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The Way of Horses: Your Horse Has Bugs!

By Eleanor Blazer

0Your horse has bugs! I’m not trying to be rude, just factual. Your horse has bugs! Your horse is a non-ruminant herbivore. In simple terms this means he eats plants and does not have multiple stomachs (a rumen) like a cow or sheep. But, he does have a cecum.

The cecum is part of the large intestine or hindgut. It is a fermentation vat and contains billions of bacteria and protozoa. These “bugs” break down insoluble carbohydrates (fiber) and allow the horse to derive energy from a food source that would otherwise be indigestible. Soluble carbohydrates (starches and sugars) must be digested in the small intestine. Grains and most commercially manufactured feeds are high in soluble carbs. If a horse consumes too much feed containing soluble carbohydrates the feed can get pushed through the small intestine and into the cecum.

When the high starch and sugar meal arrives in the cecum the beneficial bacteria and protozoa go crazy. The unnatural rapid fermentation process produces lactic acid. Lactic acid lowers the pH in the hindgut and creates an acidic environment (cecal acidosis). This in turn kills the good “bugs” and may lead to the release of endotoxins (poison) into the blood. These endotoxins can cause colic or laminitis.

There are several situations that can create an acidic environment in the cecum in addition to overfeeding grains that contain soluble carbs:

1.   Rapid Feed Changes

The bacteria and protozoa in the cecum must be given time to adjust when a feed change is being implemented. It takes about three weeks for the microbial population to be totally adjusted to the new feed and digesting at maximum potential. Always make feed changes slowly and over a period of at least 14 days. Many horse caretakers are aware of making the switch slowly when changing grain or concentrates, but the same thing must be done when introducing new hay. Whether it is a new load of hay from a supplier, from a different field or new hay for the season, it should be mixed with the hay the horse has been eating.

2.   Green Grass

Even though horses are designed to eat forage and are happier when in a large field of grass, too much of a good thing can make them sick. When introducing a horse to pasture it must be done slowly. The green forage can disrupt the microbial balance in the cecum. A horse used to a dry hay diet will have problems when suddenly turned out on pasture. Spring grass and fall grass after heavy rains are hi gh in soluble sugars. Horses must be gradually introduced to this type of forage. Some horses may have to be limited on the time allowed to graze or may not be able to tolerate the lush new growth at all.

3.   Treats

If you decide to give your horse treats keep in mind many of them contain large amounts of sugar or the ingredients may be high in soluble carbohydrates and starch. It is possible your horse is receiving large amounts of sugar in his diet due to the number of treats he is eating. If someone gives him a treat every time they walk by his stall and he knickers, problems may occur.

4. Antibiotics and De-worming Products

If your horse is on an antibiotic or has been de-wormed, some of the microbial population may have been killed. A probiotic may help restore the cecum to its natural healthy balance of bacteria and protozoa. Probiotics are products which contain living microorganisms, live yeast cultures and enzymes. Be sure the product was not stored in the sun and is fresh. (Brewers yeast is killed yeast, so will not aid the population of bugs.) There is some skepticism about whether the probiotic products survive the acid in the stomach and the digestive enzymes in the small intestine, but many proponents of the products believe they do work. One thing is for sure – they don’t hurt; any not utilized will be washed out of the system.

Other possible problems within the cecum are caused by stress, moldy feed or hay, reactions to vaccinations, sickness and poor quality water. Anything that adversely affects the horse in any way may also upset the delicate bacterial balance of the cecum. So, don’t grab the bug spray. Be nice to the good bugs and try to keep them healthy and happy – your horse will be “buggy about you.”


* Proper nutrition and management practices can prevent many problems associated with caring for horses. You can learn how to provide your horse with a better life-style by taking the online course “How to Feed for Maximum Performance” taught by Eleanor Blazer. Go to www.horsecoursesonline.com for more information. Make sure to ask for the CHA member discount on these courses!