Okay. I've tried it, and the Wahl Pet Pro, which looks exactly like the device in the video I posted, works great for ripping a straight seam. Most of the time since my last post was spent finding the thing and then threading the machine and sewing a seam to test it on. It's almost as fast to unstitch as it was to stitch. I'm thrilled, because the dog was not at all fond of this thing, and I thought I'd wasted money on it. Thanks, Diannia, for mentioning it.