If your dog eats one or two they can die, same with small children and the elderly. Their hairs cause intense itching at best. And if the hairs are inhaled they can do serious lung damage. It isn't anything to mess about with. When we used to have them on the playground at school we'd be banned from going outside. If we had them near the house the dogs weren't allowed out. It is a serious not joking matter. We've had friends end up in hospital and animals die because of them.