we have 2 cat , one of whom constantly shed 1-inch guard hair . I estimate -lrb- from brushing he -rrb- that the amount he shed per day be about as much as you can hold in you cupped hand . I find that after each run , the Roomba MUST be clean , and this take a really long time since the cat fur get stick and wrap around the brush 's gear shaft to the point where you need scissors to get they off . the fur also get stick on the brush , cause the Roomba to stop pick up any more fur after a short while . all in all , it be faster and MUCH less messy to just vacuum , than it be to clean the Roomba of cat fur after a single run . although the Pet series Roomba may work well for dog , I find it do NOT work well for cat . I regret have get this device .