Why does my dog wag his tail?

Our question this week was:

Dr. Debra – I saw a dog that ended up biting someone that was wagging his tail just before he bit someone. I thought wagging tails always meant a dog was happy?

What’s the deal?

Andrew Simons


Hi – thanks for your email. You wrote that you witness a dog that was wagging its tail then bit someone.

You are correct in noting that dogs don’t just wag when they are happy. It is common for some dogs to wag their tail – often in a stiff jerky motion when they are in an aggressive stance.

An article that might be helpful to you is Why do Dogs Wag Their Tails, Aggression in Dogs and How Dogs Communicate.

Best of luck!

Dr. Debra

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