By Emma Hardy, PhD
Gastric ulcers remain a common condition facing competition horses. This poses an ongoing and persistent challenge to trainers who face the negative effects of ulcers in terms of training and performance. To address the issue, the typical trainer spends a small fortune on scores of omeprazole and other ulcer remedies, only to find the problem isn’t resolved or simply comes back.
Meanwhile, researchers have been testing the very notion of “what is an ulcer?” The data casts doubt on whether go-to treatment approaches will actually work. A look at what the research now tells us about equine gastric ulcers may provide some new guidance for how best to address this nearly ubiquitous concern.
The two faces of gastric ulceration
While many people think of gastric ulcers as one specific disease, equine vets and researchers refer to gastric ulcers as a “syndrome” (Equine Gastric Ulcer Syndrome, or EGUS). The medical definition of a syndrome describes a set of symptoms and signs that together represent a disease process. In practical terms, this means that ulcers are really a clinical signs—truly a symptom—of underlying disease conditions.
A few years ago, articles began to appear in the scientific press highlighting differences in the healing of ulcers in two distinct regions of the stomach—the upper “squamous” area on the one hand, as compared to the lower “glandular” portion on the other. In recent years, researchers in Australia published a series of articles (Sykes et al, 2014) to “clarify the distinction between diseases in different regions of the stomach” (i.e., to describe the differences between ulcers in the squamous area of the stomach from those in the lower glandular area). The articles described significant differences between the two conditions, including prevalence, risk factors and response to treatment.
Squamous gastric ulceration
The upper region of the stomach is minimally protected from the corrosive effects of stomach acids. As such, squamous gastric ulceration (i.e., ulcers in the upper region of the stomach) is believed to result from the increased exposure to acid and other contents of the stomach. Ulcers in the squamous region are also more common, affecting upwards of 70% of Thoroughbred racehorses, as demonstrated in multiple studies over the past 20 years.
Glandular gastric ulceration
By contrast, ulcers in the lower glandular region of the stomach are believed to arise from a different set of conditions. The lower portion of the stomach is composed of numerous cell types including those that secrete gastric acid. Because horses secrete stomach acid continuously, the mucosal lining in this lower portion of the stomach is in direct contact with stomach acid at all times.
The lower portion of the stomach is also better protected—the glandular mucosa is lined with a thick layer of mucus that offers natural protection from acid. It is believed that glandular ulceration results from the breakdown of this protective lining. Although no research has conclusively shown exactly how this defence mechanism breaks down in horses, research in humans shows NSAID (non-steroidal anti-inflammatory drugs) use and bacterial agents are contributors.
Based on this, equine squamous gastric ulceration (ESGUS) is a specific condition distinct from equine glandular gastric ulceration (EGGUS).
Beyond the stomach….
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