The morning after the veterinarian injected the little white mare with a sedative, and then a lethal dose of barbiturates, the herd did not want to go out to the pasture. They stayed near the gate where the sweet elderly Arabian had taken her last breath.  “The timing is good,” the veterinarian had said. “Not too soon, and not too late.” She had taken care of Echo for many years. None of us wanted the thin mare to endure another hard winter, even with the herd beside her, even with abundant hay....