Boomer is only three, but huge (half percheron). I have been doing a lot of natural horsemanship groundwork with him (Clinton Anderson methods specifically), which have helped greatly with getting his respect and teaching him space issues. He has definitely been getting better.
I didn't get out to see him for like 10 days because I had grad school mid-term assignments and marking to do, so I was really bogged down. During this period my coach said he got really naughty. He was apparently very pushy and when the farrier came he was trying to kick and sit on him. While he's always been a tad pushy, the kicking and sitting thing was totally unexpected! He's never done ANYTHING like that before. My coach said it's typical 3-yr-old behaviour, but I was wondering if younger horses are more likely to act like this if you don't work with them more regularly or something? It was just a complete personality switch for him. Generally, while he is a giant lapdog that you have to be firm with in regards to space issues, he's never mean or done anything like kick.