and a capacity for 10 to 12 gallons of material. Compared with what we know about the GI tract of other animals, the equine gastrointestinal tract seems strangely out of proportion. But from Mother Nature’s point of view, everything’s just fine. In his wild state, the horse never expected to ingest large quantities of food at one time; his digestive system is optimally designed for his wandering, grazing lifestyle, which introduces small amounts of food to his system almost constantly