What does EGUS stand for and why do I need to
know about it?
EGUS is an acronym for Equine Gastric Ulcer Syndrome.
This syndrome is seen in horses of all ages and occurs when
the gastric mucosa (stomach lining) becomes damaged. In the
horse, there are two parts of the stomach, a glandular and non-glandular portion. These two areas are separated by a delineation called the margo plicatus. Ulcers are most commonly seen
in the non-glandular mucosa (lining of the stomach) near the
margo plicatus. The disease is very common, with up to 90%
of horses reported to be affected yearly.
What causes EGUS?
The development of ulcers is multi-factorial. Associated
Feeding schedule: equine gastrointestinal tracts are built to
stressors that can increase the chance of ulcer development
Training and exercise: studies have shown that horses
in training or racing are at higher risk of ulceration due to
increased production of gastric acid in the stomach and de-
creased blood flow to the gastrointestinal tract. Additionally,
the increased pressure and movement in the stomach that
occurs during exercise increases exposure of acids to the more
sensitive non-glandular mucosa.
handle frequent, small meals and continuously secrete gastric
acids (up to 9 gallons per day!). Therefore, if food is absent for
a long period of time, the acid can begin to break down mucosa.
Type of feed: high concentrate feeds or low-protein,
low-calcium hay have been associated with increased ulcer
Environment: travel, competition, limited turnout, and
changes in routine can cause stress and increase risk of ulceration.
Nonsteroidal anti-inflammatory (NSAID) use: chronic
and/or high-dose usage of NSAIDs, specifically phenylbutazone
(Bute) and flunixin meglumine (Banamine), decreases protec-
tive mechanisms of the glandular mucosa.
How can I tell if my horse has EGUS?
Gastric ulcers can be difficult to detect in your horse and
Decreased appetite or a change in eating habits, such as
signs are often subtle. Signs that may indicate that your horse
has ulcers may include:
Mild signs of colic, such as lying down more frequently,
looking at the abdomen, stretching out, pawing, etc. This is
more likely to occur after eating.
disinterest in eating grain.
Decreased body condition and weight loss.
Behavioral changes, such as decreased performance or
reluctance to train.
Resistance to grooming and girth application.
It is important to note that foals may show additional
signs of discomfort if ulcers are present, including lip curling,
bruxism (teeth grinding), or lying directly on their back.
Because NSAID toxicity may also cause colitis (
inflammation of the colon) horses with gastric ulcers from NSAID
use may also have diarrhea and/or edema (fluid accumulation
under the skin, which is typically found on the belly and/or
under the jaw).
The only way to definitively diagnose ulcers is through
gastroscopy, which is a minimally invasive technique. Your veterinarian will sedate your horse and place a small video camera
down into the stomach to look for ulcers. This should be performed after fasting (at least 12 hours) and water deprivation
( 4 hours) to ensure that the stomach lining can be visualized.
Ulcers can be graded from 0-4, with 4 being the most severe.
What is the treatment for EGUS?
The decision to treat EGUS is generally based upon clinical signs and gastroscopic diagnosis of ulceration. The goals in
pursuing treatment of ulcers include pain relief, elimination
of clinical signs, promotion of ulcer healing, and prevention.
While there are many pharmacologic options for treatment of
EGUS, the most commonly used is acid suppressive therapy.
This decreases acid production continuously, allowing the
mucosa to heal.
The only FDA-approved treatment and preventative
medication for EGUS is omeprazole (GastroGard and Ulcer-gard, respectively). While there are less expensive, compounded
formulations of omeprazole available, these are not regulated
and the formulation, drug concentration, and drug quality are
variable and often ineffective. The recommended treatment
dose is 4 mg/kg once daily by mouth for 14-28 days. The horse
should be re-evaluated 14 days after treatment is initiated to
gastroscopically evaluate the response to treatment. Clinical
signs typically resolve or improve within a few days to a week
of treatment, but treatment for up to 8 weeks may be necessary
in severe cases. A dosage of 1-2 mg/kg of omeprazole daily may
be used to prevent ulcer formation, but gastroscopy should be
used to evaluate efficacy.
By Kiersten Wiley, DVM Student (Class of 2014)
Edited by Sandra D. Taylor DVM, PhD, Dipl ACVIM, Purdue Large Animal Internal Medicine