The Horse Digestive System – How It Works and How You Can Keep it Running Smoothly

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The Horse Digestive System

The horse digestive system is not difficult to understand. Understanding how horses’ digestive tract works will help horse owners feed smarter and prevent digestive related illnesses.

Mouth

As with all mammals,digestion starts with mouth. Using their lips, tongue and teeth horses grasp food and break it down using  their 3 saliva glands and 36-40 teeth. To effectively chew a horse’s jaw combines lateral and vertical motions. These sweeping jaw motions mix the feed with saliva and kickstart the digestion process.

Esophagus

The horse’s esophagus is a simple tube that delivers food from the mouth to the stomach. A horse’s esophagus is roughly 1.5m in length. With such a far distance to travel food that isn’t properly broken down can get lodged in the horses throat and cause them to choke, this is why maintenance of a horse’s teeth is so important.

Stomach

Perhaps the most important part of the horse digestive system, a horse’s stomach is relatively small and only makes up about 10% of digestive system. The horse’s stomach contains 3 sections – the saccus caecus, fundic and pyloric. The saccus caecus is where the stomach and esophagus meet. When food hit this section pepsin and hydrochloric acids breakdown it down. Under normal circumstance fermentation will slow down and eventually stop, however if it does not the stomach will fill up quickly. The combination of fixed size stomach and fermenting foods will cause a build up of gas and potentially gastric colic.

Next the broken down food reaches the fundic region. Here lipids and proteins are drawn out and degraded from food before it moves onto the pyloric region. The pyloric area is where the stomach and small intestine join, most protein is absorbed in this stage.

Small Intestine

Next on the horse digestive system tour we hit the small intestine. Making up about 28% of the horses’ digestive tract, it is 15-22m long and does a majority of the digesting. Pancreatic enzymes aid in digestion and nutrients are then absorbed through the walls of the small intestine and deposited into the blood stream. Through the blood stream nutrients are delivered to whichever cells need them. Horses, unlike cows, don’t have bacteria in their small intestine, therefore any toxins that are digested are carried directly to the blood stream. That is why feeding moldy hay or feed is such a hazard to horses.

The more digestible grain is the more work can be done in the small intestine, this leaves less work for the large intestine and lowers the risk of colic, laminitis and acidosis.

Large Intestine

Also know as the hind gut, the large intestine contains the caecum, colon, rectum and anus. Containing 62% of the digestive system, it is 7m long. The digestion that occurs here is more microbial rather than enzymatic.

Fermentation begins in caecum and food will normally remain there for about seven hours. Here vitamins, fatty acids and some proteins will be absored. Next food moves to the large colon where most of the leftover nutrients will be absorbed. Fibrous materials are mostly digested in the large colon but too high of a fibrous diet can cause of twisted gut colic.

Next, whatever is left moves to the small colon. By now most useful nutrients have been absorbed and whatever is left is waste. The main job of the small colon is to reclaim excess moisture and return it to the body. Horse fecal matter is shaped during this process into ball shapes are sent to the rectum and out through the anus.

FAQ

How many stomachs does a horse have? Horses are non-ruminants, therefore they only have 1 stomach.

Can horses vomit? Horses can’t throw up. The valve between their stomach and esophagus only operates one way, unlike humans.

Should you feed horses hay or grain first? Grain is more dense and will stay in the gut longer but no study has identified an advantage either way.

When fed correctly, the horse digestive system works like a well oiled machine, but experienced equestrians know how sensitive the horses’ gut can be. Colic, ulcers and other digestive tract issues are common in horses and often take veterinary interference to resolve.