Ulcers are a common medical condition in horses and foals.
“It is estimated that almost 60 percent of foals and one-third of adult horses confined in stalls may have mild ulcers,” according to Dr. Race Foster, world respected veterinarian from Rhinelander, Wis.
Up to 60 percent of show horses and 90 percent of racehorses may develop moderate to severe ulcers. “However, about 50 percent of horses with ulcers show no outward signs of the gastrointestinal disease,” Foster pointed out.
Because ulcers are so common, and can occur as a result of a number of factors, the condition is often called “equine gastric ulcer syndrome” or “equine gastric ulcer disease.”
“To understand why horses are prone to ulcers,” Foster said, “It is helpful to know some horse anatomy.”
A horse’s stomach is small compared to humans. It is divided into two distinct parts. The non-glandular portion is lined by tissue similar to the lining of the esophagus. The glandular portion is lined with tissues which produce acid and an enzyme needed for digestion of food.
“In humans, eating stimulates the production of hydrochloric acid,” Foster explained. “In the horse, however, hydrochloric acid is constantly being produced. So, if a horse does not eat, the acid accumulates in the stomach and can start to irritate the stomach, especially the non-glandular portion.”
There are multiple factors that can increase the risk of ulcers in horses including not eating, the type of feed, the amount of exercise and medications.
Horses in natural or pasture environment graze and thus eat many small meals frequently. “This way, the stomach is rarely empty, and the stomach acid has less of a damaging effect,” Foster noted. “If horses and foals do not eat frequently, the acid builds up and ulcers are more likely to develop.”
Type and amount of roughage can play a major role in ulcer development. “Hay requires more chewing and stimulates production of saliva which is swallowed and helps neutralize stomach acid.
“There is an increase in acid production when concentrates are fed,” Foster related. “Alfalfa is higher in calcium and helps decrease the risk of ulcers.”
As the amount of exercise increases, there is often a change in feeding which increases the risk of ulcers.
“Exercise may increase the time it takes for the stomach to empty, so large amounts of acid can remain in an empty stomach for a prolonged period of time,” Foster sated.
“Stress itself may decrease the amount of blood flow to the stomach, which makes the lining of the stomach more vulnerable to injury from stomach acid.”
Chronic use of non-steroidal anti-inflammatory drugs such as phenylbutazone (Bute) and Banamine blocks the production of particular chemicals which decrease acid production, contributing to the development of ulcers.
In foals, signs of gastric ulcers include: intermittent colic after nursing or eating, poor appetite and nursing for only very short periods, teeth grinding, excessive salivation, diarrhea and lying on the back.
Signs of ulcers in mature horses include: poor appetite, weight loss and poor body condition, bad hair coat, mild colic, mental dullness or attitude changes, poor performance and lying down more than normal.
“Gastric ulcers can be life-threatening, so if horses show any of these signs, a veterinarian should be contacted,” Foster insisted.
The only way to definitively diagnose ulcers is through gastroscopy, which involves placing an endoscope into the stomach and looking at its surface. To allow this, the stomach must be empty, so most horses are off feed for 18 hours and not allowed to drink water for two to three hours prior to the procedure.
With light sedation and possibly a twitch, the endoscope is passed through the nostril and down the esophagus into the stomach. The light and camera on the end of the endoscope allows the veterinarian to observe the lining of the stomach.
Medications and changes in management practices are necessary to treat horse ulcers.
“Different medications are used to decrease acid production, buffer the acid that is produced and protect the stomach lining from effects of the acid,” Foster detailed.
“Because acid is constantly being produced in the horse, antacids are effective for only a short time and require large amounts,” Foster warned. “This makes them relatively impractical, though their use on the day of a show may be beneficial.”
In addition to medications, changes in management are almost always necessary. “Roughage should be increased, and the amount of grain decreased,” Foster commented. “However, putting the horse on pasture would be the best alternative.”
Additionally, the veterinarian shared that supplements can be fed to increase vitamins and minerals. Vegetable oils will add the calories the horse may need.
“Many ulcers in foals heal without treatment,” Foster advised. “In adults, the clinical signs may improve within a couple of days after starting treatment, but it takes far longer for the ulcer to actually heal.
“If you stop the treatment earlier than your veterinarian suggests, the ulcer may not completely heal,” Foster emphasized.