A few years ago, researchers discovered a subtle difference in how dogs wag their tails. When a dog sees something positive, such as its owner, it tends to wags its tail more to its right. The wagging tends to go left when it sees something negative, like an unfamiliar dominant dog.
Now, the same Italian researchers report that other dogs pick up on that difference, and it's reflected in their behavior and even their heart rates. Experts say this tail-wagging difference appears to be one way that dogs gauge how other dogs will respond to them.
The study was reported Thursday in the journal Current Biology.