EQUI 3644 The digestive system of the horse

The digestive system  All the parts that converts feed to a form for maintenance, growth and reproduction  Starting with intake through expelling feces  Simply stated: it is a long tube the runs from one end to the other

Mouth  Intake:  Parts:  Lips  Tongue  Mandible  Maxilla  Teeth  Salivary glands  Soft palate  Pharynx

Pharnyx  Short muscular tube that connects the mouth and esophagus.  Forces food from the mouth into the esophagus.

Esophagus  Simply a tube from the mouth to the stomach.  Food and water are moved to the stomach by waves of muscular action (involuntary muscles)Peristaltic action  Enters the stomach at an oblique angle, making regurgitation impossible  If food or water comes back through the nostrils, it indicates a blockage in the esophagus.

Stomach  U shaped muscular sac directly past the diaphragm  Holds food for initial digestion  Gastric juices are introduyc3ed that begin the digestion of the food taken in by the mouth.  Peristaltic action continues – food is squeezed and pressed by the action of the smooth muscles of the stomach

Small intestine  Long thin tube from the duodenum at juncture of intestine and stomach  Three parts  Duodenum  Jejunum  ileum  Approximately 2 inches in diameter, may be up to 70 feet long.  Average size horse holds about 12 gallons  Arranged in U-shaped curves  Held on the left flank by suspensory membrane: mesentery

Large intestine  Divided into:  Cecum  Large colon  Small colon  Rectum  Anus

the cecum is green, the colon is orange, the small intestine is yellow, the stomach is red, the rectum is blue, and the anus is brown. The left side is the layout as it is in a live horse, the right side is the intestines spread out so everything is able to be seen.

Cecum  Because of the large amount of cellulose in the horse’s diet, time is needed to break it down into useable nutrients. This is done by bacteria.  Cecum:  Elongated sac that extends from high in the right flank downward and forward to near the diaphragm.  The openings from the small intestine and large colon are close together in this organ  Contents are liquid  4 feet long with a capacity of about 8 gallons

Large Colon  10 – 12 inches in diameter  12 feet long  20 gallons capacity  Extends from the cecum to the small colon  Usually filled with food  Some bacterial action and nutrient absorption

Small Colon  4 inches in diameter  10 feet long  Extends from the large colon to the rectum  Balls of dung formed in the small colon – result of peristaltic action  Most of the moisture in the food is reabsorbed in the small colon

Rectum and anus  Rectum  12 inches long  Extends from the small colon to the anus  Holds feces as they move from the small colon  Anus  Opening where feces are expelled  End of digestive tract

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