Paul wrote: ↑Mon Nov 13, 2017 6:33 pm
I'm presuming 'Nag-tail' refers specifically to docking and not to banging or shaving the tails?
No, 'nagging' is completely different from 'docking' in late 18th or early 19th century usages. At that time, docking referred to the custom of amputating several of the 15 to 21 vertebrae which comprise the tail 'dock' (the flesh covering the tail from which the tail hairs grow) in order to shorten it
permanently. Needless to say, in those times it was a brutal practice, chopping with a lever-driven guillotine with no anaesthetic, and completed by apply a red-hot iron to the stump of the shortened dock to stem the blood flow. Knowing nothing of bacteria or infections, it was a risky business which caused numerous horse deaths, and increased the expense to the army. (Hence the practice was more commonly applied to cheaper draft animals, pulling goods carts, and banned for cavalry mounts.)
Nagging, by contrast, simply involved 'plaiting' the tail-a simple or more elaborate 'braid', depending on the occasion-with the tail hairs then being knotted in a simple figure-of-eight, or folded and secured to the natural length 'dock' of the tail. When the horse was not in use, it was thus a simple matter to release (un-nag) the tail, so the animal could enjoy its natural defence from annoying insects and 'communicate' with other horses normally.
Banging, singeing, hogging, etc. are terms more normally used to refer to modern horseshow, dressage, and polo practices. Sadly, many imprecise modern writers use the term 'docking' to refer to these activities, and confuse the picture further.
Hope that helps.
P.S. The original Horse Guards order of 1799, referred to by Brendan above, was researched and posted by myself on TMP back in February 2011. I can share with you some of the 'references' if you are interested.