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Equine Gastric Ulcer Syndrome – What Horse Owners Need to Know



Dennis H. Sigler, Ph.D.

Equine Gastric Ulcer Syndrome (EGUS) is a concern to many horse owners as it affects many of our performance horses.  Earlier research has reported that 93% of race horses, 60% of other performance horses and even 57% of all foals are affected by EGUS.  With such a high percentage of horses potentially affected, owners and trainers should be aware of some of the facts surrounding this ailment.

EGUS is described as tissue damage to the epithelial lining of the stomach, most commonly in the squamous mucosa area of the upper portion of the stomach.  However, it can also can occur in the lower glandular portion.  EGUS appears to be related to repeated acid exposure or a loss of the protective mechanism of the epithelial lining in which the gastric acids cause inhibition of cellular Na- transport, followed by cell swelling and eventual ulceration.  The apparent irritation and inflammation can lead to many observed symptoms in horses.  These include:  an overall “sour” attitude; poor hair coat; mild signs of colic; grinding of teeth; and overall decrease in level of performance.  The only sure diagnosis of gastric ulcers, however, are through endoscopy by an experienced veterinarian familiar with the syndrome.  EGUS is classified by Grades of 0 (no apparent damage or lesions) to a Grade 4 (extensive ulcers with areas of deep submucosal penetration).  Most confirmed ulcers fall in the Grade 2 to 3 categories.  The only FDA-approved pharmaceutical treatment for ulcers in horses is with the drug Omeprazole (GastroGardR or UlcerGardR).

Research has demonstrated that numerous factors related to stress can lead to horses showing symptoms of EGUS.  Basically, any change in environment, such as stall confinement, hauling, exercise, training and even type of diet have all been shown to contribute to this ailment.  Obviously, these happen to be all the things we subject our performance horses and prospects to just about every day!  In conducting over 4 years of research at Texas A&M on this subject, it was surprising to find a significant number of ulcers in yearling horses which were not in what would normally be considered high-stress situations.  The good news is that if we correct some of the factors that cause the stress for a particular horse, ulcers can and will heal spontaneously.  Some researchers and practitioners have suggested that simply turning horses out to pasture for a while can be beneficial to the healing process.  Research by the author and others showed that indeed, changes in environment which reduced stress to a certain group of horses could help reduce ulcer severity scores.  In one project, however, when yearlings were managed in small groups in paddocks and then brought in twice/day and fed in individual feeding stalls but then later moved to a pasture situation where they were group fed, average ulcer scores actually went up.  For some of these horses, apparently, this was a high-stress situation when they had to go back to competing for their food!  So, the moral of the story is – any situation which might cause stress to a particular horse may contribute to EGUS.

Type of diet also has been demonstrated, by research, to affect EGUS in horses.  High-grain diets have been shown to increase the incidence of ulcers in some horses.  However, it is sometimes hard to separate the effects of an added-grain diet from other factors such as confinement and training.

Feeding of alfalfa hay versus grass hay in a grain/hay diet has been demonstrated by several researchers to significantly decrease the severity of EGUS.  It is still undecided exactly what the mechanism for this effect might be, although it is probably related to the combination of the high protein and the higher level of Ca and possibly the chemical structure of the Ca in the alfalfa, not just the higher Ca level alone.  One research project by the author and others, which simply added a higher level of Ca-carbonate to a grain/grass hay diet to make it equal to the level of Ca in grain/alfalfa hay diet was not effective in reducing ulcer severity scores in yearlings.  Another research report showed a possible relationship to the form of trace mineral supplementation (using a zinc-amino acid complex) to improving ulcer scores in yearling horses.  More recently, a specialized Ca source derived from fossilized seaweed has been reported to help stabilize the acid in the stomachs of several species of animals and in one report, demonstrated a reduction in ulcer scores in a group of horses.

Without a doubt, certain diets can help manage horses which are prone to stomach ulcers.  It is recommended that for horses which show symptoms or have been diagnosed with ulcers, that they be fed alfalfa hay as opposed to grass hay.  Some of the positive effects of certain Ca sources and trace mineral supplements might also be considered.  According to some research reports, reducing total starch intake might also be beneficial.  However, it should be pointed out, that all stress-related management factors should be carefully evaluated if owners and trainers truly want to reduce the incidence of ulcers in their horses.  In some cases, medical treatment by a veterinarian may be the only choice to providing relief so that the horse is healthy, happy and can perform up to their potential in whatever event or use they are targeted for.

Dr. Dennis H. Sigler is a retired Professor and Equine Research Scientist, Texas A&M University. He has conducted research projects and published numerous scientific research papers in areas of horse nutrition, exercise physiology and management.  He has a lifetime of practical horse experience and trains and shows horses professionally.  He is also an approved AQHA and NRCHA judge.  Dr. Sigler currently is an Equine Nutrition Specialist for Martindale Feed Mill in Valley View, Texas and serves as a nutritional consultant for other commercial feed companies and individual horse farms.