Colic is an age-old, life-threatening condition in horses that can be managed successfully if treated quickly. Sometimes, referral to a hospital is the best choice for the horse, even if the condition’s cause or severity is unknown on the farm.  

What Is Colic?

Colic is not an actual disease but rather a set of behaviors caused by pain, said Philip Johnson, BVSc, MS, MRCVS, Dipl. ACVIM-Large Animal Internal Medicine, ECEIM, professor at the University of Missouri, in Columbia, during his presentation at the 2023 EquiSummit, a virtual equine nutrition conference, held Sept. 5-6.

“Mild signs can include loss of interest in food, lethargy, shifting weight around, looking at their flanks, pawing at the ground with the front feet, stretching out, or adopting a straining stance like they’re straining to urinate,” he explained.

When that pain worsens and becomes more extreme, horses might try to lie down when being ridden, get up and down repeatedly, and roll. They often want to keep moving (propulsive walking), or they might fall or collapse.

Contributors, Causes, and Types of Colic

Colic occurs commonly because of the nature of the gastrointestinal tract. “The large intestine is very complicated,” said Johnson.

The large colon has two key “pinch points”: the pelvic flexure and the transverse colon, he said. Each is a 180-degree turn in the large intestine where digesta can easily lodge. Additionally, both locations have a marked narrowing of the lumen (a decrease in the inner diameter) that can contribute to impactions.

Diagnosing and Treating Colic in the Field

After getting the call for a colicky horse, a veterinarian’s goal is to arrive quickly, ensure horse and human safety, provide the horse with pain relief, and perform a comprehensive exam.

Looking at the gastrointestinal tract specifically, veterinarians assess gut sounds, note whether the horse is passing manure, determine if there is fluid accumulation in the stomach (there shouldn’t be), and potentially perform a rectal palpation, abdominal ultrasound, and abdominocentesis.

The rectal exam, said Johnson, is helpful, but a veterinarian can only feel so much of the abdominal cavity. Abdominocentesis involves collecting a sample of peritoneal fluid that bathes the abdominal organs.

“Just by looking at that fluid we can tell a lot. If the normally clear fluid is cloudy or orange/pink, there is cause for concern,” said Johnson. “Worse, if the fluid looks like fecal material, it suggests there was a rupture of the gastrointestinal tract.”

Veterinarians are increasingly using abdominal ultrasound, which can provide valuable information, such as a visual of loops of dilated small intestine that are cause for great concern.

“It’s also important to assess the horse’s cardiovascular system, including the heart rate, packed cell volume as a measure of hydration level, blood lactate levels, the color of the gums and lips, and pulse strength,” Johnson added.

Treatment at the farm includes pain relief and keeping the horse off food during the early hours following a colic episode.

For impactions, which are the most common type of colic, veterinarians administer fluids via nasogastric tube into the stomach. Those fluids, which can include mineral oil or other lubricants, are designed to dismantle the obstruction and stimulate the gastro-colic reflex.

“If the horse has a gas (spasmodic) colic or pelvic flexure impaction, they tend to do very well (with treatment),” relayed Johnson. However, a small portion of horses does not respond as positively to conventional therapies.

Red Flags

“If fluid is accumulating in the stomach and it is not improving over the course of two hours, (I always refer them),” said Johnson. “This indicates there is a severe problem, likely a small intestinal obstruction.”

In addition to fluid accumulation in the stomach, other red flags include severe small intestinal distention palpated on rectal exam, a patient that is refractory to pain medications, and a deterioration in cardiovascular status.

If the horse has a fever, it suggests the presence of colitis, enteritis, or peritonitis. If the horse has head trauma, it speaks to the severity of underlying colic (because they have clearly been rolling and thrashing).

Even if the horse ultimately ends up having a “negative referral,” meaning surgery was not needed, referring provides that patient with access to critical care, surgery if needed, round-the-clock observation, and a laboratory for quick results.

“They’ll need intravenous fluids at the very least, and that is easier to do in a referral setting,” Johnson advised. “Even if it ends up being a false alarm, it’s better to transport the patient to a facility that is equipped to manage severe colic sooner rather than later.”