Hamster balls may seem like a fun way to let your hamster zip around your home. Unfortunately, they can be very dangerous and stressful, this is due to the little slits in the balls. Some hamsters have managed to get their claws trapped inside and this has led to cases of claws being ripped out.
As hamsters have poor eye sight, they will bump into things such as furniture and the have little control. The slits on the ball also make for poor ventilation, and depending on size can cause back problems.