Tail communication can be very tricky. Not every wagging tail means happiness and not every tail that is tucked denotes fear.
Rapid tail wagging:
Most likely, your dog is very happy and excited. Any wagging that’s quick, wide or done in a circle means your pooch wants to interact — either for play and affection. Happy dogs tend to wag their tails more to the right. While, when they meet someone new, their tails tend to wag more to the left.
Tucked, Curled or Low-Hanging tails:
These tails indicate submission, fear or pain. If your dog’s tail is tucked around a person or another dog, something is wrong. Never touch a strange dog whose tail is tucked! If it’s your dog, the first thing to do is to make sure your dog is not hurt.
Tails Straight Out:
When a dog’s tail is horizontal from his body, he is in predator mode. When a dog suddenly extends his tail, he’s going to chase something. Dogs engage like this during play — or right before a fight occurs.
Tail Completely Erect:
A tail straight in the air indicates interest. (Hunting dogs raise both their tails and a foot.) However, it could indicate aggression. An erect tail that’s double in size with raised hackles (the hair on the back of the neck and down the spine) is an extremely aggressive stance; he’s trying to scare you off and will attack if provoked.
Slow, Short wags:
Your dog is uncertain. This often happens during a lesson of a new trick or even when you’re speaking to him. He’s interested (and listening), but confused.
Wagging just the Tip:
This is an indication of a dog who is about to defend himself. Be wary if this is a strange dog. If it’s your dog, he is in predator mode; either about to chase or about to fight. If two dogs are engaged like this, a fight is imminent.
Erect tail Wagging Rapidly:
This is the tail communication that is the most confusing because you may think he’s happy (his tail is wagging), but what it really means is that he is about to attack. If you’re a stranger to the dog, he is about to bite you. If it’s your dog, he’s about to chase down some “prey.” If it’s between two dogs, a fight is about to start.