My Mother's family were Dust Bowl Sooners who made their own Grapes of Wrath, ended up in Wyoming and my Father's family were sharecroppers who also went west, ended up in Arizona, before eventually coming back to Alabama where our pre-Sooner ancestors had started from.
I suppose because of that sort of upbringing I learned a different take on the situation.
My grandpa did it back in the 1930s. Would take him less then a day. People would bring their dogs to him for him to break them of bad habits or, and this was more expensive, to train good ones into them.
Adult dogs were generally working animals in that area and just killing them for something that could be fixed was wasteful.