NotEinstein
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If you have heard that horses cannot vomit, then you would be correct. Like many other species, horses lack the ability to expel semi-digested food and bile from their stomachs. This may sound like a delightful little ability, but, in truth, it is a burden. In humans, the ability to vomit protects us from some forms of poisoning and quickly removes other harmful items we may have swallowed before they can enter our bloodstream. The lack of the ability to vomit can cause severe digestion problems in horses. Colic is one of the most frequently diagnosed medical conditions in horses. Colic is defined as abdominal pain in horses, but this is only a symptom of what can be a much more severe problem. In horses, colic is the leading form of death, and, in any given year, 10 percent of all horses in the world will develop a case of colic.
Both humans and horses have a muscular band around the esophagus near the top of the stomach. This muscle constricts the esophagus, acting like a valve. The valve squeezes the esophagus in a downward manner, so anything going down continues to go down. Anything that wants to come up, however, is stopped by the valve. In humans, our valve doesn’t really work that well. It is theorized that it once worked, but natural selection favored those people who had faulty valves and were able to throw up. So humans with faulty valves became dominant and those with working ones slowly died out. The valve is much stronger in horses, so food and most gases cannot escape upward and through the mouth. In addition, the angle at which the esophagus meets the stomach is much more pronounced in horses, helping to keep the stomach contents from rising. The problem with some forms of colic is that the valve is so strong on horses, the stomach bursts before the valve gives way. This can cause a rapid death in horses. Some horses have been known to throw up, but in most cases they are already very near death when they do so.
 Posted 5394 day ago
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