I think that there is no point in playing the blame game.
Yes the child should have been better supervise.
Yes the dogs should have been taken care of better. They shouldn't have been chained up and they should have been in a secure yard.
But the facts remain the same, the child wasn't supervised, the dogs weren't in a secure yard.
Instead of throwing blame around we should all step back and look at how we live our lives in regards to the training and supervisation our kids and pets have.