If anybody has one that I haven't tried I shall be very interested too.
See the two bays in my signature? Lola, the fatty, is very expectant Mum to the yearling in front, said yearling practically docked her Mum's tail overnight then started on Aunties last summer. It still only reaches her hocks.
The ONLY way I found to stop it, and I tried every revolting concoction going, believe me, was to plait the tails up. Too late for poor Lola though, it is a good job she doesn't show any more.
Don't try the chili powder, it doesn't work!! We lost 6 inches of tail trying this one
We lots of different things and nothing really worked, the crib biting stuff was about the best, but bandaging has left us with a problem that the little minx now whips off bandages in a flash! She loved the chili powder, never tried vicks though - wish i'd thought of that one.....
She's two now and mums tail is almost back to normal, so I understand your frustration, like to see the solution for next time.
Sorry I can only comiserate with you, my mares tail is shorter than her foals, my shetlands tail is looking thread bare and my comp geldings tail has never been the same again!