Truly an unfortunate circumstance, but like RG I don't understand the need for bring a pet along. The article indicates that the bag did not fit beneath the seat and was a tripping hazard so the flight attendant told her that it needed to go in the overhead. It also sounds like the flight attendant didn't listen or pay attention that the bag contained a live animal and instead treated it like a just a "get your bag stowed so we can take-off" thing. That being said one article claimed that the dog was barking during take-off and then became quiet but the passenger was paying attention to her two young children and never checked on the dog until after they landed....3-1/2 hours later... when she found the dog dead. You'd think that someone would have checked on the poor dog as soon as they could if they cared at all. Sounds like this passenger had more than they could handle between the kids and the dog and the perfect storm ended sadly. Unfortunately, preventable s&^t like this happens.