You think your dog loves you. After all, it perks up every time you enter the room, eyes wide and tail wagging vigorously at just the mere sight of its master.Each dog was isolated in a rectangular wooden box and presented with various stimuli. The dogs’ responses were recorded with an overhead video camera.But could it all be an elaborate hoax to squeeze another bowl of tasty bits out of you?The truth may be in the tail. Researchers have determined that the way a dog wags its tail speaks volumes about the way it is really feeling inside.If Fido’s tail is wagging primarily to the right side of the rump, chances are that he is pretty happy to have you around. He may even love you. But if you notice the tail often wagging to the left side, it may be time for canine counseling. Chances are that the pooch can’t stand you.The study into the secrets of the canine mind consisted of an elaborate series of tests that lasted 25 days. The researchers, from the Universities of Bari and of Trieste, both in Italy, measured the tail’s angle when the dog was presented with various stimuli. They also measured the amplitude of the tail wagging and captured the responses on a video camera.Thirty dogs were tested, of which 15 were “intact” males, according to the researchers. Each dog was a family pet and ranged in age from 1 to 6 years. They were placed inside a rectangular wooden box one at a time, with only one small opening out of which to see. Each pet was presented with four stimuli: its owner, an unknown person, a cat (a 4-year-old European male) and a dominant, unfamiliar dog (a Belgian Malinois). Ten presentation sessions of the stimuli were given.Researchers determined that, when a dog wags its tail to the left (left), it is experiencing fear or emotional discomfort. A tail wagging to the right (right) is associated with pleasure or comfort. Angles were evaluated by the line that extended lengthwise through the base and the tip of the tail, with the tip of the sacral spine considered as 180° and the base of the tail as 0°. A Sony video camera positioned directly overhead recorded the responses of the tail. The results were saved on a computer and the angles precisely evaluated.The investigators found that, when presented with their owner, the dogs overwhelmingly wagged on their right side and with considerable vigor. A similar bias for the right side was seen when the test dog was shown the unfamiliar human, although researchers noticed that amplitude dropped off somewhat. When the feline suddenly appeared before the viewing window, the dogs seemed almost indifferent. Tail wagging dropped off noticeably, although there was still a slight bias to the right side. Finally, when the Belgian Malinois (an imposing breed, much like a German shepherd) was presented, the test dogs changed direction and started wagging to the left. The results were reported in the March 20 issue of Current Biology.The researchers said the results fit with what is known about the asymmetries of the brain. The right side of the brain controls the left side of the body and vice versa. The right side of the brain is associated with emotions such as fear and depression. The brain’s left side is associated with love and attachment.A dog’s tail is almost perfectly aligned in the middle of the body; however, because it seems likely that the tail is tied to the brain’s asymmetry, according to the researchers, the tail-wagging results could be used to improve veterinary care.