It worked on mine who was also spooky, only prob was as its a powder form he started to leave his dinner if it was in it so had to change after two months. He's on Naf magic now and seems to work too.
I used it on one horse. He used to get more and more wound up if he was somewhere exciting. If I used Steady Up he still got a bit wound up by seemed to plateau. But I only started using it when I was given some by a friend who thought it was useless.