Well, Dexter is almost 10 months old and recently returned from in-kennel training. We're doing a lot of walking around town and he's walking great on a loose leash. I use a martingale collar. He always avoided those large see-through metal grates on the sidewalk. I tried to get him to walk over them but he'd balk and I thought they do look a little scary, so I didn't push it. Now, however, he refuses to walk over those solid metal plates on sidewalks. Not the large ones on the street but the ones that are maybe 10-inches wide and stretch from one side of the sidewalk to the other. I don't want to pull him through and I'll try high-value treats the next time we go. Any ideas? Thanks much.