A Gish Gallop is a way of logically nesting nonsense so as to defy response and has nothing to do with horses. It's a rhetorical tactic for cranks. Person hearing gal-LUP has only heard it from the polling company, and not the equine context.

The word I think you're looking for is "canter," as in three main gaits of a horse being walk, trot, and canter, with some other ones like gallop, tolt, and more obscure ones. They are defined by the number of beats in the gait. The walk has 4, trot 2, canter 3, and gallop is also 4.

But to extend the dressage metaphors, a Gish Piaffe would be extravagent and showy movement that goes nowhere and stays in one spot, a Gish Passage would be where the extravagent movement is independent of the direction, etc.

Dressage means "to straighten," or "to educate," so one works on the dressage of the horse, and dressage riding is riding with that intent. What people do in the olympics is ride, and it is the overall dressage of the horse that is what is judged. It's one of the few remaining sports in the olympics that is not merely a game. Source: am dressage bro. :)