Horses Can’t Breathe Through Their Mouths

If you’ve ever watched a horse in a full, mighty gallop, you may have noticed something peculiar: Its mouth stays closed. Unlike many other animals, including dogs, which often pant with their tongues hanging out to help them cool down and catch their breath, horses can only breathe through their noses. 

Animals that breathe only through their nostrils, rather than through both the nose and mouth, are known as obligate nasal breathers. A flap of tissue called the soft palate forms a tight seal between the mouth and airway, helping horses breathe efficiently while eating and, importantly, keeping food out of their airways. And since they can’t pant like dogs, horses instead rely on sweat to regulate their body temperatures, sweating up to several gallons an hour during high performance.