I clean out my guinea pigs once a week, and when I start, I put them in a plastic travel cage. This time I put it on the second to bottom stair, as I was doing a more thorough clean out then usual. When I was about halfway between finishing and starting, my piggies decided that they were going to run about in the cage. Suddenly, I heard a crash, and I realised that the cage had rolled, and I literally do mean ROLLED, down the stairs. They seem to be fine, but I really worried about them. Please help!