Fifteen or 20 years ago, few of us worried about horses getting ulcers, unless they were on bute. Veterinary texts published in the ’70s don’t even mention them, except as an infrequent finding in very ill foals. Today, we’re told 60 to 90% of all horses have stomach ulcers. We decided to find out what those numbers mean in terms of a horse’s health and performance.
First, it’s important to realize that ulcers occur so often and heal so rapidly without treatment that pathologists consider most of them to be of little significance.
A 1990 study (Murray et al) of 32 Thoroughbred foals (aged two to 60 days, on five farms) reported ulcers in the nonglandular portion of the stomach in about half of the foals scoped. Less extensive but still visible lesions were observed in 16 of the 19 foals that were less than 30 days old. Foals were re-examined in 35 and 135 days, at which time there was spontaneous healing in the nonglandular ulcers. Glandular region ulcers were more rare, but 80 percent of these healed on their own.
The situation in adult horses is a little more complicated, but the basic point is that the discovery of an ulcer is not in and of itself a reason to push the panic button.
Adult-horse ulcers are also more commonly found either in the nonglandular stomach or at its junction with the glandular stomach. High acid activity in the fluid produced by the glandular stomach definitely plays a major role in the formation of the ulcers, but other factors — including bile washing back into the stomach from the small intestine and fatty acids produced by fermentation in the nonglandular stomach — also play a part. The only adult horses studied by endoscope and found to be free of ulcers were those turned out on pasture 24 hours a day.
Pastured horses obviously have a more natural diet, and diet does contribute to ulcers. Simply changing from pasture to hay and confining a horse to a stall may cause ulcers (Murray et al 1989).
A study in ponies (Coenen 1990) reported no ulcers in hay-fed ponies but ulcers present in 10 out of 27 ponies on hay and grain. Tinker in 1997 reported high grain feeding increased the risk of colic (of all causes), but this effect was greatly reduced if whole grains were fed.
The grain connection is far from 100% clear, however. Sandin et al (1998) reported the size of the meal, not whether it was grain or hay, was more important in release of gastrin, the hormone that triggers acid production. They also reported that a grain meal results in a slower but more prolonged release of gastrin than hay does.
Although Coenen’s study showed more of the meal was left in the stomach 3.5 hours after feeding grain than with hay, by 12 hours after feeding the reverse was true. Interestingly, the stomach acidity was higher at this point if hay only had been fed than if it was hay and grain.
The most reliable way to produce ulcers in a horse is to fast him. Multiple studies have proven that periods as short as 12 hours without feed can result in low-grade stomach irritation, which becomes worse if it happens repeatedly. In fact, periods of fasting are used to induce ulcers in horses for experimental purposes.
The reason fasting is troublesome is that the horse has evolved to secrete stomach acid nearly continuously (about 45 minutes out of each hour) and around the clock, rather than only in response to a meal. This works well, as horses with access to food will eat nearly continuously if that food is grass or hay. Eating also triggers the release of saliva, which is high in the buffering agent bicarbonate, and the food itself will soak up some acid. If the stomach sits empty for a prolonged period, the acid is not buffered by food and saliva, and the stomach will empty less frequently, allowing the irritating fluid to remain on the lining.
Exercise routines, too, may make a difference. A 1994 study by Furr and Kronfeld showed that simply starting an exercise program results in more stomach acid secretion. Horses allowed adequate adjustment time to their diet were then started on an exercise program and showed greater levels of gastrin release in response to eating than they did when they were not being exercised.
As if diet and exercise routines weren’t enough, there are more, less obvious, contributing factors to ulcers. Virtually anything that causes irritation to the stomach and a break in the lining may become an ulcer as the stomach “juices” go to work digesting their own damaged tissues. Any alteration in intestinal function further down the line may also be associated with stomach ulcers. Insufficient blood flow or loss of blood flow can cause the lining cells to die, resulting in an ulcer.
Stress is also a suspected cause, however, several studies have been unable to document a rise in cortisol, the stress hormone, during these periods. One (Vatistas 1999) even showed a drop.
Given that 80 to 90% of high-performance horses scoped have gastric ulcers, it’s easy for unrelated symptoms to make it onto the symptom list. You could assemble high-performance horses with hair loss or watery eyes and still find a high number of ulcers, but that doesn’t mean there is a connection between the two. The truth is, even experienced researchers can’t diagnose a stomach ulcer by symptoms alone.
The most commonly listed symptoms of gastric ulcer include:
With the exception of mild colic, none of these are specific and are just as likely to be found in a horse with pain from a brewing lameness. A bout of mild colic doesn’t cinch the diagnosis either. This could occur from any digestive upset, even an electrolyte imbalance. More suggestive are loss of appetite for grain, signs of mild pain after eating, teeth grinding and belching.
In 1992, Dr. M. Murray, a prominent researcher on gastric ulcers, did a study of 111 colic cases presented to a university hospital. Of these horses, 91 had ulcers. However, an ulcer was confirmed as the primary cause of the colic in only 31, based on the facts that no other abnormality was found, the horses responded clinically to therapy with H2 blockers and the appearance of the ulcer improved. The ulcer was suspected as a cause, or at least a contributing factor, in 26 others.
This means that even with endoscopic confirmation of an ulcer, you can’t blame the ulcer as the cause of his problems, unless other problems have been ruled out and, most importantly, the symptoms improve with specific ulcer treatment.
Gastrogard: Prescription Therapy
In March 1999, Merial announced that the FDA had granted approval for the first anti-ulcer prescription medication for horses, Gastrogard (omeprazole), which is the equivalent of the human drug Prilosec. The once-daily dosing and paste formulation make it ideal for horses. Extensive controlled studies have proven its efficacy and safety. The major drawback is cost: about $40 per day full dose, $1,200/month for the first month then $600 for a recommended additional month of half dosing preventative therapy.
However, before the approval of Gastrogard, veterinarians were using other prescription human medications to treat ulcers. Carafate (sucralfate) is a stomach protectant, but results with this were poor. Both Zantac (ranitidine) and Tagamet (cimetidine) have also been used, although dosage recommendations for these are scanty.
A 1989 paper by Furr and Murray reported Zantac to be effective, especially for lesions in the nonglandular stomach, the most common site of spontaneous equine ulcers. Another paper by Murray reported Zantac to be effective at 6.6 mg/kg three times a day, with 80 to 90% healed in three weeks, and a 1989 study by Murray showed it to be effective in preventing ulcers as well. A German paper reported success with Tagamet at 5 mg/kg four times a day. At these dosages, using a Zantac generic (ranitidine) would cost $13.15 per day (prices for 250 count/300 mg tabs obtained online from www.rxusa.com).
Although one of Merial’s Gastrogard news releases claims “Apparent Widespread Treatment Failure of H2 Blockers” (Tagamet and Zantac are H2 blockers), the literature seems to indicate otherwise, as does the experience of many veterinarians. The problem with using H2 blockers is the same as for any unapproved drug. There are few details available on dosages, side effects, other drug interactions. Vets make recommendations based on their experience and that of their peers. If something goes wrong, the vet could be liable. Most vets are therefore now less likely to recommend an unapproved drug over Gastrogard, unless you press them for details on other options.
There’s no question that Gastrogard works, but it’s also undeniably expensive. Since there are a variety of nonprescription ulcer treatments/supplements available, we decided to try these on horses showing clinical symptoms of gastric ulcer. Candidates were showing nonspecific ulcer symptoms, as well as at least one symptom more classical for a stomach disorder (refusal of grain, pain around meals, tooth grinding or belching). Most were high-performance horses in active training. Some had histories of digestive problems that traced back to bute.
We had the quickest and most reliable results with U-Gard. This product contains aluminum- and calcium-based antacids and a mix of direct acid neutralization and soothing/coating ingredients. U-Gard was used on eight horses in race training and/or actively racing and one mare with poor appetite dating back to a period of heavy phenylbutazone use.
All responded to having U-Gard sprinkled on their feed by a return to full appetite within 24 to 36 hours. Reports of the horses licking their tubs clean were common. Attitudes improved tremendously, as did weight gain. Horses were kept on U-Gard three to four weeks, with no relapses noted in a three-week follow-up period.
The only thing we didn’t like about U-Gard was the aluminum. Ironically, it also probably helped make it work so well. The aluminum compound does mop up acid molecules, but it is also recognized as a mild irritant by the stomach, which is how it stimulates the healing.
Long-term use in people is associated with mineral deposits in the stomach and loss of calcium from bone. It can also adversely affect the immune and nervous systems. Aluminum toxicity is evidently widespread in horses, as indicated by hair mineral analyses.
While we can’t deny this product rapidly controlled symptoms of gastric ulcer — and the aluminum compound used is among the most inert and least likely to be absorbed — we can’t recommend it for indiscriminate long-term use or as a preventative measure.
Nutrient Buffer is a blend of calcium and magnesium antacids in a coating oil base that the manufacturer believes also gives it a time-release effect. When done with their acid-neutralizing function, these ions also boost the body’s general supply of buffers, which the manufacturer believes are in short supply because of the load of organic acids horses’ (and human) bodies carry as a result of toxin/pollutant exposure. The product also adds zinc, as this important trace mineral is also commonly in short supply.
We had some palatability problems initially, but after dosing the horses with it for a few days they began to feel better and readily accepted it in their feed. Clearly improved grain appetite and attitude were seen at four to five days with weight gain following. Four out of five horses showed resolution of symptoms. The fifth horse was somewhat atypical in that bloating and diarrhea were prominent and probably not an ulcer case to begin with.
G.U.T. — short for Gastric Ulcer Transnutrients — has a unique blend of ingredients. In addition to the antacids, it contains the protectants kaolin and cellulose. It has gelatin as both a protectant and a source of rapidly available amino acids for healing including glycine, which is also an antacid. Chlorophyll has a long history in alternative medicine as a gastrointestinal treatment because of its anti-inflammatory, antioxidant and healing effects. The gamma oryzanol from rice-bran extracts has been shown experimentally to have a protective effect on ulcer formation, particularly ulcers believed to be induced by stress or fasting (Itaya et al 1976).
We supplemented four horses with ulcer-like symptoms with G.U.T. Two responded rapidly with improvement within three days, one had a partial response (ate better and somewhat brighter but still not on full feed at three weeks and energy level low) and one no response. Both horses also had some obvious bloating and periods of soft manure.
Tract Guard was designed more as a preventative against intestinal problems than an ulcer treatment per se. It has antacids, protectants and digestive enhancers. The electrolyte component helps keep adequate water in the intestinal tract to encourage normal digestion. Response to Tract Guard in two horses was good but slow, taking about two to three weeks for the effects of increased appetite, decreased bloating and weight gain to start to appear. One of these horses had a history of scanty manure production alternating with soft manure that resolved completely on the Tract Guard — an effect closer to what it was designed to do.
Immune One is designed to replace part of the diet with a palatable pellet high in antioxidant activity and containing the immune stimulant larch arabinogalactan, which encourages the development of a normal population of intestinal bacteria. As with Tract Guard, we didn’t see much in terms of rapid relief of ulcer-like symptoms, but its long-term use was associated with weight gain and resolution of intermittent bloating and diarrhea in two horses.
Gastric ulcers can occur easily in horses with the combined effects of heavy exercise, stall confinement, large meals and long periods without eating. However, not all ulcers absolutely require medication.
Gastrogard is the only treatment approved by the FDA with data on effectiveness and safety to back it up. However, other human medications have been used in the field with success. This choice is up to your veterinarian. Horses with severe ulcerations and symptoms to match should be treated at least for the initial 28 days with an effective prescription drug.
For less severe symptoms, and/or after the initial drug therapy, you may have other choices. We had success with a number of nonprescription/nondrug supplements. The highest response rate and most rapid response were obtained with U-Gard at a reasonable cost. However, we can’t recommend long-term use because of the aluminum and suggest Nutrient Buffer or G.U.T for those uses, with G.U.T. costing less.
Also With This Article
“Ulcer Location, Type And Intensity”
“Non-Prescription Products And Manufacturers”
“Medicines At Work”
“Ulcer Support Products”
“The NSAID Effect”
“Management For Effective Ulcer Prevention”
“Nationwide Gastric Ulcer Screening Results”