Shapleys MTG will grow it out longer and thicker, always test a small spot to make sure your horse is not allergic to it first before you go rubbing it all over the tail. It is around $16 a bottle at tractor supply and one bottle lasts forever. The best thing to do is rub it on the tail bone and very very very lightly through the tail, do not soak the tail itself if you do the next step, it will turn to glue if you use to much. Then braid the tail in a loose braid staring about 2 inches below the bottom of the tail bone and roll the braid up small and vet wrap the braid ONLY. Do not vetwrap the tail bone. I usually leave them up until they look like the vet wrap is going to fall off but if you want it to go quicker, take it down once a week and redo everything. It will be slow at first but after a couple months you will see the major difference.
I had goats eat the tail off of one of my mares and it was on the ground dragging behind her and they ate it to the tailbone, they left me fuzz to work with. That was a little over a year ago and now it is almost on the ground again. That was putting MTG on it, leaving it up for 3-4 weeks, and then redoing it. Needless to say, the goats left.
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