What do we really know about equine gastric ulcers? For horse caretakers and their veterinarians, gastric ulcers are all too familiar, yet not very well understood. Recent research has revealed they’re more complicated than they seem.
Gastric ulcers are very common, especially among performance horses. As riders and trainers, we know that gastric ulcers – and gut health in general – significantly impact our horses’ training and performance, behavior and attitude, and overall health and well-being. So it is in our best interests to learn as much as possible about equine gastric ulcers.
What are gastric ulcers…really?
Gastric ulcers are simply lesions (damaged areas) on the inside surface of the stomach.
Technically speaking, this condition is more accurately described as “Equine Gastric Ulcer Syndrome” or EGUS. The key word is “syndrome”– in this case, a set of health issues that cause stomach lesions. Put another way, ulcers themselves are really a symptom of an underlying pathology. It’s this underlying disease that remains more of a mystery.
Different types of equine gastric ulcers
For years, it was widely believed that stomach acid, which is constantly present in the horse’s stomach, causes gastric ulcers. More recently, the scientific community has learned that this perspective may be too simplistic.
The horse’s stomach is divided into two regions. The lower two-thirds is known as the “glandular” region (after the glands that exist there to secrete acid and enzymes for digestion). The glandular region of the stomach is coated with a thick layer of mucus that protects it from stomach acid. The upper one-third, called the “squamous” region, is less protected. The two sections of the stomach are divided by a visible line called the margo plicatus, and it’s here that ulcers are often found.
Although ulcers are more common in the upper squamous portion of the stomach, they do also appear in the lower glandular region. Research published in the last few years proves that ulcers in these two regions are different and reflect different disease processes. In light of this, an article published in the Journal of Veterinary Internal Medicine (Sykes, et al, 2015) proposed different nomenclature — Equine Squamous Gastric Disease (ESGD) and Equine Glandular Gastric Disease (EGGD) – to recognize them as two distinct and different conditions.
While we lack a complete understanding of the true cause of gastric ulcers in horses, it is widely accepted that horses used in performance face a significantly higher risk of developing the condition. (see photo) Research shows that competition and training aren’t necessarily factors in the development of ulcers. Horses that travel and are kept in stalls, and are intermittently fed diets rich in grain and/or with limited access to forage, are more likely to suffer from gastric ulcers.
Gastric or colonic ulcers
Keep in mind that horses can suffer from ulcers in the colon as well as in the stomach. This condition is not limited to Right Dorsal Colitis, commonly associated with the use of non-steroidal anti-inflammatory drugs (NSAIDs like phenylbutazone, commonly known as Bute). In the last ten to 15 years, researchers have found ulcers in all sections of the equine colon.
Even with a definitive diagnosis of gastric ulcers, veterinarians cannot rule out the possibility that a horse also has colonic ulcers. Research shows that gastric and colonic ulcers frequently go hand-in-hand. One study (Pellegrini, 2005) published in the Journal of Equine Veterinary Science, found that 54% of horses had both gastric and colonic ulcers. Further, the symptoms of colonic ulcers are often the same as those associated with gastric ulcers.
Diagnosing gastric ulcers
In practice, many horse caretakers and their veterinarians rely on clinical signs or symptoms for diagnosing gastric ulcers. These include poor appetite, dull coat, wind-sucking or cribbing, lack of energy and/or decreased performance, irritability, listlessness or other changes in attitude, and poor body condition. The problem with using symptoms to guide a diagnosis is their vague nature; many can be associated with other conditions. Some horses show no clear symptoms at all. Further, there is no distinction between the clinical signs for squamous and glandular gastric ulcers.
The only sure way to diagnose gastric ulcers is to visually identify them, which veterinarians can do through the use of a 3m gastric endoscope. Though gastroscopy is fairly reliable, it’s certainly not perfect. It’s also somewhat invasive, requiring up to 12 hours of fasting, a withdrawal of water for four hours, and sedation during the procedure.
Treatment for gastric ulcers
Determining the best course of treatment for horses with ulcers depends on a clear diagnosis. Recent research shows that squamous ulceration and glandular ulcers require entirely different treatment approaches.
- For squamous ulcers, the generally accepted therapy is to suppress acid production in the stomach. In conventional medicine, this is accomplished through the use of pharmaceuticals, including proton pump inhibitors such as omeprazole, or H2 antihistamines like ranitidine or cimetidine. Omeprazole, in the form marketed commercially as GastroGard®, is the only product approved by both Health Canada and the FDA in the United States for treating equine gastric ulcers.
- Horses diagnosed with glandular ulcers have fewer clear treatment options. Research published in 2014 in Equine Veterinary Journal (Sykes, et al, 2014) showed that ulcers in the glandular portion of the stomach did not respond as well to treatment with omeprazole as ulcers in the squamous portion. In their 2015 article in the Journal of Veterinary Internal Medicine, Sykes and others proposed that bacteria may play a role in the development of glandular ulceration, but the effective use of antimicrobials in treatment lacks evidence at this point. Currently, protection of the glandular mucosa with the use of sucralfate, in conjunction with omeprazole administration, is the most widely accepted course of action.
Prevention may be the best approach
As is often the case, prevention may be the best approach to gastric ulcers. By minimizing the risk factors associated with ulceration, caretakers give their horses the best chance of avoiding the problem in the first place. Changes to your feed and management program may benefit your horse’s digestive health and minimize ulcer risk. These include:
- Providing maximum turnout
- Offering free access to forage (quality hay or grass) and using a hay net or slow feeder
- Feeding a low starch/low carbohydrate diet
- Offering multiple small meals throughout the day
- Adding chaff or soaked beet pulp to the feed to increase chewing and slow intake
- Adding oil as a fat source for horses with higher caloric needs
It may also be useful to supplement your horse’s diet with nutritional support for digestive tract health. This includes nutrients to help strengthen and preserve the integrity of the gut wall (stomach and hindgut), feed beneficial bacteria and other digestive flora (prebiotics), and enhance immune health. Changes to your feed and management program may benefit your horse’s digestive health and minimize ulcer risk.
While gastric ulcers are a common and recognized condition in horses, it seems the more we learn about them, the more our beliefs are challenged. Much remains to be studied before we truly understand this issue. In the meantime, taking steps to mitigate the risks of ulcers may be the best you can do to protect your horse.
Dr. Natalie Cooper is a graduate of Louisiana State University’s School of Veterinary Medicine. She was a Veterinary Medical Officer with the USDA where she was responsible for oversight regarding the welfare needs of agricultural animals used in research settings. She currently co-owns a mixed animal practice in central Arkansas and oversees veterinary education and research endeavors for Freedom Health LLC as the VP of Veterinary Medicine; she joined the company team in 2016. In her free time, Natalie enjoys riding and showing her reining horse.