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Despite voluminous research on its causes, colic remains a health threat to even the best managed horses. The gastrointestinal tract of the horse is long, windy, and precision built to turn forages and feed into the energy required for all manner of sport and leisure. Set against this efficiency, however, is the foil of fragility. A kink in an intestinal coil, a collection of gas with no means of escape, an obstruction at any point along the pipeline—all can injure the tract, sometimes irreparably.

How far has the science of colic come? Nat White, a veterinarian and past president of the American Association of Equine Practitioners, reminisces about what colic looked like decades ago in this Q&A.

For background, why did you choose to study colic? What attracted you to this specific field of study? How did you wind up being an authority on this health problem? 

During August of 1972, 15 horses with colic were admitted to the University of California, Davis, Teaching Hospital for surgery. Fourteen died or were euthanized. The fifteenth, which survived surgery for an enterolith, returned two months later with fatal liver disease. I thought there had to be a better way to save horses with severe intestinal disease. My experience as a surgeon initiated my entry into research aimed at understanding the diseases causing colic. Much of the knowledge I attained was from seeing as many cases as possible and garnering information from each case. I am convinced my efforts and that of many others in both research and education have improved the outcome for horses over the last four decades.

When did you first begin to study or research colic in particular? At that time, what were the primary research interests in the field? What was happening?

My first venture into research on colic was taking electrocardiograms on horses suffering from colic at Davis. The changes seen in horses in shock indicated a direct effect on the heart. Subsequently, during two years at Kansas State University while studying pathology, examination of intestine combined with training in electron microscopy set up the opportunity to investigate the ultrastructural changes during intestinal ischemia (lack of blood flow).

This became a primary focus for research due to the poor outcome for horses suffering from intestinal strangulation. The serious effort to investigate the effect of intestinal ischemia started with Dr. Jim Moore, then at the University of Missouri. We worked on a project that demonstrated the effect of reperfusion injury, which helped to explain the continued intestinal degeneration after what we hoped was a successful surgery. The results stimulated both of us to seek resources to complete more research. This also resulted in creation of a colic research team at the University of Georgia. During the subsequent decades the research focus expanded to include epidemiology, endotoxic shock, diagnostic tests, surgical technique, critical care, and evaluation of treatments.

In the early years of your training, what was considered state-of-the-art technology when it came to diagnosing colic? Was diagnosis based solely on clinical signs? What were those signs? 

While at Davis, my role as an intern was to work up colic cases and attempt to make a diagnosis. Clinical signs consisting of heart rate, auscultation, evaluation of stomach reflux, and rectal examination were the primary diagnostic tools, as they are today. Lab work was restricted to packed cell volume, total protein, and complete blood count. Blood gas, electrolytes, and liver enzymes were not initially evaluated but could be helpful after treatment was initiated. We often had to wait until the next day to get these types of laboratory tests completed.

Evaluation of peritoneal fluid was just starting. At first, we often waited for the fluid to become serosanguineous before diagnosing a strangulating lesion and recommending surgery. Now the need for surgery is more often based on pain and physical signs when peritoneal fluid may be normal. We also started using serum lactate to provide a prognosis, but it was not easily obtained for timely evaluation. Lactate is still a key component of the evaluation including measuring lactate in peritoneal fluid. The addition of abdominal ultrasound has been a major improvement in the ability to make an early diagnosis.

In those days, what were the standard treatments for different types of colic

Treatments in the 1970s consisted of mineral oil, pain relief (with phenylbutazone, choral hydrate, and dipyrone), and surgery. Surgery became more successful after the introduction of halothane anesthesia, which helped the recovery compared to the results with intravenous anesthesia. Administration of large volumes of a balanced electrolyte solution had just started to be used in the early 1970s and was responsible for improved outcome.

The introduction of flunixin meglumine in the late 1970s replaced other treatments and became the primary drug for treating colic and endotoxic shock. Because it is a potent analgesic, we had to learn how not to overuse it. Flunixin meglumine is still a primary treatment for colic, and evaluating the horse’s response to its initial administration is now an important way to determine the severity of intestinal disease. Treatments are now much more focused-based on making a diagnosis. However, for simple colic, analgesia and hydration are still the primary treatments.

Finals words, Dr. White?

There is an old saying: “As long as there are horses, there will be colic.” Colic remains a mystery and a challenge. However, it is important not to accept that diseases causing colic are unsolvable. Solving the mystery requires research and research requires financial support. Currently there are not enough research dollars to sustain the in-depth research programs needed to investigate the diseases affecting the horse’s gastrointestinal tract. Educating the horse owner about the need for financial support is critical for a future with less equine colic.

What else does Dr. White have to say about colic? Check out the Kentucky Equine Research Conference 2018 Proceedings.

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