Gastric ulcers explained
A change in behaviour may be a sign that your horse has developed a gastric ulcer. Vet Leona Bramall explains how ulcers develop and how a combination of drug treatment and management changes can help
EVER MORE PEOPLE are becoming aware of equine gastric ulcer syndrome (EGUS). Traditionally, EGUS was seen as a condition that affected racehorses and, while racehorses undoubtedly continue to show the highest incidence (over 80% of horses in training), vets are seeing increasing numbers of companion horses and ponies (up to 60%) diagnosed with the condition.
So how are ulcers created, what effect do they have on horses and how can they be treated and prevented?
Gastric anatomy
From an ulcer perspective, the stomach has two main regions — the non-glandular/ squamous mucosa that occupies the top portion, and the glandular mucosa that occupies the bottom section and exit (pyloric region). The non-glandular region, as the name suggests, is devoid of glands and, in turn, this means that it doesn’t produce gastric acid or a protective lining of mucus. The glandular region contains glands that produce both gastric acid and mucus which protects the cells from gastric acid injury. The two regions are easily distinguishable and the line defining the two is referred to as the margo plicatus. Gastric ulcers can develop in one or both regions of the stomach and the presence/ absence in one region doesn’t necessarily mean the presence/absence in the other. While squamous ulcers can occur throughout the non-glandular mucosa, the most commonly affected region is the non-glandular area just above the margo plicatus. Similarly, glandular ulcers can theoretically occur anywhere in the glandular mucosa, but by far the most common location is in the pylorus (see picture, below right). Squamous/non-glandular ulceration can occur as a primary condition or secondary to delayed gastric emptying. Primary squamous ulceration is much more common and occurs as a result of acid damage to the non-glandular lining. Risk factors include intense exercise, high concentrate/low forage diets, starvation, water restriction and over-supplementation with electrolytes to name but a few. Glandular ulceration is believed to occur secondary to a breakdown of the ‘normal’ mucus defence mechanism protecting the mucosal lining. The cause of this is unclear and further studies are required.
There is currently no consistent link between Helicobacter pylori (implicated in human peptic ulcer disease) and equine gastric ulcer syndrome.
Diagnosis
Gastroscopy (stomach endoscopy) remains the only way to definitively diagnose gastric ulceration. Horses displaying clinical signs should be examined by a vet. To do this, food needs to be withheld for 18 hours so that the stomach is empty for the examination. Some horses require a longer period of starvation if the stomach has insufficiently emptied before the procedure. During the gastroscopy, it’s important that both stomach regions are visualised because, as already mentioned, the presence of squamous ulceration doesn’t preclude the presence of glandular ulceration and vice versa.