Originally Posted by Cherie
How long ago was he in a show barn? MANY show horses' tails are 'blocked' to keep them hanging limp. Some are so limp they get tangled up around their hocks and some cannot even lift them well to defecate. Some have worn heavy tail extensions and that limits tail movement. When they 'wake up' or go without the extensions, they can get really swishy tailed.
Spurs usually start the problem in the first place, so riding without them can really help. If the horse was blocked, he may (or may not) gradually get better if he is not aggravated with spurs. If it is a really ingrained habit, it will be difficult to stop in the arena but may go away on the trail, in the pasture or working cattle -- like a new occupation.
To rule out pain, I would give him Bute or Banamine and see if he is the same. I'm afraid it is a result of a lot of show barn training.
He was on Banamine for 8 days for his neck; didn't help the tail swishing. He was never shown until I bought him, but I got him almost 3 years ago from the hunter people.