As a conscientious horse owner you would never intentionally set your horse up for ulcers but today's diet, training schedules and eating behavior have been shown to increase your horse's susceptibility to Equine Gastric Ulcer Syndrome (EGUS).
The glandular portion of the equine stomach represents the lower two-thirds of the inside surface, while the non-glandular portions covers the upper one-third. Many ulcer problems are developed in the non-glandular squamous mucosa portion due to the lack of protection against the strong acid produced in the lower region. Normally a horse is a perpetual grazing machine and therefore continuously secretes digestive acids. So longs as the horse is grazing, the forage absorbs a lot of the secretions and protects the tender, squamous mucosa from acid. In addition, equine saliva contains acid neutralizing bicarbonates and protective mucins.
The type of food a horse consumes and the period of time over which the stomach remains empty appears to play an important role in determining whether ulcers will or will not develop. Research has shown horses turned into stall confinement after they have been kept free-ranging in the pastures, develop lesions in the stomach within a week even though they have free-choice hay.
Another factor involves the feeding of grain along with the hay to stalled horses. Since grains (oats and cracked corn) contain a higher level of calories, much of the horse's energy is obtained from the grain. This leads to the rejection of the hay even when it is offered on a free-choice basis. This creates a situation where the horse frequently has an empty stomach. Moreover a high grain diets produces greater acidity than a low grain diets and alfalfa causes lower acidity than grass hay. Thus, there is an increased susceptibility to the eroding, irritating action of hydrochloric acid continually being secreted.
The events leading to gastric ulceration reflect the interactions between acid secretion and a reduction in the defense mechanisms of the gastric mucosa.
It is estimated nearly 90% of thoroughbreds in training have stomach lesions and about 40% of them have full-blown ulcers. Why are the percentages so high? It seems thoroughbreds in training are more prone to stomach lesions and ulcers. It is thought that exercise in and of itself, increases the intra abdominal pressure inside the stomach which allow the ever present acid to be pushed up irritating the sensitive upper non-glandular area. (Lorenzo-Figueras and Merritt) Apparently gastric pressure sharply increases as a horse moves at any gait faster than a walk. Research measuring pH near the opening of the esophagus during exercise support this hypothesis.
Moreover while the equine gastric ulcer syndrome is well known to be a problem for racing horses the affliction is high for other performance horses as well. Michael J. Murray, DVM, points out that 30 to 40 % of all dressage horses may also be bothered with EGUS.
The two main groups of drugs used in treating equine stomach ulcers are acid suppressant drugs and mucosal protective drugs. The use of acid suppressant drugs is more prevalent. Omeprazole, for example, acts by blocking the enzymes involved in the final stages of acid secretion while other acid suppressants, such as Ranitidine, act by blocking specific receptors related to acid production.
Omega-3 essential fatty acids derivatives are known as prostaglandins from the E series. These "good prostaglandins" modulate hydrochloric acid secretion, increase bicarbonate and mucus production in the stomach mucosa and enhance mucosal blood flow. They can even reduce the incidence and extent of ulcers as is shown in animal research from several universities in the US, Europe and Middle East and they may represent an important defense mechanism in preventing and managing stomach ulcers.
Stomach ulcers are painful. The high prevalence of this affliction among thoroughbreds warrants finding preventive measures to alleviate this problem. Dietary factors play an important role in the development of stomach lesions. Acid suppressant and mucuosal protective drugs are of great help, however, it may also be beneficial to try a more preventive approach using omega-3 fatty acids daily. The long- chain n-3 fatty acids found especially in marine oil can serve as potent building blocks for good and protective prostaglandin molecules.