Lonesome Dove, Volume 1 by Larry McMurtry

ONCE THEY GOT WEST, beyond the line of the grasshopper plague, the herd found good grass, the skies stayed clear for nearly two weeks, and the drive went the smoothest it had gone. The cattle settled down and moved north toward the Arkansas without stampedes or other incidents, except for one-a freak accident that cost Newt his favorite horse, Mouse.

Newt wasn't even riding Mouse when the accident occurred. He had traded mounts for the day with Ben Rainey. The day's work was over and Ben had ridden into the herd with Call's permission to cut out a beef for the cook. He rode up to a little bridled cow, meaning to take her yearling calf, and while he was easing the calf away from her the cow turned mean suddenly and hooked Mouse right back of the girth. She was a small cow with unusually sharp horns, and her thrust was so violent that Mouse's hindquarters were lifted off the ground. Ben Rainey was thrown, and had to scramble to keep from being hooked himself. Soupy Jones saw it happen. He loped in and soon turned the mad cow, but the damage was done. Mouse was spurting blood like a fountain from his abdomen.