Horses do not breathe like other mammals—they only breathe through their noses because they cannot breathe through their mouths. The equine respiratory system functions by inhaling and exhaling through the nostrils. This is thought to perhaps be an evolutionary feature to prevent debris, such as dust and dirt, from entering the horses’ lungs as they run. Their large size makes it so that horses are only able to inhale as their front legs stride, but not as their legs land because their internal organs are proportionately larger than other mammals’. Horses’ lungs would then not be able to expand efficiently to allow oxygen in during landing due to the force that would shift their internal organs.
More about horses:
- A horse’s teeth appear to continuously grow through its lifetime. The animal is born with its teeth fully formed beneath the gums and they gradually become more visible over time.
- An average horse’s lung capacity is nearly twice as great as an elite human athlete’s.
- Horses are physically unable to vomit because the band of muscles that surround their esophagus are so powerful. In fact, if a horse does vomit, it’s generally a sign of a possibly fatal stomach rupture.