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Educational Series: Colic

By Fairfield Bain DVM MBA Diplomate ACVIM, ACVP, ACVECC

Colic is a term that refers to abdominal pain. Most of the time, it is pain originating from the intestinal tract, but can occasionally come from painful conditions elsewhere (such as chest pain from pleuropneumonia, muscle pain from tying up, or pain from urinary tract obstruction with things like urinary calculi). The art of the physical examination and the ancillary diagnostics your veterinarian might use is to determine the anatomical source of the pain as accurately as possible.

The first step is for you as the owner to recognize colic for what it is. Sometimes, it is as subtle as being off feed indicating some early mild discomfort. On other occasions, it is more dramatic with serious thrashing and rolling – sometimes to the point of self-injury with the horse being dangerous to handle without some sort of sedation and analgesic medication.

Most colic episodes are minor periods of discomfort that resolve quickly, occasionally with administration of an analgesic like flunixin meglumine (trade name Banamine but many generic products of this same drug are available). The first decision is whether the animal really needs any medication, or does it just need close observation? Owners should realize that all medications come with potential adverse effects. Flunixin meglumine, for example, is known for its potential adverse effects like stomach ulcers from prolonged use or excessive dosing, but it also can be such a good analgesic that a serious disorder might go on undiagnosed for a period of time until the analgesic effect has faded.

For more serious colic episodes, examination by a veterinarian is recommended. Veterinarians are trained to evaluate the horse patient in a systematic manner – from front to back – to determine the source of the colic pain. The first step in a colic visit will always be taking the history of the animal. In some circumstances, the severity of pain will require immediate attention, and the history may need to be revisited once treated with sedation and analgesic medication. An owner can expect the veterinarian to observe and evaluate the type and pattern of clinical signs of pain the horse is showing and then perform a systematic examination starting with the usual vital signs – looking at the mouth to evaluate the color of the mucous membranes as well as the capillary refill time which will give them an idea of the animal’s cardiovascular status and tissue perfusion. Then moving to the chest to listen for heart rate and observe the respiratory rate. Then, they will move on to the abdomen to listen for intestinal sounds – knowing that anatomic locations of sounds represent the location of internal abdominal structures. Finally, a rectal examination might be performed to provide additional information about intestinal contents and location. If the animal is showing significant pain or has a significantly elevated heart rate, a nasogastric tube might be passed which is done to detect presence of gastric distension with fluid and reflux from a possible intestinal obstructive process. The goal of the examination is to determine the location and severity of the process causing the colic pain.

Additional ancillary procedures might be performed to add further information in characterizing the problem. The abdominal ultrasound examination is something that has transformed the colic diagnosis over the past few decades. Mobile ultrasound equipment is now quite common in equine practices and can be used to add additional information about intestinal contents and location – aiding in early diagnosis of significant problems like intestinal strangulation, enteritis, or intestinal displacements – just to name a few conditions. Other diagnostics might include lab work like a complete blood count (CBC), serum chemistry panel, and on occasion lactate (to determine severity of vascular and organ perfusion in shock) and tests like serum amyloid A (used to assess the early inflammatory process). An abdominal fluid sample (abdominocentesis, peritoneal tap, also known as “belly tap”) is sometimes collected especially when trying to make a determination as whether there is significant intestinal strangulation present. All these pieces of information are gathered to formulate a more specific diagnosis and a plan for therapy. The goal is to determine the severity and significance of the colic episode and whether the condition can be treated medically or whether it requires surgery. Some conditions do evolve over time and may start out as medical conditions that later become surgical. Occasionally, and thankfully not common, there are situations where the specific diagnosis cannot be determined, and exploratory surgery becomes a diagnostic tool to be considered.

The determination that a colic episode is surgical is generally made based on the severity of signs of pain or recurrence of pain. Other specific indications might include an abnormal finding (small intestinal distension palpated on rectal examination or seen on abdominal ultrasound). The goal is to quickly determine what might be a surgical condition and determine if the animal is a surgical candidate with prompt referral to a surgical facility.

Medical care of the colic patient has improved significantly over the years with ease of administration of large volume intravenous fluids and other medications. Additionally, medical care of the post-operative colic patient has also improved outcomes.

Sadly, there are still some situations where the colic occurred for a period before being recognized, and the condition has deteriorated to the point where euthanasia is the appropriate and most humane decision. All the colic exam procedures mentioned earlier are helpful in making that determination, particularly the ultrasound examination. One specific example of this situation is the geriatric horse that has developed intestinal strangulation by fatty masses called lipomas and has already ruptured the stomach or intestine by the time it is discovered. Prompt recognition of this situation is important. While never an easy decision, when faced with this, the veterinarian can provide the owner with important information in making an end-of-life decision.

Colic is one of the most common reasons for a call to the veterinarian. Knowing what to expect when the owner calls the veterinarian can be helpful in achieving the best outcome.