H O R S E A N D H E A LT H Non-glandular region of the stomach phosphorus and other minerals are absorbed into the bloodstream here. Finally, the ileum controls the flow of partially digested food (now consisting only of fibre and water) into the caecum of the large intestine.
THE LARGE INTESTINE The large intestine can be divided into three parts: the caecum, the large colon and the small colon. The caecum is a large, blind-ending sac. It is over 1m in length and can hold 25 litres or more of liquid. It is the equivalent of the human appendix. The caecum contains many millions of gut flora or beneficial bacteria, whose job is to break down the fibrous material from the diet, which is all that remains after the nutrients have been removed in the small intestine. There are many types of bacteria, each specialising in processing a particular foodstuff, although they can adapt to the kind of food eaten over time. This is why it is important to make any changes in the horse’s diet gradually to allow the flora in the caecum to adjust to the change. The action of the bacteria digesting the fibre in the caecum produces fatty acids and vitamins B and C, which are then absorbed. Water is absorbed throughout much of the system and also from the caecum. Bacterial action continues inside the large colon but with fewer bacteria involved. The breakdown of food in the large colon can take several days, which explains its large size. The space inside the abdominal cavity is limited, so the bulky colon must be folded to fit into it. These tight bends in the folds can become blocked with food, giving the horse colic. Parts of the large colon can also become twisted around one another, cutting off the blood supply – and again resulting in colic. The small colon (also known as the descending colon) will absorb water, electrolytes and any remaining nutrients that are left after transit through the caecum and large colon.
Cardiac sphincter Oesophagus Pyloric sphincter
Glandular region of the stomach
Duodenum
THE RECTUM AND ANUS The remaining fibrous waste is expelled as manure through the rectum and anus.
organs in the body as many digestive processes occur here; it detoxifies the blood; and it plays a major part in protecting the body from disease and infection. The liver has a double blood supply; it receives oxygenated blood from the hepatic artery and deoxygenated blood containing nutrients directly from the small intestine via the hepatic portal vein. Blood from both vessels enters the lobes of the liver, where oxygen, most of the nutrients and several toxins are removed by the hepatic cells. From here, the nutrients are either stored in the liver or sent out into the body; the toxins are either neutralised or stored; and the blood is returned to the heart through the main blood vessel, the vena cava.
THE LIVER The liver is the largest gland in the horse’s body, weighing 5kg. It is located inside the abdominal cavity against the back of the diaphragm. It is also one of the most important
The major functions of the liver include: • Processing protein, carbohydrate and fat • Storing vitamins • Secreting bile to be used in the small intestine for
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