This is the major organ of digestion in the horse. There are many components to this digestive process. Bile constantly flows into the small intestine from the liver because the horse does not have a gall bladder in which to store it. After the food has been digested, it is absorbed through the walls of the small intestine and carried off by the blood stream to whatever cells need the nutrients. It can take as little as 30 to 60 minutes for food to pass through the small intestine.
Horses are very susceptible to colic or death from toxic materials in the feed.
Unlike the cow that has bacteria in the rumen that can detoxify materials before they reach the small intestine, toxic material a horse may consume enters the intestine and is absorbed into the blood stream before it can be detoxified. Therefore, it is very important not to feed horses moldy or spoiled feeds. Urea is a feed supplement fed to cattle that can be utilized in their rumen to make protein. Horses cannot use this feed supplement because it is absorbed in the small intestine before it can get to the cecum where it could be used. Urea can be toxic to the horse, but the horse can tolerate the level at which it is added to most cattle feeds.