With branches I only clean them when I do a full cage cleaning, unless there is poo on it. To clean them I spray them with bleach water lightly and wipe them down then let them air dry. If there is poo then I spray it off with the garden hose then I do my bleaching process. If an animal gets sick or parasites (internal or external) I do the bleaching process then bake the stick in the oven at 400*F for about 15 minutes or so. Also if you bring a stick/ branch from the outdoors you should bake it as well.