Definition
Gastrointestinal refers to the digestive tract as a whole — the continuous tube that runs from the stomach through the small and large intestines, ending at the rectum. In equine medicine, the term encompasses the entire digestive pathway that processes ingested forage into nutrients and waste. Because horses are hindgut fermenters with a digestive system optimized for continuous grazing of fibrous plant material, the gastrointestinal tract is central to their health and a frequent site of disorder.
Structure of the Equine Digestive Tract
The equine gastrointestinal tract begins with the stomach compartment (stomach) compartment, which is small relative to the horse’s overall body size. The small intestine, approximately 20 to 22 meters long, handles enzymatic digestion and absorption of simple sugars, proteins, and fats. The large intestine — comprising the cecum, large colon, small colon, and rectum — is where hindgut fermentation occurs, with microbial populations breaking down structural plant carbohydrates (fiber) into volatile fatty acids that supply a significant share of the horse’s energy. The total length of the tract in an adult horse is approximately 30 meters, and it holds 180 to 200 liters of digesta and fluid.
Gastrointestinal Disorders
The complexity and size of the equine gastrointestinal tract make it vulnerable to several categories of disorders. pain from GI obstruction or displacement is the collective term for gastrointestinal pain and ranges from mild gas distension to life-threatening large colon displacement or small intestinal strangulation. Gastric ulcers affect the upper portion of the tract; large colon impactions affect the hindgut. Diet management — consistent forage access, appropriate concentrate levels, and controlled introduction of new feedstuffs — is the primary means of maintaining gastrointestinal health. targeted strongyle control via fecal egg count testing and targeted deworming directly protects the gastrointestinal tract from damage by strongyles and other helminths. Horses spending extended time without grazing or forage access are at elevated risk of both gastric and hindgut problems.
Further reading: Gastrointestinal tract on Wikipedia; Gastrointestinal tract at Britannica.