She was a handfull when I got her she belongs to my son now. She would push anyone around I have her now to the point where she waits on my ques to do what I want her too.
But I found her easier do deal with that the new horse.
You didn't say you've at this awhile and happened to get one that says "no just to say no"
I have one like that. He is 16 and has been with me since he was 2-1/2. He used to be a real snotface but also one of the best trail horses I could ask for. His 16.1H self is capable of being a real bully to a human or another horse.
While he can still be a Pip, I hate that it took my senior horse becoming insulin resistant 4 years ago to find out the Snotface is oat/corn/soy intolerant.
I had taken all my horses off grain and put them on the same base diet as my metabolic horse.
It made such a difference in Rusty's willingness to please that I haven't had to put the riding crop in the bath bucket since. My non-horse husband also noticed the huge difference in Rusty's personality.
I don't feed legume hay to him either - I also know he can't have alfalfa for the same reason. I feed everyone a mixed grass hay that is locally grown.
In Rusty's case, the food intolerance was so minor that I spent all those years blaming his snotty disposition on his bloodline. Never dawned on me he might be oat/corn/soy intolerant but he is.
This is the same horse that I can "forget" to close the gate from his stall going down the aisle and he will get out. He really doesn't want out so he will half halt himself down the aisle way until I say "Rusty stop and step back for a cookie". He will stop and back clear out of the aisleway into the open end stall and I'm not even standing in the barn.
Rusty would've never listened like that back in the day when he was eating oats, corn, and soy
I've had my own horses 52 of my 64 years and I would have never believed that food allergies would make that subtle a difference in a horse's personality and behavior, until I saw it with my own eyes, in my own barn
If you're feeding grain, can you experiment by taking the grain away and just feed him a ration balancer? If he's already on a ration balancer, maybe there's something the ingredients list that he's intolerant to.
Even if the horse has food intolerance, it will still need to un-learn the nasty habits it's developed. Rusty will occasionally try me but he isn't anything like he used to be