I honestly never heard of it until recently & that is only because of a teenage girl on my FB. OMG I love reading her updates ,seeing her pics & videos with her & her horse.That horse & her a attached at the hip
The relationship they have is something else.....
The horse counts ,bows, lays on command,follows & shadows her moves,rides now with no tack,she calls & he comes running from across pasture etc. It is nothing for them to just lie out & enjoy the sun together they certainly have a love affair