I have just heard that a horse on our yard has come in this evening with a plait in its mane. So all us horsey lot should be extra vigilant at the moment as this appears to be the way that horse thieves mark their targets. Someone mark the horses, then others come and pick them up.
Having read quite a few of these warnings I am beginning to wonder if it is what we used to call "a horse been ridden by a witch!" The mane gets twisted looking like a plait but quite ragged looking...not tidy. Usually happens in wet or windy weather and it was supposed to have been done by a witch to hold on to the horse while she rode bareback!! I have had a good few of these on my horses over the years, sometimes so tight I've had to cut them out but its really all done by the weather! Hope this is the case ...