Why Do Dogs Have Tails? What You May Not Know About Them

Oct. 21, 2015

Dogs wag their tails for a variety of reasons. But have you ever wondered why do dogs have tails?

Dog owners often find themselves pondering many things their pets do: "There's nothing outside. What are you barking at?" Or "I just took you out 10 minutes ago. Do you really have to go again?" One area you might not give much thought to (outside of the entertainment of watching it wag like a windshield wiper on high during a rainstorm) is a dog's tail. So why do dogs have tails?

What is a Dog Tail?

why do dogs have tails

According to Vetstreet, a dog's tail is just an extension of the spine. It's connected to the dog's frame via the sacrum. Each tailbone section decreases in size the longer the tail is. As in the spine, discs provide a cushion between each tailbone, and muscles help move the tail. Tails originally served as a method of maintaining balance when traversing a narrow path, notes Noah's Friends Veterinarian.

Dogs mainly use their tails to communicate. People mistakenly assume a wagging tail always means a dog is friendly or happy to see them. That's not necessarily the case. A dog's tail wag, in addition to expressing happiness, can also indicate signs of aggression and stress. The key is to watch the direction and manner in which the tail wags, as Psychology Today explains.

dog tails


How to Read the Wag
When a tail points in a high direction and wags vigorously, a dog is happy and excited. If the tail is rigid and pointing vertically, that's a sign the dog feels threatened. A horizontal tail parallel to the ground means the dog is curious or interested in something. When the tail wags in a low position, that means the dog feels insecure. A tucked tail indicates fear, according to the American Society for the Prevention of Cruelty to Animals (ASPCA).

A simpler way to determine the dog's current mood is to watch for the direction of the wag. When the tail wags to the right (the dog's right), it indicates positive emotions. Wagging to the left means a negative mind frame. This is because of the way a dog's brain works.

The left hemisphere harbors positive feelings and controls the right side of the body, according to Live Science. The right hemisphere harbors negative emotions while controlling the left side of the body. Dogs also recognize the right-left wagging indications of other dogs and can tell when another dog is friendly and inviting to approach.

Read more about dog body language at How To Decipher Dog Body Language.

What Are Other Tail Uses?
The tail isn't solely for communication. Last Chance Ranch Sanctuary points out that tails help dogs swim and turn when running. They provide dogs with balance. Dogs also use their tails to spread their scent. Any tail movement distributes his natural scent, emanating from the glands on his tail, says Vetstreet.

why do dogs have tails

What Don't You Know About Tails?
Also, wondering why some dogs chase their tail while others are content with never paying it any mind? According to Vetstreet, tail-chasers may also be suffering from high cholesterol levels. As well, according to the Humane Society of the United States, newborn puppies don't start wagging their tails for at least two to four weeks. And perhaps most remarkably, dogs never wag their tails when they're alone. Tail wagging occurs only in the presence of humans or other dogs, says Psychology Today.

The next time you're out walking or running with your dog and she starts wagging her tail, read the signs she's giving you to figure out what's going on. Once you know, you'll no longer wonder, "Why do dogs have tails?"

Steven Auger is freelance writer whose venture into the world of dog lovers began shortly after meeting his wife, Lauren, and her adorable puggle, Layla. He quickly learned that some of the best friends people will ever have are those that walk on four legs.
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