Southern Pines Equine Associates

Case of the Month Case Report:
Gastric Ulcers in the Adult Horse

Author: Dr. Phil Woods DVM, Ph.D., Dip ACVIM

The topic of equine gastric ulcer syndrome (EGUS) is one of those "hot" topics in equine medicine, and has led to significant benefits for the health of the horse while posing as many questions as answers! While population studies have shown some startling results, for example in comparing EGUS in racehorses and pleasure horses for example, the significance of gastric ulcers in the individual horse can be difficult to evaluate.

Causes: EGUS is associated with all the things that cause ulcers in humans including psychological and physical stressors (e.g. race training, long distance transportation, un-natural housing conditions, surgery), medications (e.g. anti-inflammatory drugs such as phenylbutazone and corticosteroids), and underlying diseases (e.g. pleuropneumonia, lameness). There is no strong support at this time for an infectious agent such as Helicobacter pylori being associated with EGUS. It has always impressed me that this is an equine disease caused by humans!

The numbers: Epidemiologic studies of different populations of horses has been very useful in identifying factors that predispose to formation of gastric ulcers. If one compares racehorses to pleasure horses, up to 80% of racehorses in active training may have gastric ulcers while only 35% of pleasure horses will have similar endoscopic findings. Horses that are held off feed or are fed intermittently appear to have a higher prevalence of gastric ulcers. The accumulated research highlights the role of multiple management factors associated with EGUS.

The client's presenting complaint: The world is your oyster; there is such a wide spectrum of presenting complaints that nothing surprises me any more! Chronic colic, poor performance, poor body condition, poor appetite, and behavior changes are the most commonly identified complaints that horses are presented to us for. All of these are valid client complaints and the clinical signs may refer directly to EGUS, or, may refer to a primary disease condition with EGUS as a secondary consequence. The most common complaint that horses are presented to us at SPEA is that of poor performance.

The diagnosis: It is necessary to perform an endoscopic examination of the stomach to physically identify that ulcers are present. I know of no other practical way to definitively diagnose ulcers in the stomach. The endoscope needs to be at least 2m long, and preferably 3m long. At SPEA we use a 3m endoscope because the majority of horses examined are large warmblood types. Our endoscope is a video-endoscope, and produces an image on a television screen that is viewed by the clinician and client as it is seen in the stomach, and can be stored on video-tape for further analysis.

We have to prepare the horse for evaluation in two ways: 1) The horse needs to be starved for 18 hours and held off water for 2-3 hours prior to endoscopy. This is essential to produce maximum emptying of the stomach to allow examination of all the internal surface of the stomach. 2) Just prior to the procedure, the horse is heavily sedated to allow easy and safety of passage of the scope in to the stomach, and to allow inflation of the stomach to maximize visualization of the internal surface of the stomach. When we have the scope in the stomach, we may have to remove excess gastric juices using a suction device in the scope.

The result: The video-endoscope produces a picture of the inside of the stomach. From the interpretation of that image we can make statements about the health of the stomach, and in particular about the grade or degree of ulceration and the anatomic location of the ulcerated areas. The clinical significance of the interpretation depends upon the severity of ulcers and their anatomic location. When we analyze our results at SPEA, we find that most of the horses we scope, after excluding other clinical problems, have some degree of EGUS, but that most of the horses have mild, grade 1-2 type ulcers, located at the junction of squamous mucosa and glandular mucosa, particularly around the lesser curvature of the stomach.

Treatment: Horses with EGUS are treated in a very similar way to that of humans with gastric ulcers; 1)medications 2)environmental management.

1) Medications: There are many medications touted for use in the treatment of EGUS, however, in my opinion, only 2 are practical and truly effective in the horse, and I will only dwell upon these two. The 2 drugs are ranitidine (Zantac) and omeprazole (Gastroguard (known as Prilosec in humans)). Both of these drugs inhibit secretion of acid in the stomach, and omeprazole is probably the more effective at the job. However... "the sting in the tail" is that omeprazole is about 5 times as expensive as ranitidine, with one month's treatment costing about $1200 for omeprazole and $200-250 for ranitidine.

So which of the 2 medications should be chosen when treating EGUS in your horse. My guidelines are to medicate according to 1) ulcer severity, 2) current and proposed use of the horse, i.e. stress level, and 3) cost constraints. Therapy is also separated out in to resolution of ulcers and maintenance of an ulcer-free stomach. In my ideal world all horses with EGUS would be medicated with omeprazole, it is plainly the better of the 2 medications. However if the horse is not in heavy training for a big event, then the use of ranitidine is perfectly acceptable and much more economic. As a horse moves in to full competition it is of value to consider omeprazole during transportation and during competition.

2) Management: One area of EGUS that has not been well defined is that of management of affected horses. Does one keep the horse on anti-ulcer medications for ever, or can one alter its environment to reduce the various stressors that are thought to trigger EGUS? We know very little about this area of disease control, but common sense should tell us that improving the horse's environment, and altering diet and training methods will help reduce stress. Certainly some horses may need fairly continuous medication, and we know that this can be done at a lower level that that required for initial resolution of the ulcers.

Expectations: So what should you expect subsequent to therapy, and how do you measure success? Certainly a repeat scoping will tell you whether or not the ulcers have gone away. However, my major measure of success is the subsequent performance of the horse, given that most of the horses we scope are event and racehorses. The results we note are invariably quite dramatic, with the horse being more athletic, more focused and keen to compete, and showing a dramatic improvement in appetite and general demeanor. The real challenge that we have now is to keep this level of athleticism at its peak by various means. By collaborating with the veterinarian, the rider gains a new horse with considerable untapped potential.

e-mail Dr. Jim Hamilton, DVM
Southern Pines Equine Associates
Phone  910-692-8640      fax 910-692-1142
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