Why Can’t Rats and Horses Vomit?
WouterHorses and rats cannot vomit due to their lack of neural wiring. While rats can regurgitate food to chew their cud, this process is not possible for horses. Rats also lack the neural wiring needed to control the muscles involved in vomiting. Therefore, they cannot open their crural sling at the appropriate time and can’t wrench it open. They are also unable to relax their crural sling while contracting their diaphragm.
In addition to their weak diaphragm, horses have an esophagus that joins the stomach at a slant, making it difficult for them to vomit. Furthermore, their stomach is poorly designed and they cannot have a strong gag reflex, which hinders them from vomiting.
The study also examined the anatomy of the digestive system and brains. Researchers at the University of Pittsburgh examined the brain stems of rats and mice to understand why they are unable to vomit. They also noted that rats did not display vomiting symptoms and did not display abnormal nerve activity in their mouth, throat, and shoulder.
In contrast, horses do not come into contact with toxic substances very often, making it unlikely they would need a vomiting reflex to feed their young. The inability to vomit puts an extra strain on horse owners, who must protect their animals from choking and colic. In addition, they must run away quickly and without triggering the vomiting reflex.
