The thing about HUD that no one has ever given it credit for is its sensitivity to animal suffering. Animals suffer and die in westerns. It's a fact that was - and still is - rarely spent any time in. But HUD sees and hears their suffering. It's all over the movie.

The jerk of the cow's neck as it's locked in place so it can be injected with disease. The squeal of the greased pigs as they scramble away from the men. (SPOILER) The terror and chaos in the pit before the cows are slaughtered.

It wasn't uncommon for westerns of this era to show sensitivity to the suffering of horses. But horses are companion animals, much like dogs. They're domesticated. HUD takes the time to notice the feelings of cows and pigs. I can't think of a western since that has done the same.