A Horse’s Digestive System

As a follow-up to last week’s blog about the benefits of allowing your horse to forage in a pasture and how it helps your horse’s digestive system, I want to go a little deeper into how your horse’s digestive system works.

Sometimes we think that our horses are similar to humans in certain ways, but when it comes to their digestive system they are very different.

I’ve heard people say that their horse’s digestive system is delicate and others say that their horse’s digestive system is as strong as steel.  Well, I think it depends on what and how you feed your horse.

Many of the common digestive system problems that horses have are due to the unnatural way horses are sometimes fed.

If you look at horses before they were domesticated or wild horses with thousands of acres to roam, they mainly graze on grasslands.  Horses are natural herbivores.  It’s not like they have someone feeding them “other stuff” out in the wild.  Usually, their only concern is looking out for their own safety and staying away from predators.

Now, with domesticated horses, we have to think about what we feed our horses and how it affects their health and digestive system.

According to the research, horses naturally need at least 10 acres of pasture, per horse, in order to have enough free-range forage to eat and enough space to get the proper exercise to stay healthy.  This minimum amount of acreage also minimizes the exposure to parasites as well.

But if we don’t have that much space, we supplement that natural requirement by feeding hay, riding or lunging for exercise, and using dewormers for controlling parasites.  These aren’t bad for our horses; they actually help if our horses don’t have access to a minimum of 10 acres per horse.

We do what we have to in order to keep our horses healthy and happy.

Here are a few things that you should know about your horses’ digestive system:

1. Horses have a simple stomach, not two as some people may think. Their digestive tract is unique though because it digests portions of its food enzymatically first in the foregut and then ferments the food in the hindgut.  So I understand how the horse’s stomach is sometimes thought of as being in two sections.

2. As mentioned last week, horses only produce saliva when chewing forage. And this saliva is crucial for neutralizing stomach acids and reducing the risk of gastric ulcers.  Your horse should be producing up to 10 gallons of saliva per day for a healthy digestive system.

• When your horse chews his food into smaller particle-size portions it also mixes with his saliva which begins the digestive process. The saliva acts as a lubricant for easier passage through the esophagus and buffers acids in the stomach, as mentioned above.

3. Horses have been noted to only chew on one side or the other. Research shows that they chew on a slant, outside to inside motion and the motion is determined by the slant of the upper and lower cheek teeth.

• The chewing action of horses incorporates both lateral forward and backward motions and vertical motions. This allows the food to effectively be ground and mixed with saliva to start the digestive process.
• An average horse will generally take 60,000 jaw sweeps per day while grazing.

4. As mentioned last week, the water level in your horses’ grass helps small sections of food flow easier into your horse’s stomach. Your horse’s esophagus, which empties into the stomach, only flows in one direction. So it is very important for smaller sections of food to flow easily as your horse cannot regurgitate or vomit the food if there’s a problem.

• This is also important because the gastric capacity of your horse’s digestive system can only hold 8-10 liters.
• Water only remains in your horse’s stomach for about 15 minutes before moving on to the small intestine. If you feed flakes of hay, it can be beneficial to have the water trough close by or to add some water to the hay before feeding.  Just enough to help the flow, but not enough to cause mildew or mold.
• Because your horse’s esophagus is long and only goes one way, incorrectly chewed large pieces of food like carrots, etc. can lodge inside and get stuck causing your horse to choke. This is a good reason to feed in small portions and also to keep your horse’s teeth well maintained.

5. Your horse’s digestive system can benefit from small frequent meals which can be done using a slow feeder or having access to a grass pasture. Because when a horse’s stomach is empty, acid can attack the cells in the stomach lining causing ulcers.

• A horse’s stomach can only hold about two gallons of food. Which is quite small compared to the other parts of their digestive system.
• The stomach’s main functions for a horse include mixing, storage, and controlling the release of food into the small intestine.

6. Horses do not have a gall bladder so their small intestine aids in the digestion of sugars, starches, proteins, and fats. When too much sugar and starch spill over into the colon, this can potentially cause your horse to have colitis and diarrhea.

• The passage of food through your horse’s small intestine is very quick. It moves at about 1 foot per minute.
• The small intestine is where the food is broken down and absorbed into the bloodstream.

7. The horse’s large intestine contains active bacteria and yeast which helps break down their food and convert it to energy. This also results in gas and what people call “gut grumbles”.

• This sound is a good thing because it indicates that the food is moving through the digestive system properly. An absence of this sound usually means digestive upset or possibly an obstruction.

8. For normal digestive tract activity for horses, they require a minimum of 1.5% of their body weight daily of roughage. That is roughly 15 pounds a day for a 1,000 lb. horse.

9. A normal start-to-finish digestive process – “End to End”– for a horse should take about 36-72 hours. That’s because a horse’s digestive tract from mouth to tail is about 115 feet long.

Your horse’s digestive system will function well under normal conditions.  However, as we all know, a horse’s gut can become sensitive to any sudden changes in diet.  So, if you are changing feed, hay, or adding treats, please do so slowly.

Allow your horse’s digestive system to process the changes and adapt naturally.

Keeping the microflora in your horse’s gut happy can be difficult if your horse is stressed, traveling long distances, sick, injured, receiving certain medications, weaning a foal, or being fed large amounts of grain.

So, it is really important we treat our horse’s digestive system with care and monitor their diets and their general health at all times.  It’s good to try to feed your horse as close to their natural grazing habits as possible.  And small frequent meals will greatly reduce the risk of digestive system disorders.

We want our horses to be happy and healthy, so we need to think about how what we feed our horses affects their natural digestive process.

Until next week, I hope you have a great weekend, and Happy Horses!