Check out this great article from PetBucket!
Tails serve many practical purposes for our canine companions, from giving them better balance while running to spreading their unique scent to other dogs nearby. Tails are also one of our pets’ key ways of communicating, letting others know when they’re feeling nervous, excited or open to communication. By watching your dog’s wag, then, you can better understand how he’s feeling and what he’s trying to say.
Dogs use their tails, face and body posture to communicate, making his tail one of your pet’s primary means of expressing his moods. In fact, studies have shown that dogs only wag their tails when they’re with company, making it a completely social activity. Watching a dog’s tail, how it’s positioned, whether it’s relaxed and how fast it’s moving can communicate crucial information. A tail held high usually signals enthusiasm, for example, and confident canines tend to hold their tails higher, allowing them to spread more of their scent. A dog holding his tail extremely high or wagging only the tip, however, is likely on high alert and you should avoid him or proceed with caution. Those with their tails low or between their legs are more timid or feeling nervous. Read the rest of the article here.