KCBS Animal Update: Tail Wagging Might Not Mean Dogs Are Happy

SAN FRANCISCO (KCBS)— We love it when we see a dog wagging its tail and we assume they're happy, but is it really that simple? Dr. Jennifer Scarlett with the San Francisco SPCA says "of course not".

"We love finding more depth and nuance to things we think we know. As people we're very geared towards human communication, but for dogs, body language is very important and we generally think of tail wagging as happiness," she said.

Scarlett continued saying that a recent study shows that all depends on which way the dog is wagging its tail.

Keen observers of dogs have noticed that dogs tend to wag their tails to the right or the left. In the study, they've videoed dogs and showed that video to other dogs. They've found that dogs that wag their tail to the right have a very relaxed demeanor. When they wag to their right, they tend to be happy, according to Scarlett.

When dogs wag to their left, they are more anxious and evoke anxious feelings in dogs that are watching them. In addition their heart rates are increased.

Scarlett said it seems to be the universal tail language amongst dogs of all breeds.

The study's hypothesis held up when it was conducted with pure and mixed-breed dogs.

"I can't tell you how many times I've had people say they were surprised that a dog growled or snarled because their tail was wagging," she said.

The bottom line seems to be you need to take everything into account when interacting with dogs. Look at their body language in an overall context. If they're wagging to the left and seem tense, it might be a cue that we need to back down.

(Copyright 2013 by CBS San Francisco. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)