I had a 13 year old German Shepherd. I was out playing with her for at least 30 minutes on Wednesday. Thursday morning around 5AM I woke up because she was crying so loud outside. I figured it was just her arthiritis bothering her, or maybe she was having a bad dream, so I grabbed my iPod and went back to sleep. Around 8 that morning, I woke up to go to school. I always say goodbye to her before I leave, so I went to do so. She was laying in front of the sliding glass door, with her eyes shut. I figured, ok, she's old, she had a long night, and she's sleeping it off. I left her alone and went to school. I came back, and she was still there. She was breathing too. I went out there, and she didn't respond. I immediately knew something was wrong. I didn't have the money to take her to the vet right now, so I just sat out there talking to her and petting her, all day and most the night. She died at 10 PM. I don't know what could have gone wrong, and I'd just like to know if anybody thinks it could have been just old age?