What do I need to know about my horse’s digestive system?
Lots. Of course there are entire encyclopedias of things to know about your horse’s digestive system, but for most of us the basics are a good place to start. More importantly is to know what is normal and what is abnormal in your horse so that you can be alerted to potential problems early on. And there is a lot about the outside of your horse that can tell you about the inside of your horse.
Let’s start at the input end and move towards the output end. In the process, learn about some of the problems that these digestive system parts can have and how you can spot these problems.
- Mouth - Where is all begins. Salivary glands, teeth, tongue and chewing start the process. Your horse can produce about 10 gallons of saliva a day. As your horse’s care taker and groom, notice how he eats and drinks. Not just the volume, the frequency as well. Dental issues can be indicated by dropping food, his breath smelling like rotten garbage, and maybe even head tossing and avoiding the bit.
Where it all begins.
- Pharynx - Where the respiratory system and the digestive system meet. Food travels though the pharynx into the esophagus. The soft palate acts as a one way valve here, so food doesn’t go into the lungs, and can’t come back to the mouth from the esophagus. This is one reason horses can’t vomit.
- From there, your horse’s feed enters the esophagus, which is basically a giant muscular tube that connects the pharynx to the stomach. The esophagus is the location for food to become stuck, causing choke. You might be able to see a knot in his neck, or he will ignore food and water and possibly have nasal and oral discharge. This is a Veterinary emergency! More on choke here.
- The stomach and the small intestine comprise the foregut. This is where digestion starts. Hydrochloric acid and enzymes are added to your horse’s meal in the stomach to start breaking everything down. The small intestine is where the majority of the nutrient absorption occurs. The small intestine also adds some of it’s own secretions to further the digestive process. In the stomach, many horses are susceptible to gastric ulcers. Poor performance, reactions to the girth, and difficulty keeping weight are all signs. Learn more about ulcers here, as sometimes the signs are subtle!
The end result. "Memorizing" your horse's typical manure can alert you to digestive issues.
- Now your horse’s meal enters the hindgut - which is the cecum, the large colon, the small colon, and the rectum. Starting with the cecum, which is basically a blind sac with one opening. Everything that enters must also exit there. While your horse’s meal is in the cecum, it’s blended around and digested by the microbes that live there. These microbes break down the fiber of your horse’s meal, freeing up some more nutrients for your horse. The microbes in turn get a nice house to live in. The single opening of the cecum is a definite location for obstructions and blockages.
Know how to listen for your horse's gut sounds. Do this daily to memorize what's normal for him!
- The large and small colon is the place for water to be reabsorbed from the meal. This is also where waste materials are secreted into, basically forming manure. The length of the colon also has microbes that ferment the meal. Some digestive issues, such as diarrhea, can start here. This is also the location in which the microbial balance can become skewed from a number of reasons. Grain overload, too much pasture, fevers, infections, even parasites (to name a few) can all disrupt this balance. This results in a large number of microbes dying - and their breakdown releases endotoxins which can lead to a number of problems, including laminitis and colic.
It should be noted that at almost all of the parts of the horse’s digestive system, there is a chance of colic - from nose to tail! The length of the digestive system of about 100 feet - lots of room for twists and kinks. Know the signs of colic - even really mild signs - and call the Veterinarian. Also be knowledgable about handgut acidosis and ulcers, which can impact your horse’s health and performance.
Finally your horse’s meal (now manure) is passed through the rectum and anus where it waits for you to scoop it up.
Clearly this is not normal - diarrhea is a major problem and can cause other horrible things, like dehydration. It can also be contagious (think Potomac Horse Fever, salmonella, etc.)
The best thing you can do for your horse is to notice and memorize his routine. His eating and drinking habits, his manure and urine output, and his behavior can speak volumes about what is going on inside. Always involve your Veterinarian in your horse’s health, even if you think it’s something totally minor.