What does a dream about killing a mountain lion mean?

So I had this dream that my brother and I were horseback riding and stopped for lunch. I was getting lunch stuff out and had told him to take care of the horses. He had loosened their girths and had taken the bridals off with out putting their halters on first. The horses bolted so we chased after them. We were running down a dry stream bed banked with a cliff that rose strait up. A mountain lion suddenly jumped out of the foliage lining the other bank of the stream bed and attacked my brother. So I jumped out in front of him and slit the throat of the lion with the pocket knife that suddenly appeared in my hand. The lions blood splashed all over my and the corpse fell on me. Then the dream ended. What does this mean?