As anyone who has had a stomach bug - or too much to drink - knows, vomiting can help relieve the symptoms and get rid of any harmful substances in the stomach, and it is something most mammals can do. However, for horses this isn't an option.
Why can't horses vomit?
There are a number of reasons why horses can't vomit.
The first one is their cardiac sphincter, also known as the lower oesophageal sphincter, (the one-way valve between the oesophagus and the stomach) is incredibly strong and only lets content in – not out.
The contractions of muscles in the oesophagus (known as the peristalsis) only pushes food down, not up. This differs to humans, who haveReverse peristalsis and can push food both ways.
And finally, just to make sure food can't come back the way it came in, the oesophagus enters the stomach at a steep angle making it easy for food to travel down but difficult to go up.
The British Horse Society says: "Due to this, horses are at greater risk of colic episodes and swelling of the stomach. If the stomach becomes distended, it's at risk of rupturing so it's important to always call your vet if you're concerned."
This is why, if a horse shows signs of colic, a vet will pass a long plastic tube (stomach tube) through the nose and down the oesophagus – and through to the stomach, so the contents can be drained. Unlike most animals, horses can't do it for themselves.
Saddle up for a journey into the equestrian world
Ever wondered if horse riding is a sport? Or are you curious about the ins and outs of equine ownership? If so, check out our feature about how much it costs to own a horse.
And, if you're looking for present ideas, don't miss our handpicked selection of best gifts for horse lovers.
