While most cats should be able to safely use these litter boxes, owners must adhere to weight restrictions. Depending on the type of automatic litter, they can usually be used by those weighing three pounds or more. Never risk letting a small cat use an automated box, as this could lead to serious injury.While most cats should be able to safely use these litter boxes, owners must adhere to weight restrictions. Depending on the type of automatic litter, they can usually be used by those weighing three pounds or more. Never risk letting a small cat use an automated box, as this could lead to serious injury.