The Bonanza episode where the horse dies?

There's an episode of the show where Joe buys this really expensive horse because of its breeding and is really proud of it. Something happens where people get hurt and he's forced to make a shortcut up a mountain or large hill of some kind that is previously known to be impassable for horses because the strain kills them. The horse makes it over the hill and down the other side and dies after Joe is able to fetch help for the injured person. Which episode is that?