How can I understand my dog's emotions? Dogs express emotions by wagging their tail. So If you know the signal from your dog's tail wagging, you can more understand its emotions. 1. raising the tail high and wagging slowly It means that your dog feels anxiety and uncertainty. Or It means a challenge or warning or signal of feeling superior to the other. 2. wagging tail from center to left. Wagging the tail toward left side(or only one side) is...