My floor vents are screwed into the floor to prevent the ferrets from lifting them and crawling into the maze of ductwork. The biggest problem is the ferrets trying to use them as a litter box. I guess they like the blow dry! Seriously though, other than that problem they don't bother the vents. I've placed cement blocks (the ones with the openings in them) on top of the vents so they aren't 'litter box friendly' and the air can still blow out of the vent. On my air exchange vent I fashioned a large raised grate out of 1x2" welded wire and placed a litter box on top for them. Even though they have to climb up on the grate they use that particular litter box frequently. Personally if I had a choice I'd have wall vents instead of floor vents with ferrets. hugs. tle www.ferretfamilyservices.org [Posted in FML 5584]