A. There are several schools of thought for zoomie treatment, ranging from ignore it and hope it stops, to taking your dog off the course every time they zoom, and hope that that triggers them thinking ‘oh. No more fun if I lose focus!’
Think about what may be causing your dog’s zoomies – are they stressed? Have you ‘revved’ them up to go so much before their run that they can no longer focus? Try working a little more calmly and see if that helps.
Do they not understand what you want them to do? If your dog has trouble with higher-level courses, it might have lower-level causes. Go back over more basic things, like obstacle discrimination and focus games to ascertain if your dog had a foundation issue that only showed up in higher-level courses.
I hope this helps! If you can give me more info, I may be able to give you more specific ideas to help your dog conquer the need to zoom! In the meantime, does anyone have any ideas that may help?