Z has been a kind and gentle 14 year old quarter horse for the 3 years I have owned him. He is suddenly having temper tantrums: while under saddle, if I ask him to turn down a path or at a corner and he wants to go straight, he will shake/snake his head and kick.  He almost threw my husband a few weeks ago, and did manage to throw me the next day.  While walking him a few days ago, there was a new to the neighborhood horse calling out with a persistent whinny.  Z was hell-bent to get to that horse.  He fought while on a lead rope, kicked and eventually did give in to go the direction we wanted, but this is dangerous.  Any ideas on how to break this new display?  All ideas appreciated.

"Sudden" changes in horse behavior are usually brought on by an accompanying sudden change in the horse's environment or health. A decrease in exercise (laziness) for extended periods between riding sessions or lack of a warm-up session before riding ( fresh horse) may also explain the behavior you describe. A cold stiff saddle that doesn't conform to a few extra pounds gained on winter rations would also be suspect. If he's getting good and regular exercise, responding to handling and cues from the ground during warm-up and round pen sessions and his tack fits properly but he still acts out under saddle, I'd start considering pain as a potential issue. Maybe arthritis aggrevated by colder temperatures. Or something new coming on.

 I'd suggest running him through a basic training evaluation as if you were thinking of buying him. That may provide some insight toward a training or laziness issue. If he does fine there, it might be time for a vet check. Good luck. ~FH

Is he only doing this under saddle? If he is, check your saddle thouraly before trying lots of possible expensive things.  It is very possible that something is poking through of something, especially if you have had the saddle for quite a while.   It does sound dangerous.  Has there recently been a new horse kept with him? My gelding started acting up on me when he started getting beat up in the pasture.  Whatever the cause I do agree that something has to be done.

If he is just suddenly doing this, my first notion would be to first have him thoroughly vetted; blood work and everything...he could have ulcers, or something else that is making any handling painful, or otherwise 'irratible' to him; although unacceptable, you need to know the cause and treat as necessary.

 As soon as you have gotten any physical causes out of the way; treated if necessary, then if the behavior still is problematic, I would be finding a trainer to help you simply work through his tantrums.