Now, my horse Gavyn is a FANTASTIC boy... But sometimes while riding in the arena he will umm "Drop out" and at one point it escalated to him arching his back and snorting/nickering and acting as though he was trying to mount something (Even though there was nothing in there). My trainer was in the barn with me and saw it so she told me to get off and lunge him to see if he would do it when lunging, but no go. So then she told me to bring a mare in from the field, and he had absolutly NO interest in her.
He is the nicest horse to be around, easy to lead (Even around other horses). And it is not everytime that he does this, so I am at a loss as to why he is doing this.
Most of the time he will either drop out or just start nickering when I go to jump off of him.
Once I am off he stops completely, but it is just the fact that I don't know when he is going to do it.
I will tell you that he is in need of a sheath cleaning... Could that be it??