Why Do Dogs Wag Their Tails?
"It is a misconception that a tail wag is a sign that the dog is happy," says Beth Strickler, DVM of Veterinary Behavior Solutions. "This is one of the reasons that children are often unable to differentiate between a friendly dog and a non-friendly or aggressive dog."
For help with figuring out what the tail wag means, look for the direction of the wag or at how fast his tail is moving. Studies show that dogs wag their tails to the right when they are happy and to the left when they are frightened.
If Baby wags her tail high and back and forth, she's in her "happy place". When she's just being plain nosy, she will keep her tail horizontal to the ground. When Baby's tail is tucked between her hind legs, she's either frightened or being submissive. When she's wagging it low, she's worried or feeling insecure about something.
Dogs wag their tails for other dogs, humans, and other animals like cats. But research shows that dogs don't wag their tails when they are alone because there is no need. Just as humans use smiles and body language as social cues in different situations, our canine friends do the same.
"Dogs are much better at reading each other's body language than we are," says Dr. Bell. "Dogs that are behaving appropriately in social systems use their bodies and tails to communicate with other dogs even as they are observing the tails and body position of other dogs. This helps them avoid unnecessary conflicts."
Dogs also wag their tails to spread their natural scent from their anal glands. Each dog has a scent that's unique to him or her. An "alpha" or dominant dog that carries his tail high will release more of his scent than a dog that carries his tail lower. Often, when we see a dog holding his tail between his legs, he's frightened and doesn't want to release his scent. This is his way of flying under the radar.
Since tails are essential to communication, pooches without tails typically approach other dogs with caution so there's no miscommunication or fights between the two animals. A playful pup might not be able to interpret cues from the tail-less dog, so he doesn't back down, causing the tail-less pooch to resort to biting or other acts of aggression if he feels threatened.