A Horse Owner's Guide to Colic
Amanda M. House, DVM, Diplomate ACVIM (Large Animal)
University of Florida College of Veterinary Medicine
What is Colic?
Colic is the number one cause of death in horses when you exclude old age. The good
news is that the vast majority of cases are mild and resolve with medical treatment. Although
most horse owners hope to never have to think about it, understanding what colic is and
strategies for management and prevention of colic are critical for responsible horse ownership
and management. The USDA's National Animal Health Monitoring System published the
results of a 1998 study on equine colic. They determined that the incidence of colic was 4.2
events for every 100 horses per year. They also determined that 1.2% of colic cases will require
surgery and 11% will be fatal. The cost of colic was estimated to be $115 million in 1998, and
that has certainly increased in the last 10 years. So what is colic?
Colic is a symptom of disease, but is not actually a disease itself. Colic is defined as any
abdominal pain and can come from any abdominal organ, not just the gastrointestinal tract.
Abdominal discomfort from liver or kidney disease will sometimes cause signs of colic. The
signs of colic can vary from mild to severe. Mild, early signs of colic can include a poor
appetite, decreased manure production, lip curling, depression, or laying down more than
normal. The most common signs associated with colic include pawing, stretching out, flank
watching, teeth grinding, bloated abdomen, kicking at the abdomen, rolling, and getting up and
down. It is critical for owners and care takers to know what is normal for their horses, so that
abnormal behaviors can be recognized as soon as possible.
Normal behaviors, appetite, and physical exam parameters can vary a little bit from horse
to horse. In general, adult horses should have a normal rectal temperature of 99-101.5F, a heart
rate of 24-48 beats per minute, and a respiratory rate of 10-24 breaths per minute. The gums
should be pink and moist with a capillary refill time of less than 2 seconds. Most horses will
pass 6-10 piles of well formed manure in 24 hours. Purchasing and using a thermometer and
stethoscope are important steps in understanding the normal physical exam parameters for your
Causes of Colic
Many different problems with the intestinal tract or other organs can cause colic. The
focus of this guide will be on intestinal causes of colic. The average horse has over 100 feet of
intestine from their mouth to their rectum, which certainly leaves a large area for problems to
occur. It is important to remember that a definitive cause of colic is not determined for all cases.
Causes of colic can be divided into three general areas: intestinal dysfunction, intestinal
accidents, and inflammation or ulceration of the intestine. The most common types of colic are
intestinal dysfunctions; which include gas colic, spasmodic colic, and impaction colic. Gas colic
typically occurs due to gas build up in the large colon or cecum. Gas stretches the intestine and
causes pain. Spasmodic colic results from increased contractions, or spasms, in the wall of the
intestine. Fortunately, both gas and spasmodic colic can typically be treated medically and
usually respond to treatment on the farm. Impaction colic is due to a firm mass of feed material
which causes a blockage in the intestine. Horses that don't drink enough water and get
dehydrated, eat poor quality hay, ingest excessive sand, or have problems with their teeth and
can't chew properly are at a higher risk for impaction colic.
Intestinal "accidents" refer to large colon displacements, torsions (twisted intestine), and
strangulations that occur in the abdomen. These causes of colic are referred to as intestinal
accidents because they are considered just that accidents. There is not a specific way to
prevent intestinal accidents from occurring. For example, colon displacements occur when a
portion of the intestine, usually the large colon, moves to an abnormal position in the abdomen.
Although sometimes intravenous fluids, strict fasting, and/or other medical treatments can help
resolve displacements, many require surgical correction. A twist in the intestine or a
strangulation of any portion of the intestine will also require surgery for resolution of the
problem. Since surgical causes of colic can begin with signs similar to milder cases, it is critical
to involve your veterinarian as soon as your horse exhibits any signs of colic.
The last broad category of diseases that cause colic are the inflammatory or ulcerative
diseases. This category includes problems like enteritis (inflammation of the small intestine),
colitis (inflammation of the colon, and usually diarrhea), and gastric ulcers. Inflammation of the
intestine can be very painful for the horse, and cause serious systemic side effects like
dehydration and endotoxemia (a systemic inflammatory response to a portion of gram negative
bacteria). The inflammatory diseases (enteritis and colitis) can sometimes be difficult to
differentiate from surgical problems, although they typically do not require surgery. Rectal
temperatures, mucous membrane color, and white blood cell counts can often help veterinarians
determine if an inflammatory condition is present. Gastric ulcers are often grouped with the
inflammatory causes of colic but typically result in milder signs.
The prevalence of gastric ulceration in Thoroughbreds in race training varies from 70 to
94%, and most sport horses are similarly affected. The horse's stomach contains two different
types of lining the squamous mucosa on the top half and the glandular mucosa on the bottom.
Ulcers can happen in either location, but are much more common in the squamous portion. The
squamous mucosa of the stomach is essentially similar to the lining of the esophagus, and the
glandular mucosa contains the acid-producing cells. Most equine gastric ulcers affect the
squamous mucosa. But, because ulcers can affect various portions of the stomach, causing a
variety of clinical signs, the umbrella term Equine Gastric Ulcer Syndrome (EGUS) has been
proposed to describe the syndrome. Excess acid exposure is the predominant mechanism
responsible for squamous mucosal ulceration, although many details remain unclear.
Clinical signs caused by gastric ulcers in older horses are variable and classically include
anorexia (not eating), weight loss, changes in attitude, and chronic or intermittent colic of
varying severity. Many horses with endoscopic evidence of disease may appear to be clinically
normal or have vague signs that include decreased consumption of concentrates, episodes of
colic after eating, poor performance or failure to train up to expectations, poor quality haircoat,
and decreased condition or failure to thrive. Diarrhea is not typically associated with gastric
Although a diagnosis of ulcers can be suspected based upon clinical signs and response to
treatment, the only current method of confirmation is via gastroscopy. This procedure looks into
the stomach with a small camera and can easily be performed in the standing horse with mild
sedation after a 12-18 hour fast. The principal therapeutic options for ulcer treatment include
histamine antagonists (cimetidine, ranitidine, famotidine), proton pump inhibitors or PPIs
(omeprazole, pantoprazole, rabeprazole, esomeprazole), and the mucosal adherent sucralfate.
Omeprazole is the only agent approved by the FDA for the treatment of equine gastric ulcer
syndrome (GastroGard, Merial, Ltd.). The other mentioned PPIs are marketed for human
patients. After initial treatment (28 days), a lower daily dose has been shown to decrease or
prevent the recurrence of disease in animals maintained in training, and is the basis for
UlcerGard (Merial, Ltd.). It is very important to note that the powder form of omeprazole is
rapidly degraded in an acidic environment, thus the efficacy of compounded omeprazole is
highly variable and these formulations will very often not result in ulcer healing. Omeprazole
has been shown superior to ranitidine for healing of squamous mucosal ulceration in horses in
active race training.
Treatment of Colic
Your veterinarian should be informed as soon as your horse begins exhibiting signs of
colic. Treatment of your horse with pain relieving drugs such as Banamine (flunixin
meglumine) or bute should only be done under your veterinarian's direction. Obtaining a
temperature, heart rate, respiratory rate, and looking at the gums can provide valuable
information to your veterinarian about your horse's systemic status.
Veterinary evaluation typically involves taking a complete history of the episode and
previous health of the horse, performing a physical examination, rectal examination, and passing
a nasogastric tube. Your veterinarian may want to perform blood work, do an abdominocentesis
(belly tap), or perform an ultrasound depending on the equipment they have available. Most
referral centers will repeat much of the original exam done by your veterinarian to determine if
there are any important changes and can also do blood work, radiographs, ultrasound, and
endoscopic examination as deemed appropriate.
Treatment for colic depends on the suspected cause. Pain medication such as
Banamine is typically indicated for initial management. Banamine usually takes about 30
minutes to take effect, so sedatives such as xylazine and detomidine can help relieve pain while
the Banamine begins working. BuscopanTM is another drug that may be administered by your
veterinarian and may help treat spasmodic colic by stopping intestinal spasms. Fluid therapy is
typically also administered by an oral or intravenous route, depending on the severity and
suspected cause of the colic. Laxatives like mineral oil and Epsom salts are often utilized for
impactions. Horses that are exhibiting signs of colic should generally be kept off feed until the
suspected cause has resolved. It is important to remember that mild intestinal upsets and colic
that require surgery may start out with very similar signs. Persistent pain remains the #1
indicator for exploratory surgery in cases of colic. Fortunately, the prognosis for horses that
undergo surgery is better now than it has been in the last 50 years. Most horses will return to
their previous level of competition after about a 3 month post-surgical rest.
What You Can Do
Remember to stay calm if you notice that your horse is showing signs of colic. Remove
the feed, but not the water, from the stall. Walking can help prevent injury if your horse is trying
to go down and roll, but remember to first consider your safety as well as your horse. If the
horse is too painful and cannot be safely walked, leave them in the stall until your veterinarian
arrives. Call your veterinarian as soon as you notice a problem. Take the horse's heart rate,
respiratory rate, and temperature before the vet arrives. Evaluate your horse's gum color and
moisture. It is important to have the horse's previous medical history and diet history available.
Have there been any changes in the horse's routine? This information will be helpful for the
veterinarian evaluating the horse.
Do not give more than one dose of pain medication without consulting your veterinarian.
Do not walk the horse or yourself to exhaustion. Absolutely do not try to pass a tube or force
feed mineral oil. Mineral oil in the lungs can result in a fatal pneumonitis. It is also not
recommended to insert a hose or anything rectally into a horse to give an enema. Newborn foals
in the first couple days of life are an exception to the enema rule, but repeated enemas are not
recommended. Remember that chronic mild signs of colic over several days or longer may also
indicate a serious problem and require veterinary evaluation.
Prevention of Colic
Unfortunately, there are not many absolutes when it comes to the complete prevention of
colic. However, good management and routine health care can certainly help reduce the
incidence of colic in any horse or herd. Establishment of a set routine, regular exercise and/or
turnout, and a high quality forage diet are all important management steps. Any concentrate fed
should ideally be divided into two or three feedings, and grain based feeds should be limited
when possible. Horses should have annual dental care, and older horses may need dental
evaluations every 6 months. Routine fecal examination and deworming for tapeworms are also
critical for good herd health.
How to prevent ulcers is one of the questions veterinarians are asked most commonly.
Unfortunately, short of leaving horses in a field and out of work, there is not a great answer to
this question. Recently, feeding an alfalfa hay/concentrate diet has been shown to reduce the
severity of gastric ulceration in young horses kept in work, relative to a grass hay/concentrate
diet. Other factors associated with a decreased risk of gastric ulceration in Thoroughbreds in
race training include turnout with other horses and training on the property where horses are
References and Further Reading:
1. USDA APHIS. Incidence of Colic in U.S. Horses. October 2001;
2. Bell RJ, Mogg TD, Kingston JK. Equine gastric ulcer syndrome in adult horses: a
review. NZ Vet Journal 2007 Feb; 55(1):p 1-12.
3. McClure SR, Carither DS, Gross SJ, and Murray MJ. Gastric ulcer development in
horses in a simulated show or training environment. JAVMA 2005 Sep 1; 227(5): 775-
4. Merritt AM, Sanchez LC, Burrow JA, Church M, and Ludzia S. Effect of Gastrogard and
three compounded oral omeprazole preparations on 24 h intragastric pH in gastrically
cannulated mature horses. Equine Vet J2003 Nov; 35(7): p 691-695.
5. AAEP and Bayer Animal Health Brochure. Colic: Minimizing its incidence and impact
in your horse. http://www.aaep.org/health_articlesview.php?id=25
6. Horse Owner's Information Home Page at AAEP: www.aaep.org/index.php