title ?

Spoilers:

The movie is on dvd and available from netflix. The title refers to horses being shot if they have a broken leg, and because the movie is about a dance marathon, and the marathon, which is a metaphor for the desperation of life in the 1930s, the dancers are exhausted. At the end of the movie, one character hands a gun to another and asks to be shot. When the murderer is being taken away in the paddy wagon, the final line is "They shoot horses, don't they?"

Try and see it. This is a terrific movie that hasn't dated unlike many of those from the same period like Bonnie and Clyde or The Sterile Cuckoo.

Simply stated, he put her out of her misery as a benevolent act.

You would do it for a suffering animal, why not for a suffering person. It was probably also commentary on how little value human life had in that time in that situation.