I adopted my horse from a rescue - he was returned by his previous adopter for being unrideable due to headshaking syndrome. I didn't find him unrideable, but he clearly has seasonal discomfort that makes him twitchy and he has difficulty maintaining a consistent contact when he's uncomfortable. I find that having him on Shake No More Gold from March through October in New England keeps him comfortable so he can always give me his best effort. I notice a definite difference when I try to take him off it earlier in the year so I'm confident that it's helping him. His version of headshaking syndrome is not severe, and every horse's needs are different, but if you're trying to support a horse with seasonal discomfort I would definitely suggest giving this a try.