Why Do Dogs Have Tails?

Of all the things we love about dogs (and there are a lot), their sweet little faces and wagging tails take the cake. You probably know that your dog is telling you something with its tail, whether it’s the “OMG you’re home!” of an excited wag or the “back off, human” of a tail held high and stiff. Aside from mood indicators, have you ever wondered, “Why do dogs have tails?” And, for that matter, why do dogs chase their tails or do other weird dog behaviors, like wag their tail to a certain side?

As it turns out, dogs with curly tails, long and bushy tails, and even naturally bobbed tails have those appendages for many reasons. We asked pet experts to satisfy our curiosity. Here’s what they had to say about why dogs have tails.

What are dogs’ tails made of?

“A dog’s tail is basically an interlocking, flexible core of bone that is an extension of their back[bone], wrapped in muscle and covered in skin. Within, there is a rich supply of blood vessels and nerves,” explains veterinarian Matthew McCarthy, DVM, founder of Juniper Valley Animal Hospital in Middle Village, New York. A dog uses the muscles in its tail to make it wag, curl, lift, lower, and turn.

But those are just the basics.

There is a seemingly endless number of ways these components mesh together to form a variety of sizes and shapes, whether the tail is attached to a purebred or cute mixed-breed. “Dogs have the greatest morphological diversity of all mammals,” says Dr. McCarthy. “For example, all horses are basically alike, except for size. Same for pigs, humans, etc. But an Irish wolfhound and a mini Pugapoo are still kin.”

Why do dogs have tails?

Dogs have tails for three essential reasons: They aid a dog’s balance and movement. They help some dogs stay warm. And they’re one way a dog can communicate with others, including you.

Tails aid balance

Tails provide an important counterbalance for dogs when they need to navigate narrow spaces and jump. When they leap to clear something, they throw their tail upward, which helps with the trajectory of the jump and, hopefully, helps them land on their front feet.

And like a rudder, a tail will help a dog turn quickly when running or swimming. “By intentionally swinging the tail to one side or the other in the direction opposite to any tilt in the body, dogs maintains their balance, much the same way a circus tightrope walker uses a balance bar,” Dr. McCarthy says.

Tails provide warmth

When it’s too cold for dogs to go outside, some northern breeds, like the Shiba Inu and Siberian husky, use their heavily furred tails to cover their noses and face to stay warm.

Tails help with communication

We know dogs have the mechanics to move their tails. But can they control them? “A dog’s tail is more like our eyebrows—responsible for putting our expressions out to the world but somewhat beyond our conscious control,” says Dr. McCarthy.

Dogs can consciously control the muscles that cause the tail to move, but generally, it’s basically on autopilot, driven by doggy instinct, says Jamie Freyer, DVM a veterinarian with Veterinarians.org.

Dogs begin to transmit messages via their tails when they’re very young. “Puppies begin to use their tails to send signals to their mom and littermates after just a few weeks of age, and later on, [they signal] their pack mates,” says Dr. McCarthy.

When it comes to communicating with other dogs, tails send clear messages of dominance and submission. Tails carried high release more of the dog’s natural scent from the anal glands and are typically a sign of dominance. Submissive dogs trying to keep a low profile carry their tails lower to mask the odor.

Do all dogs have tails?

If you’re a connoisseur of dogs, you may have noticed that some have longer tails, while others have something of a stump. There are a couple of reasons for this. Some puppies have their tails surgically amputated in a process called tail docking—more on that later. Other dogs are born that way. Nearly nonexistent (or bobbed) tails can occur naturally, thanks to a mutation.

You would think short-legged dogs, such as Pembroke Welsh corgis or fox-like schipperkes, would need tails as much as other breeds. Yet they (and others) seem to get by without them. In fact, the bobtailed Jack Russell terrier is actually one of the fastest dogs in the world. And naturally bobtailed (or surgically docked) dogs perform exceedingly well in agility competitions, hunting, retrieving, and herding.

What gives? It remains a mystery. “There are no published scientific studies comparing the locomotion of tail-docked dogs with those that are undocked,” Dr. McCarthy says. “It is possible that dogs are just so good at these activities that slight performance deficits due to short tails are not easily detected.”