Digestion

Horses have a monogastric digestive system, they have one stomach which means they have one chance to digest their food. A monogastric digestive system works as soon as the food enters the mouth, so the mouth is a critical part to digestive health. The incisors bite the fibers, the tongue then passes it to the molars to grind the fibers. The physical breakdown of food is a necessity to be able to properly digest. Horses create more saliva the more they chew. The enzymes in the saliva initiate digestion. The mouth also plays a role in digestive pH and impacts the microbial populations and disease processes. 

 When horses chew, their jaw articulates laterally (side to side), not up and down like humans. Horses adjust their chewing pattern accordingly to the fiber levels of the food (long stem hay vs pellets). The horse swallows the food bolus, and it travels down the esophagus into the stomach. Due to the sharp angle where the esophagus and stomach meet, horses are incapable of vomiting which is why colic is fatal. In the stomach, where 1.5 liters of gastric acid is secreted every hour, the food is broken down into starch, fiber, protein, and fat. The stomach is small and can only hold about 4 pounds of food at a time. Thats why smaller meals more often are desired. The small intestines are 70 feet long and the primary site for enzymatic digestion. Starch, proteins, and fat are digested in the foregut, along with the absorption of amino acids. The hindgut includes the cecum and large intestines, it is 25 feet long and primary role is to digest and absorb fiber. Fatty acids are absorbed through the lining of the large intestine. Horses should never go long periods of time with no food, they need constant forage to help buffer the acid in the stomach, especially in stressful situations when performing and trailering.

Oral bacteria have a huge impact on gut health. A horse with periodontitis or gingivitis has higher levels of bacteria festering in the mouth, usually from a diastema or periodontal pocket. Bacteria is swallowed with saliva and feed, and when the body is in a diseased state the bacteria colonize in the intestine and compromise the immune system. Routine dental exams, cleaning out periodontal pockets and diastemas reduce the oral bacteria in the mouth, which then reduces it in the gut.

Dentistry is vital to keep the horse chewing correctly to properly digest their food. They chew more when they have a high fiber diet (forage like grass and hay). When there is a restriction in the mouth such as sharp points or hooks, the jaw loses range of motion. The less range of motion and surface-to-surface contact the teeth have, the less they can grind their food. Food not ground will pass and not be digested. Which means more money spent on feed!

Seniors with limited to no occlusion that can't chew hay enough need to be supplement with pre ground forage such as chopped hay or soaked hay pellets or cubes. Soaking a mash will help them moisten the food enough before swallowing reducing the risk of choke or impaction colic. 

A forage-based diet low in starch with balanced trace minerals is the healthiest diet to support dental health.