Why Do Dogs Have Tails?

You come home from work and, before you’ve even stepped across the threshold, your dog bounds toward you with a tail wagging so energetically that it’s obvious this is the best part of their day.

You’re not wrong to assume that your dog is happy to see you: Dogs wag their tails to convey happiness, just as a tucked tail can indicate fear. As the American Kennel Club explains, communication is a key function of canine tails, and these motions can tell us when our pets are feeling dominant or submissive. Dogs have two anal sacs on either side of their anus, which emit an odor specific to each dog. When your dog wags its tail, it’s also squeezing the muscles around these glands and sending olfactory signals far and wide. If your dog wants to draw less attention to itself, it’ll keep its tail down and steady. (The special scents in the anal sacs also explain why dogs are constantly sniffing each other’s butts.)

But that’s not the only reason tails are a vital appendage for canines. We have our arms to help us balance and move more smoothly—dogs have their tails. “By intentionally swinging the tail to one side or the other in the direction opposite to any tilt in the body, dogs maintain their balance, much the same way a circus tightrope walker uses a balance bar,” Dr. Matthew McCarthy, veterinarian and founder of New York’s Juniper Valley Animal Hospital, told Reader’s Digest.

Breeds that hail from cold climates, like Siberian huskies and Alaskan malamutes, can also curl up and tuck their faces into their bushy tails for warmth.

These factors play into arguments against docking dogs’ tails, and some experts believe shorter tails can negatively impact a canine's ability to communicate. But if your pet already has a docked tail—or a natural bobtail, like many Australian shepherds, for example—don’t worry. There’s a general lack of evidence suggesting that dogs with stumpy tails are “physically or psychologically disadvantaged,” according to the American Veterinary Medical Association.

[h/t American Kennel Club]