Is it normal for my dog to chase its tail?
Dogs chase their tails for several reasons. If your vet examined your dog and didn’t find any fleas or problems with your dog’s anal glands, then you could be dealing with a behaviour problem. It may have started when they were bored and became a habit. In some dogs, tail chasing can be an obsessive-compulsive disorder. In others, it’s a source of attention. This type of problem is best dealt with in your home by a person such as myself ( a Behaviourist)
In the meantime, try not to react when it happens. Laughing or scolding him are forms of attention and this could be what they’re after. If there are any incidences that seem to trigger the behaviour, try to get them into a “down-stay” before the tail chasing begins.
Of course, these are only suggestions – some dogs, if they are causing harm to themselves, may need drug therapy in addition to behaviour modification to solve the problem.
Your vet no doubt will refer you to a behaviourist.