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
For me, it really helped when I stopped brushing out his tail (of course I would every couple of weeks, though)!
Rub coconut oil in it! Trust me this works amazingly. Not only does it make it grow longer but it makes it very strong and thick! Hope this helps!
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!
Wash and condition it once a week. Let it dry completely then put in detangler and brush gently. Then you can put in MTG, braid it and put it in a tail bag.