I have a dartmoor cross new forest, he has always been a cheeky chap but recently his bahaviour has got worse unless the other horses are in I can't catch him from the field and even then when I catch him some times he will spin and try to double barrel me out the field. When I put him in the school he try to bolt on the lunge line and then can't be caught and even if I catch him on the lunge line he bolts again and he is a strong pony. His behaviour has really started to get me down as I don't know what has happened. He is only fed on happy hoof and spearmint. I also found out a couple of days ago that a guy at the back of my yard has fed him a large amount of cut grass could this have something to do with his behaviour?
Can you help? Will be grateful for any suggestions