Concerning horses sense of smell.
Horses have an acute sense of smell. Along with hearing this is one of the main ways that horses take in information about their surroundings. There are a number of different and important ways a horse uses its sense of smell. Since horses are equipped with a strong olfactory lobe, (the lobe that controls hearing in the brain) their sense of smell (though no one is sure) is said to be hundreds of times better than a human’s sense of smell. Because of their strong sense of smell, horses can sense predators from miles away. The sense of smell also plays a big role in the horse’s complicated social structure. When horses greet each other they touch noses to take in each others scent, and horses can also learn to recognize each other by scent alone. In a herd of horses, mares and foals learn to find each other by smell even in a large group. When you are first introduced to a horse, the most polite thing to do is let the horse sniff the back of your hand. This tells the horse that you are not a predator and will make the horse more agreeable to being handled. So the next time you are with a horse, put out your hand and don’t be rude!