The Facts On Ulcers
by Beth Stelzleni of Mars Horsecare US, Inc.
Ulcers are a major problem in the horse industry today, and it has been reported that 60-95% of all mature working horses have ulcer problems. Horses most at risk for ulcers include performance horses - especially race horses, but leisure horses can be at risk for ulcers as well. Any horse, regardless of being a high level race horse or a weekend pleasure pony can develop ulcers if exposed to some of the risk factors we will discuss here.
To understand why the horse is so at risk for ulcers, it’s important that we understand the horse’s stomach anatomy. The horse’s stomach has two main regions. The first region is the non-glandular region, which takes up the top part of the horse’s stomach. This region is made up of very sensitive tissue, similar to the type of tissue that makes up our esophagus. This region does not produce any acid and also does not have any protective factors against it. The lower region in the horse’s stomach is the glandular region, which has tissue that is much tougher than the non-glandular region. The glandular region does produce acid and has protective factors lining the tissue, such as mucus. It’s important to note that the horse’s stomach produces acid at all times, even if there is not food in the stomach. This means that if the horse’s stomach is empty at any time, some of this unused stomach acid will start to eat away at the sensitive non-glandular tissue. Because the non-glandular region is the more sensitive of the two regions, the majority of stomach ulcers in horses occur in this upper region.
Hard physical work also contributes to ulcer formation in horses. As a horse works, the muscles in the horse’s body put pressure on the stomach. This pressure pushes the acid that normally stays in the glandular portion of the stomach into the non-glandular portion, so it exposes that sensitive non-glandular tissue to acid. The harder a horse works, or the faster he goes, the more pressure is put on the stomach, so more acid is pushed into the sensitive non-glandular region. Diets that are high in NSC (or sugar and starch) contribute another factor that increase the risk for ulcers. The bacteria in the stomach ferment the NSC when it enters the stomach in high amounts. When this fermentation occurs, acid byproducts called volatile fatty acids are produced which increase the acidity of the stomach. So on top of the normal stomach acid that’s already in the stomach, diets high in NSC contribute to the acidic environment by producing high quantities of VFA’s.
One of the major management factors we see today that may increase the risk of ulcers is a horse’s change from their natural setting to a very unnatural one. In its natural setting, a horse is on pasture all the time and can eat 24 hours/day if they wish. This continuous eating means that there is always something in the stomach for the acid to work on, and this food that’s always in the stomach serves as a protective factor for the sensitive non-glandular portion. Also, the constant chewing that comes with grazing means that there is constant saliva production. Saliva is a very important buffer for the horse and plays a big part in protecting against ulcers. In today’s setting however, most horses are stalled for all or at least part of the day. The problem with stalling horses isn’t necessarily the actual containment; it’s the meal-feeding that goes along with stalling a horse. Meals create periods where the stomach is empty, so the acid that’s always in the stomach has nothing to work on. Periods of time without food also mean the horse isn’t chewing, so there’s no saliva production as well.
If you have a horse who is at risk for ulcers or has had ulcers in the past, there are a few simple steps you can take to reduce the ulcer problem. The first rule of thumb is to keep a routine, and this should be the rule of thumb to use with any horse. Horses are routine animals, and keeping a constant routine with them helps to manage stress. Turn-out, preferably with a buddy, is an excellent way to reduce the risk of ulcers because it increases the time spent with food in the horse’s stomach and the amount of saliva produced. It also helps to feed before exercise to give the stomach acid some material to work on besides actual stomach tissue. Once an ulcer case has occurred though, we need to treat it medically to heal the existing ulcer before we can start fresh with a healthy horse.
We also need to lower the NSC in the diet, since diets high in NSC can produce VFA’s in the horse’s stomach. For an easy keeper, you need to look for a grain that has a very low amount of starch but also a low amount of calories, such as a ration balancer. For a hard keeper, your best bet is a high fat grain mix to provide the calories the horse needs but still keep the starch levels low. It’s also a good idea to lower the total amount of grain in the diet, both to lower the amount of NSC and allow for the addition of more hay in the diet, as hay can give a horse bulk in his stomach and increase chew time (which also increases saliva production).
What grain is fed needs to be provided in small meals so that excess NSC cannot be fermented in the stomach and produce VFA’s. A good rule of thumb is to make sure that grain meals do not exceed 0.5% of the horse’s bodyweight per meal. This means that a 1000 lb horse should have grain meals no larger than 5 lb. It’s also a good idea to offer free choice hay, as we’ve talked about how allowing your horse to eat continuously throughout the day keeps the stomach from being empty and allows for good saliva production. Studies have shown that including alfalfa in the diet is an excellent idea for ulcer prone horses, as the high calcium and protein in alfalfa hay buffers the stomach and helps control any excess acidity. The alfalfa doesn’t have to be fed in high levels either. We’ve seen evidence that levels as low as 1 lb of alfalfa per day can have a beneficial effect on ulcer development.
