You love your dog. But how well do you really know your dog? He or she’s been keeping some important facts from you—ones you may find surprising, funny, and maybe disturbing. So read on, and never look at your pooch in the same way again.

Dogs Have 18 Muscles to Move Their Ears

These muscles allow dogs to move their ears in intricate ways, which are very important to picking up sounds.

A Dog’s Nose Is Its Fingerprint

Dog noses have unique patterns that can serve to identify them, similar to human fingerprints. Also, the wetness of a dog’s nose is a sign of good health and helps them in gathering scents.

Dogs May Be Able to Fall in Love With You

Scientists have discovered that love is chemically apparent when a dog and its owner look into each other’s eyes. Specifically, a study found an uptick in the level of oxytocin (sometimes known as “the love hormone”) in a dog and its owner when they stare at each other.

Dogs Sweat Only on Their Paws

Dogs have sweat glands only on their paws, not the rest of their bodies. Since they do not use sweat to cool off, dogs have developed another way: They ventilate and exchange heat through panting.

Small Dogs Can Hear Sounds in Higher Ranges

Dogs’ ears are perfect tools to detect sounds. Dogs can hear sounds that are two-times beyond our range—and it appears small dogs are actually better at it.

Dogs Mark Their Territory with Glands in Their Paws

Dogs are not, in fact, trying to clumsily bury their poop. They are just performing yet another territory-marking ritual. With the glands on their paws they spread their scent and let other dogs know they are around.

Male Dogs Lifts Its Leg When it Pees as a Sign of Dominance

Dogs’ urine contains markers that inform other dogs of its presence, social standing, and sexual availability. Dogs lift their legs as high as they can so they can “distribute their message” better and allow its scent to travel further.

Dogs Are More Aggressive When Being Walked by a Man

The presence of a leash, the sex of the owner, and the sex of the dog all play a part in the aggressiveness of a dog. Dogs walked by a man have been found to be four times more likely to attack and bite another dog.

Scientists think that dogs dream similarly to us and replay moments that they have previously experienced. You can tell that a dog is dreaming if they are twitching their legs or bark in their sleep. Small dogs have more dreams than big dogs.