Chasing one’s tail is also called whirling- a natural behavior often seen among different species of predators. Tail chasing in older dogs can also be a sign of a behavioral problem. Like humans, dogs can develop compulsive disorders. Sometimes, these disorders cause dogs to chew or lick themselves. In other cases, they can cause them to chase their tails for no apparent reason. Some puppies act as if they are not aware that their tails are attached to their bodies! When they become bored, which happens frequently with young puppies chasing that wagging end back there can seem like quite the cure for boredom.
Often, dogs will chase their tails because they are a bit bored; it is a way for them to have fun and expend some energy. This is especially true for puppies, who may not even realize that their tail is actually a part of their body, but see it as a toy. Generally, as dogs age, this kind of play dies down.
If you notice your dog is going after its tail a lot, and trying to nip or chew on it, you may want to schedule a trip to the vet. Sometimes dogs will chase their tails because they are being bothered by worms or fleas or experiencing some other kind of medical issue.
Some dogs may develop a compulsive disorder that involves chasing their tail. These kinds of behavioral problems can come about for many reasons- confinement, physical abuse, past injury or trauma, separation anxiety, and so on. They definitely need to be addressed!
For reasons that we still don’t really understand, breeds like German shepherds and terriers tend to engage in tail-chasing more than other breeds, even as they grow older. This happens even more when dogs have been trapped indoors for too long.