Generally, the symptoms of a horse in distress from acute colic is pretty straight forward. The real question is what type of colic your horse may be experiencing and, accordingly, how does this point to the appropriate treatment? To cut to the chase, the race horseman has to primarily worry about three types of colic: (1) stomach distention, (2) small or large intestinal impaction/distention, and (3) spasmodic colic. There are a number of symptoms the horseman can look at for answers. The first is to evaluate the history of the colicky horse. Then evaluate the affected horse's posture/attitude , listen to the gut sounds, and pass a stomach tube--if practical. Later, to get an idea of the seriousness of the colic, note heart rate/pulse, examine color of mucus membranes, and monitor blood pressure. Some of these procedures may sound beyond the capabilities of most lay-people. Not so! They are quite simple and can tell you much about your horse's condition. The key is to know what is normal for your horse. One can not wait till colic strikes and then not know what your horse's normal signs were. The horseman should have a stethoscope and an appropriate blood pressure cuff waiting and ready for use in the tack room or trunk. He should have periodically used these instruments on his horse and know what is normal. Only then can the symptoms and seriousness of colic be interpreted.
Most likely the first scenario: you will go into the barn and find your horse pawing and acting very uncomfortable. If it is feed time, he will show no interest in eating. He may go down, lay a few seconds, look rearwards, perhaps roll once, then pop back onto his feet. Depending on the pain being experienced, there will be a wide array of gradients of these signs, all the way from mild anxiety to profuse sweating, violent rolling, and rapid respirations.
The first thing is to quickly evaluate your horse's history. What happened that day which might precipitate colic? Was he inadvertently fed a different ration? Was he worked differently? Is his water buckets still full? The predisposing conditions found in most racehorse shedrows are dehydration, diet changes, injury, and stress. Dehydration is mainly seen in the Fall when freezing weather brings new drinking habits to the horse. Water buckets may be frozen. Whatever the cause of dehydration, be it temperatures, stress, work, etc. the horse's lack of water can stimulate ingesta impaction. A diet change can take in the feeding of new or different hay/grains. Injury to the horse can precipitate colic by a pain reflex that acts by decreasing the activity of the intestinal musculature. Make no mistake, the nervous system and the gut are closely related. Pain can also cause a decrease in water consumption. Stress can go hand in hand with pain or can be a result of tougher training works or other barn routines which may put stress on the horse. The gastrointestinal tract tends to shut down from many variances of stress, opening the horse up to bouts of colic.
Posture and attitude of the colicky horse can give further clues. The amount of pain being experienced will be reflected in the posture and attitude. As a very broad rule of thumb, generally, low grade pain means that the point of colic is further away from the stomach, most likely in the large intestines. The more severe and consistent the pain, the more likely the anterior portions of the GI tract are involved, but be aware that horses are individuals and pain is a very subjective gauge at best. The degree of anxiety can pretty much be a gauge to the pain being experienced. Depression in the colicky horse is always a bad sign and a result of exhaustion and impending shock. The posture of the colicky horse can be difficult to interpret at times. This does not mean that one should disregard stance, just be wary of a definite meaning for any one individual affected horse.