The book True Grit states Rooster Cogburn died from “night hoss.” What does that mean?

The book True Grit states Rooster Cogburn died from “night hoss.” What does that mean? Duff Hale Midlothian, Texas Night hoss usually referred to a sure-footed horse a cowboy preferred on night watch. You won’t find the term used to describe an affliction in standard Western Americana dictionaries, like Ramon Adams’s Western Words or Win Blevins’s Dictionary of the American West. What night hoss means in True Grit has been the subject of speculation. In the film, Cole Younger