Tuesday dog blogging

Fascinating.

In humans, the muscles on the right side of the face tend to reflect happiness (left brain) whereas muscles on the left side of the face reflect unhappiness (right brain).

Dog tails are interesting, Dr. Davidson said, because they are in the midline of the dog’s body, neither left nor right. So do they show emotional asymmetry, or not?

To find out, Dr. Vallortigara and his colleagues recruited 30 family pets of mixed breed that were enrolled in an agility training program. The dogs were placed in a cage equipped with cameras that precisely tracked the angles of their tail wags. Then they were shown four stimuli through a slat in the front of the cage: their owner; an unfamiliar human; a cat; and an unfamiliar, dominant dog.

In each instance the test dog saw a person or animal for one minute, rested for 90 seconds and saw another view. Testing lasted 25 days with 10 sessions per day.

When the dogs saw their owners, their tails all wagged vigorously with a bias to the right side of their bodies, Dr. Vallortigara said. Their tails wagged moderately, again more to the right, when faced with an unfamiliar human. Looking at the cat, a four-year-old male whose owners volunteered him for the experiment, the dogs’ tails again wagged more to the right but in a lower amplitude.

When the dogs looked at an aggressive, unfamiliar dog — a large Belgian shepherd Malinois — their tails all wagged with a bias to the left side of their bodies.

Thus when dogs were attracted to something, including a benign, approachable cat, their tails wagged right, and when they were fearful, their tails went left, Dr. Vallortigara said. It suggests that the muscles in the right side of the tail reflect positive emotions while the muscles in the left side express negative ones.