Try using MTG+ I use it for all the horses I ride even if they have long and thick tailes it helps with scratching and stuff to make it grow and stay healthy and they won't ruin it by scratching it your horse will love the feeling of having a nice non itchy short tail
Yes! There is a supplement called BioMane and I use it! It is a 30 days supply or more and in 30 days their mane and tail will grow! It is like my 10th day using it and my horses tail is longer! It is a little expensive but it works!