Heather Beach, DVM
In horses, we refer to the generalized syndrome of erosive and ulcerative lesions of the stomach as Equine Gastric Ulcer Syndrome or EGUS. In the last 15+ years since the 3 meter gastroscope has become readily available to practitioners, our understanding of this disease has improved considerably. In September 2015, the European College of Equine Internal Medicine published a consensus statement on gastric ulcers in horses. We now recognize that EGUS should be further classified into two distinct sub-syndromes Equine Squamous Gastric Disease (ESGD), and Equine Glandular Gastric Disease (EGGD). These two classifications help us to describe the exact anatomical location of the ulcerations, and require specific and distinct treatment and management protocols to ensure proper healing and prevention.
Equine Squamous Gastric Disease or ESGD
Equine squamous gastric disease (or ESGD) is the form of gastric ulcers that most people are familiar with. The stomach of the horse is anatomically unique -- the top portion is covered in a lighter squamous epithelium, while the bottom is composed of darker glandular portion. The cells lining the squamous portion of the equine stomach are similar to skin cells and the cells that line the esophagus. These squamous epithelial cells have no protection against the harsh pH of stomach acid, which typically pools lower in the glandular portion of the stomach. The cells in the glandular portion of the stomach secrete bicarbonate and mucous which offer protection against the harsh, acidic environment. When a horse exercises, the acid from the lower portion of the stomach splashes against the squamous epithelium and can cause ulcerations, frequently noted at the anatomical delineation between non-glandular and glandular portions of the stomach, known as the margo plicatus.
Treatment for Gastric Ulcers in the Horse (ESGD)
ESGD is treated by suppressing acid production in the horse for a minimum of 21-28 days. The best studied product for achieving acid suppression and healing of ulcerations is the medication ompeprazole, sold under the brand name of GastroGard. Near the end of the first month of treatment, a recheck gastroscopy is recommended to ensure the ulcerations have healed, because as many as 25% of horses may require longer than 28 days of treatment.
Equine Glandular Gastric Disease (EGDD)
EGGD differs from ESGD, in that it is believed to result from a breakdown of the normal defense mechanisms that protect the mucosa from acidic gastric contents, since this portion of the stomach is normally subjected to near constant exposure to acid. The factors that contribute to breakdown of this protective layer are yet to be clearly demonstrated in the horse, but in humans the bacteria Helicobacter pylori and the use of non-steroidal anti-inflammatory drugs (NSAIDs) are most common causes of gastric ulcers. To date there remains conflict in the literature as to the role of bacteria in EGGD. While the prolonged use of NSAID medications in horses such as Bute or Banamaine may play a role in causing EGGD, many horses who have not received these medications still suffer from this disease. It is likely that multiple different mechanisms contribute to the development of EGGD in the horse. Reduced access to water has been shown to increase the prevalence of both EGGD and ESGD in horses.
Treatment for Equine Glandular Gastric Disease (EGDD)
Treatment of EGGD is not as straightforward as treatment for ESGD. In most cases, omeprazole alone is not sufficient to heal EGGD ulcerations. Other medications utilized along with omeprazole to heal lesions in this region of the stomach include:
Misoprostol - this is a synthetic prostaglandin thought to help restore some of the body's natural defenses against acid by providing additional acid suppression, increased mucosal blood flow and increased bicarbonate secretion.
- Sucralfate - This is a medication that binds to the negatively charged particles in the ulcer bed, buffering acid by increasing bicarbonate secretion, stimulating prostaglandin production, and coating the ulcer bed. In the stomach, sucralfate is converted to a sticky amorphous mass, which is thought to prevent diffusion of acid into the ulcer.
SYMPTOMS OF GASTRIC ULCERS IN THE HORSE
Gastric ulcers in horses can lead to pain and discomfort, poor performance and colic. Symptoms of gastric ulcers vary and may include:
- Behavior changes: varying from crabbiness to explosiveness to nervousness
- Girthiness: or generalized reluctance to be groomed or touched
- Poor performance: symptoms may mimic or overlap with symptoms of back pain and include reluctance to lift through the back, difficulty cantering, sour attitude towards work
- Poor appetite: picky eating, bolting food then walking away from grain bucket
- Poor body condition/weight loss
- Chronic diarrhea
- Poor coat condition
- Grinding teeth
- Stereotypical behaviors: cribbing, weaving, stall walking
If your horse is showing symptoms of gastric ulcers, getting a definitive diagnosis through gastroscopy before and after treatment is the best way to ensure an accurate diagnosis and successful course of treatment.