Equine
gastric ulcer syndrome is a common condition, both in performance
horses, such as racehorses, and in foals.
More
than 90 percent of performance horses have gastric ulcers, and
between 25 and 50 percent of foals do.
“Ulcers
are sores in the lining of the stomach,” explains Dr. Wilkins, who
is boarded both in equine internal medicine and in equine emergency
and critical care.
In
horses, the top portion of the stomach is lined with flat
non-glandular cells and the lower portion has glandular cells.
According
to Dr. Wilkins, approximately 80 percent of equine gastric ulcers
occur in the non-glandular upper portion, which is less resistant to
injury from stomach acid. The glandular tissue is more resistant to
damage because it secretes mucus.
“Ulcers
in the upper portion of the stomach are caused by stomach acid,
whereas glandular ulcers occur when the mucosal protection and blood
flow are impaired, which may be related to the use of non-steroidal
anti-inflammatory drugs,” says Dr. Wilkins.
There
are multiple risk factors for equine gastric ulcer syndrome. During
intensive exercise, such as training or racing, the body concentrates
the flow of blood to the horse’s heart and muscles, and a reduced
amount of blood flows to the gastric mucosa of the stomach, which can
result in ulcers.
Intense
exercise also increases the intra-abdominal pressure, causing
compression of the stomach, which in turn may force acid that is
normally in the lower portion of the stomach into the upper,
non-glandular portion. Ulcers may arise, since the upper region has
no mucosal secretions to protect it from acid.
Horses
fed a diet high in carbohydrates are also at increased risk for
ulcers.
“Excessive
amounts of carbohydrates and sugars will ferment in the stomach,”
says Dr. Wilkins. “The byproducts of this fermentation are thought
to synergize with the stomach acid and may lead to non-glandular
ulcers.”
Clinical
signs of gastric ulcers in adult horses include poor appetite and
body condition, attitude changes, mild to moderate colic, decrease in
performance, and a dry, poor hair coat.
Horses kept on pasture are less likely to develop gastric ulcers.
Pamela Wilkins, DVM, PhD, DACVIM, DACVECC
In
foals, clinical signs include poor appetite or intermittent nursing,
colic, poor body condition, frequently lying on their back (indicates
gastrointestinal pain and not necessarily an ulcer), grinding of
teeth, excessive salivation, and diarrhea.
However,
these signs are only suggestive of an ulcer. For a definitive
diagnosis, a veterinarian must examine the horse via endoscopy, a
nonsurgical procedure in which a light and camera attached to the end
of a flexible tube are inserted down the throat and into the stomach.
Images from inside the stomach are displayed on a monitor, enabling
the veterinarian to determine definitively whether there are ulcers.
Equine
gastric ulcer syndrome may be treated using management modifications
or medical therapy or a combination of these approaches.
“Management
modifications may include reducing the level of exercise, limiting
periods of fasting, and changing the diet, such as by increasing the
amount of roughage and reducing grain concentrate in the diet,”
says Dr. Wilkins. “Horses kept on pasture are less likely to
develop gastric ulcers.”
In
horses as in people, stress can play a role in ulcer development. Dr.
Wilkins recommends that owners limit stressful events for horses,
such as trailering, overcrowding, and long-term confinement to a
stall.
Medical
treatment of gastric ulcers includes either antacid therapy (to
neutralize the acid) or anti-secretory agents.
Anti-secretory
medications and more specifically use what are called “proton pump
inhibitors.” These medications work at the level of the parietal
cell, where the acid is being produced, to inhibit acid formation.
“The
most effective treatment of for equine gastric ulcers combines
management and medical interventions,” advises Dr. Wilkins.
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