The pre-poo dance is one where he dashes back and forth like a ping pong ball between two irratic players until he's worked himself into a poo-frenzy. At that point, he's built up enough internal inertia to expel his waste products with gusto.
Once he has freed himself of the weight and discomfort of poo, Zeus must run about in circles in exaultation. Apparently the great relief and sense of accomplishment is more than his poodle-self can contain and he must run in random directions at full speed and intensity to dispel the excess energy.
Frankly, I could do with less dynamic pooing... just go out, walk around for a bit, squat, then step away to allow "Dad" to clean up. That's what I want.... not some modern dance version of "freak out"!