I have a palomino and 2 Appaloosas with white tails. And I use plain ol bleach. I just pour it on the tail in place of shampoo... let it sit for about a minute. Then I rinse the tail really good. And put conditioner in it. Its fast simple and A LOT cheaper than whitning shampoos. And I have never had luck with whitingin shampoos.
Many people have sighed for the 'good old days' and regretted the 'passing of the horse,' but today, when only those who like horses own them, it is a far better time for horses. ~C.W. Anderson