By Jody Johnson
American Quarter Horse Journal, April 2002 The statistics are startling. As many as 90 percent of racehorses suffer from gastric ulcers, and upwards of 60 percent of performance horses develop the irritable lesions that accumulate along the stomach lining. Unfortunately, most horses don't show clinical signs of ulceration until the condition is severe and painful. But without treatment, gastric ulcers lead to dilapidated body condition, decreased performance and possible death. So, why the high incidence of gastric ulcers in show and racehorses? IT WASN'T THE CHILI CHEESE DOGS Unlike human stomachs, horses' stomachs continually secrete acid, even when they're not eating. Gastric ulcers arise when the acid is not properly neutralized by food in the stomach. Dr. Jorge Nieto, D.V.M., M.V.Z. Diplomate, American College of Veterinary Surgeons, and associate veterinarian of equine surgery at the University of California Veterinary Medical Teaching Hospital explains: "Pastured horses eat all the time. When we take them from the wild and put them in a stall, usually we just feed them two or three times a day. But they are producing acid all the time. In the wild, because they are grazing and eating all the time, the food neutralizes the acid being produced. It's really uncommon for a pastured horse to get gastric ulcers.
"What's happening in the horses we keep stalled is that we are restricting the amount of time that they have food in their stomachs, so the hydrochloric acid in the stomach has time to start eroding the surface of the stomach," he continued. "That's one of the reasons stalled horses have higher incidence of gastric ulcers. So wherever there is a big competition, there are going to be horses with ulcers." In addition to the limited amount of time race and performance horses have food in their stomachs, several other factors can encourage ulcers. Stress from competition, unfamiliar surroundings or an intense exercise program can be culprits. "They might be on a medication that decreases the protection of the stomach," he added. The high-level exercise programs racehorses endure contribute because they decrease the blood flow to the stomach. "If the stomach doesn't have enough blood, it's not as protected from ulcers." WHY THE SENSITIVE STOMACHS? Gastric ulcers occur partly because of the construction of the horse's stomach. "In humans, we have stomachs that have a lot of glands, which produce mucus and bicarbonate, and that's going to neutralize the acid," Nieto explained. "The horse's stomach is different. The lower, glandular part of the stomach has a lining that produces mucus and bicarbonates that neutralize the acids. But the top half, the squamous portion, which is similar to our esophagus, contains no mucus or bicarbonates and doesn't have the capabilities to be protected from acid. In the junction between the glandular portion of the stomach and the squamous half that cannot be protected, ulcers can develop if acid is allowed to accumulate." While gastric ulcers are common occurrences, the good news is that many horses are not bothered by them. "A lot of horses have ulcers, and you have no clue they have them," said Dr. Scott McClure, D.V.M., Ph.D., Diplomate, American College of Veterinary Surgeons, and assistant professor of equine surgery at Iowa State University's College of Veterinary Medicine. "A little ulcer here or there is probably no big deal and probably doesn't bother them too much. When the horse becomes debilitated and the disease gets ahead of them, where you start seeing clinical signs, that's the point at which you need to start worrying about ulcers and treating them." SO WHAT ARE ULCERS? "When acid starts chewing the squamous mucosa, it creates holes, which are ulcers," Nieto said. The ulcers take many shapes and forms and can vary widely in severity. "Ulcers can be bleeding, or they can have a lot of tissue growing around them," he said. "They can be as small as little dots or as big as quarters. They can be clusters or just one ulcer. They can get so big that they actually perforate the stomach. Those horses die."
Amazingly, ulcers can develop in just a matter of days, McClure said. But, they also can heal quickly. With proper treatment, the stomach can regenerate healthy lining within a month. TUMMY TURMOIL Because most race and show horses spend large amounts of time in stalls on a regimented feeding schedule and a stressful exercise schedule, they're more likely to develop gastric ulcers than their pastured counterparts. So it's important to watch stalled horses for signs, though clinical indications rarely occur until the horse is in substantial pain from considerable stomach damage. Key clues include poor appetite, decreased performance, poor-quality hair coat and abdominal pain similar to colic. "In most horses, the signs are subtle and not easy to see," Nieto said. "Maybe they just aren't eating well. Maybe they aren't performing as expected." Be aware of conditions that could affect your horse's stress level and encourage the onset of gastric ulcers. "Feeding is a contributor, but stress is clearly a major factor, whether it's environmental stress, disease stress or other kinds of stress," McClure said. "If you put a bunch of stallions together with some mares, and they're standing in stalls all day looking at each other, they'll likely have ulcers just from standing there worrying about each other." He cites an example of a backyard Quarter Horse that was hauled to a county fair for a weekend of showing. The brief change of environment caused enough stress that the horse immediately developed a terrible case of gastric ulcers. After the horse was returned home to his pasture, the ulcers - and the horse's discomfort - cleared up within 72 hours. ULCER ALERT There is only one way to determine if ulcers are the cause of a horse's discomfort or decreased performance - esophagogastroscopy, commonly known as stomach scoping. McClure describes the process: "The stomach has to be empty, so we usually muzzle the horse the night before and scope it the next morning, about an hour after pulling away its water," he said. "Most of the time, we can see 90 percent of the stomach, which is all you need for an adequate visualization." The procedure involves a 3-meter endoscope fitted with a light and a camera that is maneuvered down the throat and into the stomach, similar to stomach tubing for a colic. "We use a set of stocks to restrain the horse, a very light sedation and sometimes a twitch," he continued. The image is displayed on a screen as the scope is guided through the stomach to look for potholes in the mucosa. "The junction of the glandular (at the bottom) and the squamous (at the top) portions is where most of the problems are found," he said. "It's probably because the acid from the bottom part is splashing up a lot more onto the squamous portion. But we definitely look at the entire stomach." If scoping determines the presence of debilitating ulcers, McClure prescribes a treatment regimen. "Then we rescope in two to three weeks to make sure there's notable improvement," he said. "That's normally when I'll cut treatment doses down. I try to make sure I've got significant improvement at a treatment level, then I'll back it off to a preventative level." HOW HORSES SPELL RELIEF Many equine medications on the market, including antacids, acid pump inhibitors and histamine blockers, serve as temporary treatments and preventatives for gastric ulcers. To cure the ulcers, McClure admits, there's only one medicinal option - omeprazole, marketed as GastroGard®, the only FDA-approved equine gastric ulcer medication. This oral paste, administered like a dewormer, blocks the stomach's acid pump and is effective even while the horse maintains an active exercise schedule. While it's an expensive form of medicinal treatment, it's the most effective and least laborious - administered just once a day. While medications are helpful for healing a performance horse, the absolute best, sure-fire treatment of ulcers is simple … but not as practical for a competitive schedule. "The easiest way to treat gastric ulcers is to take the horse from its stressful condition where it's working, and move it to the pasture where it can eat all the time," Nieto said. Free access to grass or hay will quickly heal ulcers and provide relief by slowing the speed of feeding, providing constant food to neutralize acid and stimulate saliva, which acts as a protective buffering agent. "Most of the time, the ulcers are going to dissolve," Nieto continued. "But it's hard to put racehorses or other high-level performance horses out to pasture because you don't want them to be eating all the time, and you need to keep them under controlled conditions. So, in these cases, medications need to be introduced. If you change the environment a little bit and give them medication, the ulcers will disappear and you can maintain the clean stomachs for a long time with maintenance while continuing to race successfully." McClure says keeping free-choice hay available to performance horses as much as possible will greatly improve and prevent ulcers. "Horses are continuous acid secreters," he reminded. "The more roughage you can keep in the stomach to buffer it, the better." PLAY DEFENSE If you're a competitive horse owner, it's not just your horse's lack of constant, free-choice food that should have you worried. The stresses of competition, traveling, strange surroundings and demanding exercise schedules can exacerbate the formation of ulcers. So Nieto offers some suggestions to keep your horse healthy and comfortable. First, watch for clinical signs of gastric ulcers, including any changes in behavior, performance or eating habits. If you suspect your horse is uncomfortable, seek a veterinarian with stomach scoping resources to determine if gastric ulcers are present. If ulcers are the culprit, talk with your veterinarian about appropriate pasture turn out and medications. It's important to follow up with additional scopes to see whether the ulcers have improved, then adjust the medications accordingly. To stave off ulcer development if your horse's activities make him a likely candidate, use a preventative medication regimen prescribed by your veterinarian. Also, keep free-choice hay available - the constant feeding will keep acid from accumulating in the stomach. On a good note, Nieto says gastric ulcer cases, while still numerous, are less severe today than they were 10 years ago. He attributes this to increased awareness of the disease, its treatments and preventions. STARTLING STATS Nieto took part in a recent study, where a group of ulcer-free, 2-year-old racehorses were followed during their training at the track. The scientists found that by week eight of their training, most of the horses had developed ulcers. By week 18 of training, all of the horses had ulcers. "The racetrack environment is stressful, and stress is a factor in gastric ulcer development," he said. "Mostly it's the restricted access to food - not in volume but in time - that cause the ulcers." Nieto and his colleagues continue to study the most effective treatments and preventions of gastric ulcers. JUST LIKE THE PURPLE PILL
Horses' most-effective treatment option. McClure and Nieto stand behind omeprazole (Gastrogard®), the same ingredient that makes up Prilosec®, which treats acid reflux disease in humans. Manufactured by Merial, the acid pump inhibitor has been the most successful treatment and maintenance option in multiple equine studies. Plus, it allows performance horses to remain on their exercise schedules during treatment. "Omeprazole is about your only option for curing gastric ulcers," McClure said. Though antacids and histamine blockers are less expensive, McClure warns that they're not always a good choice. "The antacids (Neigh-Lox) are all fed with meals," he said. "If you think about it, the horse doesn't need antacid when there's food in his stomach. It's a contradictory deal. It doesn't make a lot of sense." Medications that block histamine receptors (Cimetidine, Ranitidine) provide a good partial block, they said, but their effects are short term, and the doses must be given three to four times a day. |
