One of the most common reasons dogs wag their tails is to show happiness. When a dog is happy, they will often wag their tail in a wide, sweeping motion.
Dogs may also wag their tails when they are excited. This is especially common when a dog is about to go for a walk, play fetch, or see their owner after a long day.
In some cases, dogs may wag their tails as a sign of submission. This is often seen when a dog meets a new person or animal.
Finally, dogs may also wag their tails when they are afraid. However, the tail wag will be more tentative and the dog may also tuck their tail between their legs.
There are other reasons why dogs might wag their tails. For example, a dog may wag their tail to communicate with other dogs or to get attention from their owner.
A dog who is wagging their tail to the right is usually happy or excited, while a dog who is wagging their tail to the left is often feeling submissive or fearful.
A slow wag is usually a sign of relaxation or contentment, while a fast wag is more likely to indicate happiness or excitement.