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Identifying and Preventing Equine Gastric Ulcer Syndrome (EGUS)
This past April, we hosted our second annual Equine Event with support from Merial. Our guest speaker, Dr. Stephanie Thompson lectured on a range of topics from rabies, West Nile virus, gastric ulcers and intestinal parasites. The whole event was a great success, if I do say so myself. Some of you were lucky enough to be there and enjoy the tasty food and informative lectures. For the rest of you, let me say that you missed out! But don’t despair; I’m going review one of the larger topics that Dr. Thompson discussed – gastric ulcers.
Gastric ulcers are a vague concern for some horse owners and a real appreciable threat to others. What kind of horse comes to mind when you think ulcers? A high strung thoroughbred at the track or a backyard pony that trailers to a few local shows? In fact, both of those groups are susceptible. Up to 90% of racehorses and 60% of show horses are affected by gastric ulcers. And many of your non-performance horses (especially foals) can be affected as well. Think your horse may be at risk for Equine Gastric Ulcer Syndrome (EGUS)? Let’s find out.
First, what are the signs of gastric ulcers? They vary from obvious colic signs and bruxism (grinding the teeth) to weight loss, poor hair coat, decreased performance and poor appetite. The majority of adult horses display very subtle signs, if any, which can be overlooked by many owners, trainers, or veterinarians. In foals, signs include intermittent diarrhea, colic, poor growth, rough hair coat and pendulous abdomen. Clear clinical signs can help diagnosis some cases of ulcers, but when roughly 50% of affected horses show little to no clinical signs, you need further diagnostics to give you the whole picture.
But why do horses get ulcers? First, let me explain a little more about the equine stomach. A horse’s stomach is divided into two sections – glandular and non-glandular. The glandular bottom half secretes the stomach acid and has a protective layer to keep it from being damaged by that acid. The top non-glandular section is designed for mixing the stomach contents and does not have that protective layer. The line that separates the two sections is called the ‘margo plicatus’. Gastric ulcers are usually found just above the margo plicatus in the non-glandular section of the stomach.
The equine stomach is constantly secreting acid because horses were designed to graze throughout the day and thus continually ingest buffer (ie food) for that acid. Gastric ulcers are often called a man-made disease because most of us do the opposite of what nature intended. We feed our horses two or three set meals a day, leaving horses with periods of time where there is no food in the stomach. Without food to neutralize the stomach acid, the stomach lining experiences prolonged periods of acid exposure. As you can imagine, this can cause some irritation.
But it isn’t just about how we feed our horses. Training, shows, travel or any change in a horse’s routine can increase their stress level and cause gastric ulcers. Take that thoroughbred on the track. His high-intensity training, frequent travel and general lifestyle are almost designed to cause gastric ulcers. That’s almost a no-brainer. But what about that backyard pony that may do two or three shows a year? Her life is generally pretty stable – daily turnout, free-choice hay, riding lessons several times a week, nothing too exciting. Then, you take that little pony and trailer her to some show away from all of her friends. You mess up her feeding schedule, ride her more than usual and maybe keep her overnight at a strange new barn. Think that might stress her out? Yes! Her whole routine is off and that stress puts her at great risk for developing gastric ulcers.
Now, how many of you do similar things to your horses? Many of us do, and most of us wouldn’t think twice about causing ulcers. After all, it’s just for the weekend, right? But in many horses, a weekend of stress is all it takes to start causing gastric ulcers. There are also a number of predisposing factors that have been identified as contributing to EGUS including prolonged NSAID administration, highly fermentable carbohydrate grains, delayed gastric emptying, and yes, even exercise.
Now how do we diagnose these buggers? That is simple and yet, not always so easy. A presumptive diagnosis is often made based on clinical signs alone. But remember many horses show little or no signs! A definitive diagnosis is made via endoscopy. Horses must be fasted for 12-24 hours in order to sufficiently empty the stomach. They are lightly sedated and the endoscope is passed down into the stomach. You need a 7-11 foot endoscope to reach the stomach and duodenum in most adult horses and not every veterinary clinic has a portable endoscope of that length. Gastric ulcers can usually be seen just above the margo plicatus. However, some horses are sensitive enough that they develop mild ulcers due to the fasting, which can give a false positive. Once the ulcers are confirmed and graded (mild to severe), treatment can begin.
There is currently only one FDA approved treatment for gastric ulcers in horses – Gastrogard. Gastrogard contains omeprazole which is the same medication in Prilosec for people. Omeprazole inhibits gastric acid secretion, allowing the gastric lining time to heal. Gastrogard comes in a convenient once daily paste and is typically given for 3-4 weeks. A number of other treatment modalities have been described in the literature with varying success rates. Gastrogard has been extensively tested for both safety and efficacy, so it is a proven method to treat EGUS in horses.
But the most important part of treatment is prevention. The various predisposing factors must be identified and addressed. When possible, horses should be allowed free access to hay or grass. Frequent feedings help buffer the stomach acid. If a horse is in a stressful environment, all effort should be made to remedy that situation, either by giving it new pasture-mates, decreasing the workload or moving the horse to a quieter stall. Certain types of grains produce higher levels of volatile fatty acids (VFAs), so switching to a grain lower in fermentable carbohydrates may help.
But there are some risk factors that cannot be changed. You’ll still want to take your horse to shows, right? We have many clients that travel up to Acadia or down to South Carolina, both events that would certainly qualify as predisposing factors for EGUS. What else can you do to prevent gastric ulcers? Fortunately, the active ingredient in Gastrogard (omeprazole) can also be used to prevent ulcers at a lower dose. This medication, appropriately called Ulcergard, is used to prevent gastric ulcers during stressful situations (training, competition, travel, limited grazing, etc). It contains omeprazole at ¼ of the dose in Gastrogard. Is your horse a little ‘off’ the first few days in a new place? Try using Ulcergard before traveling and see if it makes a difference in your horse’s attitude. If it does, it may be a sign that your horse had been developing ulcers with previous travel. The current recommendation is to start administration of Ulcergard several days before an event, give it throughout the event and continue for several days once you have returned home.
Obviously, preventing ulcers is vastly superior to treating them. Have I convinced you yet to start evaluating your horse’s risk factors for EGUS? How about this - a recent study in the Journal of the American Veterinary Medical Association (JAVMA) found that horses can develop ulcers after five days of travel and weekend showing. Five days?! Yes, that is all the time it takes. Scary thought, huh? Raise your hand if you take your horse to the occasional weekend show. Ok, now raise your hand if you are going to consider using Ulcergard next time you show. Good.
We all know gastric ulcers are bad. Now, you know what signs to look for and how to prevent them. Ulcers are sneaky. They can be hard to diagnose and virtually anything can cause them. Please talk with your veterinarian if you think your horse may be at risk for EGUS. Our horses can’t always let us know when they hurt; it’s up to us to keep them protected and healthy.
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