Modern-day horses suffer from an assortment of gastrointestinal problems. One of the most common is gastric ulcers.
Known as equine gastric ulcer syndrome (EGUS) or equine gastric ulcer disease (EGUD), it is estimated a third of all adult horses, half of all foals, 60 percent of show horses and up to 90 percent of racehorses will develop the condition.
Equine experts believe much of the GI tract dysfunction in today's horses is attributable to a lack of pastures to graze, too much time spent standing in stalls, intermittent intensive training programs, and in some cases, chronic use of certain medications.
Horses Are Built to Graze the Day Away
A gastric ulcer is an injury to the lining of the stomach caused by acid.
In people, ulcers have been linked to Helicobacter pylori bacteria. Most of the acid humans produce is during consumption of food.
The stomachs of horses, however, produce acid even when no food is present, and for the most part nature has designed things such that the stomach can handle all that acid. The top portion of a horse's stomach, called the esophageal region, is the non-glandular portion with a lining similar to the esophagus. This section of the stomach has limited protection against acid.
The bottom or glandular portion of the stomach has a lining similar to that of a human's, and is equipped to withstand a high level of acid.
A horse's natural grazing activity provides protection from ulcers. When she's able to graze all day, the fiber she consumes soaks up much of the digestive acid being produced, which keeps the level in the stomach manageable.
The saliva a horse produces while grazing also neutralizes stomach acid. The roughage consumed during grazing requires a lot of chewing, which generates more saliva.
So the acid that builds up in a horse's stomach is managed by how often she eats. When she's not eating, it can rise to a harmful level. This provides insight into how important grazing seems to be to the health of horses.
An Unnatural Lifestyle Can Lead to Ulcers
A study conducted by Michael Murray, DVM, professor and Adelaide C. Riggs Chair in Equine Medicine at the Marion duPont Scott Equine Medical Center in Leesburg, Virginia, seems to further make the point.
Dr. Murray examined the stomach linings of horses who had spent their lives pastured and allowed to graze freely. Most were normal.
The horses were put in stalls and provided free-choice hay. Anywhere from 24 hours to a week later, some of the horses developed ulcers of varying degrees of severity. The concentrated hay fed to horses is known to increase acid production.
According to Dr. Murray:
"Problems arise when you bring a horse into stall confinement and then superimpose large quantities of concentrate - whether it be grain or pelleted feed. Grain or pelleted feed increases the level of a hormone known as gastrin, which is released by the stomach and acts as a stimulant for acid secretion. Then after eating his grain, the horse might stand for some time without eating hay, and all the while he is producing acid."
Another contributor to gastric ulcers is how intensely a horse is trained. No one yet fully understands the connection, but a demanding training program seems to be a set-up for development of ulcers. It could be that exercise causes the stomach to empty more slowly, leaving large amounts of acid sitting there for prolonged periods of time.
Also, the stress induced by strenuous training can decrease the amount of blood flowing to the stomach, which could make the stomach lining more susceptible to injury from the acidic environment.
And finally, use of NSAID drugs like Banamine (flunixin meglumine) and Bute (phenylbutazone) – especially chronic use – blocks the production of certain chemicals which inhibit acid production. When those chemicals are low in a horse's body, acid levels are generally high, which can contribute to ulcer development.
With all that said, however, Dr. Murray believes it's possible for a horse who has lived in a stall all his life to adjust to the relative unnaturalness of it better than a horse suddenly brought in from pasture and confined. He thinks horses who have lived in stalls all along might be better able to meet their natural requirement to graze by spending more time at the hay feeder.
Dr. Murray also thinks horses with consistent daily routines are less prone to ulcers. By contrast, show and racehorses endure significant fluctuations in their activity levels and feeding behavior, and also have the highest rates of gastric ulcers.
Symptoms of a Gastric Ulcer
In foals, symptoms of a possible gastric ulcer can include:
- Poor appetite; nursing for very short periods
- Intermittent colic; diarrhea
- Excessive salivation
- Teeth grinding
- Lying on the back
Colic is abdominal pain which can cause a horse to turn her head toward the flank, lie down more than normal, and paw.
In adult horses, signs of ulcer to watch for include:
- A change in attitude and/or a drop in performance
- Lack of appetite; colic
- Weight loss of up to 10 percent of body weight
- A decline in body condition
- Lack of energy
Diagnosis and Treatment
A definitive diagnosis of gastric ulcers must be made by a veterinarian using a three-meter endoscope. This is a flexible scope inserted through the esophagus down into the stomach. This procedure will show if ulcers are present in the stomach lining and how severe they are.
It's extremely important to distinguish between gastric ulcers and colonic ulcers, because the treatments are very different. Also, certain FDA-approved treatments for gastric ulcers can make a colonic ulcer worse in some situations.
Gastric ulcers can be life-threatening for a horse, so if you suspect your foal or adult might have the condition, it's important to seek veterinary intervention right away.
Therapy for gastric ulcers in your horse will involve medication and lifestyle changes.
Medications for equine gastric ulcers fall into four categories, including:
- Proton pump inhibitors (example: omeprazole) which inhibit acid production.
- H2 blockers (examples: cimetidine and ranitidine) that inhibit histamine activity. Histamine stimulates the production of stomach acid.
- Buffering agents (examples: Mylanta and Maalox) that neutralize stomach acid that has already been produced. In horses, these agents are short acting (less than an hour) and must be given in large doses.
- Protectants (example: Sucralfate). This group of drugs blocks acid from coming in contact with the lining of the stomach, however, they haven't proved very effective in the more vulnerable upper portion of a horse's stomach.
Dr. Murray prefers omeprazole because it is the only treatment currently FDA-approved and it shuts down acid pumps entirely vs. trying to compete against acid stimulants. It's also much easier to administer than other drugs.
Lifestyle changes would include more roughage in your horse's diet and an increase in the amount of time he spends eating. Putting your animal on pasture is the ideal option.
Alternatively, you can consider installing a specially designed hay bag or paddock feeder that manages the amount of food your horse eats in one session and spreads feedings out over longer periods of time. This more closely mirrors pasture grazing and increases saliva production throughout the day.
Added benefits of these feeder devices are calorie management if your horse is overweight, and less wasted hay.
Other healing lifestyle changes you can implement would include:
- Reducing or eliminating grain from your horse's diet
- Adding probiotics for improved digestion
- Supplementing with appropriate vitamins, minerals and vegetable oils
- Adding as much consistency as possible to your horse's daily life with regard to diet, exercise and housing
In terms of how long it will take for your horse to heal from ulcers, fortunately, many ulcers in foals resolve without treatment. In adults, symptoms typically improve within a day or two after treatment is started, but it takes much longer for the ulcers to fully heal. That's why it's important to continue treatment as your vet recommends so that your animal's ulcers heal completely.
And of course, as is the case with all animals, the more your horse is able to live life as nature intended, the healthier he'll be.