(1) Anus (2) Rectum (3) Base of caecum (4) Small intestine (5) Kidney (6) Liver (7) Diaphragm (8) Oesophagus (9) Large colon (10) Caecum (11) Small colon
The digestive organs consist of the mouth, pharynx, esophagus, stomach, intestine and anus. They are all lined with a muscus membrane.
The mouth is an irregular cavity containing the organs of taste, and the instruments of mastication (chewing or grinding). The mouth is located between the jaw, it has two openings, the anterior, for the introduction of food, and posterior, through which the food passes into the pharynx. From the pharynx, the food is passed into the esophagus.
The esophagus, or gullet, is a muscular tube connecting the pharynx to the stomach.
The stomach is a pear shaped organ located in the abdominal cavity, close to the diaphragm. It's internal coat is divided into right and left portions. The left is the cuticular portion and is continuous with the mucous membrane of the esophagus. The right portion, the villous, or tube digestive coat is filled with blood vessels and contains the peptic glands which secrete gastric juice. the cavity of the stomach holds about 3 to 3 1/2 gallons. This is small in proportion to the size of the horse.
The intestines are divided into large and small. The small intestines are continuous with the stomach. They are about an inch in diameter and about 72 feet long. The large intestines extend from the termination of the small intestines to the anus, and may be regarded as consisting of four parts, the caecum, great colon, floating colon, and rectum. The large intestine measures about 22 feet long. The lining of the intestine is covered with villi which absorb the nourishing parts of the food.
The anus is the posterior opening of the alimentary canal and lies below the root of the tail.
The liver is the largest secreting organ in the body. It weighs from 10 to 12 lbs. It is situated behind the diaphragm and in front of the stomach. The liver secretes a fluid called bile or gall which is emptied directly into the small intestine. This is because the horse does not have a gall bladder.
The pancreas sometimes known as sweet red, is found behind the stomach and in front of the kidneys. It weighs about 17oz. It's function is to secrete pancreatic fluid, which is poured ino the small intestine and helps with breakdown of sugars.
The abdominal cavity is a large oval cavity bounded above the muscles of the back, below by the abdominal muscles, and in front by the diaphragm. The cavity is lined throughout by a serous membrane called ther peritoneum.
The kidneys are responsible for controlling body fluids and electrolytes, and excreation of many waste products from the blood stream and into the urine.
The Large Colon and the caecum allow bacteria to break down the cellulose of the plants that make up the horse's diet. The large colon is a 5 1/2 metres "tube", approximately 70 litres in capacity. Food then passes through the small colon to the rectum.
