The term colic simply means pain in the abdomen. There are many causes for such pain, ranging from the mild to the life-threatening or fatal. The figures suggest nearly one in ten horses will experience colic at some point in their lives. About 30% of colic cases are caused by impaction in the Large Intestine due to overfeeding of grains and/or dry roughage. About 10% of colic cases are potentially fatal.
Understanding the underlying causes of colic in horses and the ways the condition may vary can make all the difference. Unfortunately, in some cases of horse colic, the underlying cause will be unknown.
Some cases of horse colic can be traced to gas accumulating in the horse's digestive system. In horses, gas colic can be traced to various parasitic infections, chronic stress, intestinal inflammation, ulcers in the stomach or colon, or intestinal food fermentation. Gas colic is less serious than other types of colic if it is treated quickly enough. However, owners who suspect that their horses have gas colic still shouldn't wait to get their horse's proper veterinary care.
Impaction colic is also widespread among horses. Essentially, in the case of impaction colic, the horse's colon will be blocked by matter that the horse cannot digest. Horses that get enough water and eat high-quality feed should be less likely to get bouts of impaction colic, although other factors will certainly come into play. One specific case of horse colic that relates to impaction is sand colic, which is indeed caused by horses amassing dirt and sand in their digestive systems. Sand colic cases are more prevalent in certain climates than others, due to varying levels of sand in horses' grazing areas. In the drier months, there is often a spike in sand colic cases from horses being supplementary feed on open ground.
A horse can suffer colic as a result of a ruptured stomach, due to undigested materials or accumulated gas. Some of the rarer types of horse colic can also be the most potentially serious for the horses. Colic that relates to a torsion of the digestive system can mean that the horses will effectively starve, at least until the condition can be treated. In similar cases, a horse's intestinal tract can become obstructed due to a receding intestinal structure. These sorts of dangerous types of colic can be caused by untreated parasitic infections, although even something as benign as gas can be a factor. With dangerous torsions and intestinal obstructions, veterinarians may have to resort to surgery.
Surgery comes with its own risks and can never be taken lightly, since the anesthesia, the surgery itself, and the subsequent physical therapy can all come with their own risks. While otherwise healthy horses may stand a reasonably good chance of surviving their surgeries, veterinarians will still only recommend surgery in a minority of horse colic cases.