Ask the Vet
with Ben Buchanan, DVM, DACVIM, DACVECC
Ulcers in Performance Equine Athletes
A ll great athletes are subject to stress, and the horse is no exception. The horse has a unique stomach with two very different parts. One half is like our stomach and has glandular tissue and produces hydrochloric acid. This part of the stomach also produces mucus and other surface products that protect the tissue from acid damage. The other half is the same squamous tissue as the esophagus and has no glands and limited ability to protect itself from acid exposure. The acid exposure causing damage to the tissue is not just hydrochloric acid produced by the stomach, but also several weak acids produced by digestion and metabolism of the feed. These weak acids cause damage when the stomach pH is below 4. An example of this type of acid is vinegar (acetic acid). Apple cider vinegar should not be used to treat ulcers, but rather it is used experimentally to cause ulcers. When we are talking about gastric ulcers in horses 99% of the time we are referring to damage in the non-glandular squamous half. This development of gastric ulcers in this part of the stomach is a balance of aggressive and protective factors. Understanding this relationship allows us to manage the horse to promote the protective factors and limit the aggressive factors shifting the balance toward health. Signs of gastric ulcers are often non-specific and include: colic, grinding teeth, sore girth, sore back, poor performance, and behavior change. One common complaint in a horse with ulcers is the refusal to eat grain until after eating hay or alfalfa. To truly diagnose ulcers in the stomach, evaluating the stomach lining with an endoscope is required. In addition to the benefit of evaluating the squamous mucosa, a gastroscopy also allows us to evaluate the upper airway function, look for esophageal reflux,
parasite and bot larvae in the stomach, evaluate the gastric outflow and to evaluate the proximal small intestine and bile ducts. Because the primary damage is on the squamous tissue, the pain associated with gastric ulcers in horses is analogous to heart burn in people. Similarly, treatments to control the pain and heal the stomach are the same as treatments for heart burn in horses. Utilizing treatments for classic peptic ulcers in people (like antibiotics or aloe vera) are not going to be successful as it targets the wrong area of the horse stomach. The cornerstone of treatment are drugs that inhibit acid production. Currently Gastrogard ® is the only approved product that has been shown to heal ulcers in clinical trials. While the cost of this product can be expensive it is the only product with a manufacture guarantee to be effective. Other attempts to compound omeprazole (the main ingredient in Gastrogard) produce products with variable effectiveness and very short shelf lives. Use of buffering agents has also been utilized to combat the acid. While very effective, the horse stomach produces acid constantly and turns over every 2 hours. A full bottle of extra strength Maalox will stop the abdominal pain, but it will only last 2 hours. Other buffering agents have similar limitations and require frequent dosing. Coating and binding agents can help ulcers to heal once they develop, but do not reverse the acid production and do not prevent future ulcers from developing. A standard treatment for gastric ulcers is daily for 4 weeks. In some cases the ulcers will be healed before that time period and a gastroscopy at 2 weeks can monitor for improvement and potential resolution. Repeating gastroscopy to confirm resolution is important prior to stopping treatment. If a horse is eating well and not showing signs of colic, why worry about gastric ulcers.
When a horse is under saddle and exercising there is an increase in pressure on the stomach which pushes acid up onto the squamous tissue and into the esophagus. Horses with mild to moderate gastric ulcers may not show “classic” signs of gastric pain but may only show a performance limitation or agitation during exercise. They don’t typically lay down to complete a sleep cycle and may begin to show signs of fatigue when boarded at a show grounds. Treating these horses with Gastrogard ® improve performance. Once gastric ulcers have been identified and treated the conversation often shifts to prevention. Similarly to treatment, prevention focuses on shifting the balance between aggressive and protective factors. Lower doses of omeprazole can help provide periods of time with acid suppression and prevent ulcers from developing. Strategically treating horses with Gastrogard ® before transport and during a show can prevent ulcers from developing during competition. It is important to remember that gastric ulcers is a management induced problem and is very common. If a horse has been treated for gastric ulcers is put back into that environment the ulcers will develop again. Between 60% and 90% of horses in competition have gastric ulcers. Identifying them and treating them is one way to give you and your horses a leg up on the competition. For questions regarding ulcers in performance equine athletes, please feel free to call one of Brazos Valley Equine Hospitals locations or visit bveh.com.
e opinions of the authors are their own and do not necessarily reect those of the WPRA. Please refer to chapter 18 of the WPRA rulebook for all program or compliance questions.
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34 WPRA NEWS MARCH 2020
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