Colic and its Causes

Colic simply means abdominal pain, but the term doesn’t suggest what caused it or the degree of its severity.  Horses are especially susceptible to colic, so it is important to understand the factors that can result in this condition.  The problem can be mild, or it can become life-threatening.  Colic can occur as a result of primary gastrointestinal (GI) tract disease.  It can be secondary to illness in other parts of the body.  It may even be attributable to husbandry and feeding practices.  Colic is the number one health problem seen by veterinarians and the number one reason for death in horses.

One cause of colic may be intestinal parasites.  Large strongyles migrate through and cause damage to the blood vessels that supply the intestines.  Roundworm burdens can be so great as to block the intestinal tract.  Tapeworms may cause ulceration and occasionally intusseption of the small intestine into the cecum, and botfly larvae may cause severe inflammation in the stomach lining and may even block the opening into the intestines.  These parasites are certainly responsible for causing colic pain and must be ruled out first on any symptomatic horse.  Regular deworming protocols and botfly control measures should be established.

Diet and feeding practices are perhaps a very common cause of colic.  Sudden diet change, spoiled feed sources, withholding water, or over-supplementing with processed diets may lead to bacterial overgrowth in the gut or obstruction from bolting.  Horses confined to overgrazed paddocks can develop “sand colic” from ingesting too much soil, which irritates the mucousal layer and may become impacted.  Salmonella is a common cause of colic that may stem from unsanitary conditions around the horse farm.

Colic may also be secondary to other disease processes in the animal.  Respiratory and urinary tract infections are common contributors.  Teeth malocclusion problems that may develop as a result of improper feeding practices and a lack of regular dental exams can cause colic when food is swallowed before it is fully chewed.

Over-confinement may lead to cribbing or wood chewing from boredom, which may also contribute to colicky symptoms.  Even lameness and laminitis can play a role.

While it may have so many contributing factors, colic is pretty easy to recognize.  A colicky horse will become restless and may paw at the ground.  It may roll on its back frequently, and repeatedly look back at the abdomen.  Rolling can become violent, or the horse may lie motionless on its back.  It may have a distended (swollen) abdomen, and may be unable to pass stool.

If colic is suspected, the veterinarian should be summoned to perform an exam sooner rather than later.  Because so many disease processes can lead to abdominal pain, it is important to reveal the underlying cause.  If the horse is approachable, it should be walked at a slow pace until the doctor arrives.  This may help release trapped gas within the GI tract.  Use caution while leading the horse if the it insists on rolling.

The veterinarian will take a history of symptoms and assess contributing factors, perform a complete physical exam, and collect a fecal sample for parasite screening and a blood sample for basic lab work.  A stethoscope will be used to listen for normal abdominal sounds.  An absence of sounds could indicate colic.  The pulse and respiration rates are counted to detect early signs of shock and pain, and a stomach tube may be passed to relieve built up ingesta in the stomach.  Advanced diagnostics may require an ultrasound of the abdomen, or an abdminocentesis (passing a needle into the abdomen to collect any free fluid or gas present).

The treatment will completely depend upon the source of the colic.  This can include anything from a simple change in feeding habits, to floating the teeth to correct malocclusions, to abdominal surgery.  Often, pain medications are administered, and mineral oil as a laxative is delivered to the GI tract via the stomach tube.

Even mild colic needs to be monitored after treatment.  The horse can relapse quickly, developing a life-threatening obstruction in the intestines.  Contact the veterinarian immediately if the horse’s condition worsens.  If colic pain is not controlled by medications and other supportive care, colic surgery may be indicated.