Problems related to the sensitive equine digestive system represent one of the most common medical problems seen by veterinarians. The design of the horse’s digestive system meets the specific needs of an herbivore: absorption of nutrients from fibrous plant material.
The equine digestive system begins at the mouth. Food enters the mouth; chewing action, from the large molar teeth, grinds the food into smaller particles. Oral enzymes act on the food particles to begin the digestive process. From the oral cavity, the road to digestion leads down the four foot long esophagus to enter the stomach. Once in the stomach, secretion of acids further separates food particles. As food material enters the small intestine, pancreatic secretions and bile begin to digest fats, simple sugars, and proteins. Food material not digested in the 50-70 feet of small intestine enters the cecum for further breakdown. The four foot long cecum contains a delicate balance of bacteria to ferment the complex sugars (cellulose) that remain in the intestinal tract. After fermentation, cecal contents enter the large intestine. The large intestine contains two segments: the large and small colons. The 10 foot large colon absorbs the fermented sugars released from the cecum. The small colon absorbs water to maintain hydration.
Indications of problems within the equine digestive system include: lack of an appetite, drooling, looking back at the abdomen, kicking at the abdomen, rolling on the ground, weight loss, and poor performance. It is important to note that horses cannot vomit to expel stomach contents like many other animals.
Many digestive problems in horses result from dental disease, poor quality feed, and sudden dietary changes. Dental disease can be avoided by routine oral examinations by your veterinarian and floating the teeth. Poor oral health may cause: choke (esophageal obstruction), bowel obstruction, and colic. Dietary causes of intestinal upset can lead to colic: abdominal pain.
Causes of colic include :
- Colon torsion
- Gastric impaction, dilatation, and rupture from poor dental health or poor quality feed
- Gastrointestinal ulcers in foals
- Infectious causes: Salmonellosis, Clostridiosis, Potomac Horse Fever
- Large colon displacements
- Large colon impaction; enteroliths; sand impaction
- Parasites: Strongyles, Ascarids
- Toxins: Blister Beetles, Aflatoxins
Digestive problems in horses need to be treated aggressively to avoid the development of laminitis.