Then， without any warning， Sam began suffering from convulsions and was diagnosed as having a weak heart. I had no other choice but to have him put down. The pain of making that decision， however， was nothing compared with what I experienced when I had to leave Sam at the vet and walk into our house alone. This time， there was no Sam for Lightning to greet and no way to explain why she would never see her friend again.
In the days that followed， Lightning seemed heart-broken. She could not tell me in words that she was suffering， but I could see the pain and disappointment in her eyes whenever anyone opened the front door， or the hope whenever she heard a dog bark.