Portland had to play without leading scorer Kevin Bailey, who broke his nose during the opening seconds and left the game.
Hornung, who was 10 of 14 from the field, also led the Rams with 11 rebounds. Dan Bejarano also had a double-double with 10 points and 10 rebounds. Wes Eikmeier scored 14 points.
Colorado State (9-2) never trailed in the game and led 33-20 at halftime. Colorado State shot 48 percent from the field for the game, while Portland shot 39.6 percent.
Ryan Nicholas, who was 7 of 12 from the field, led the Pilots with 15 points. Riley Barker had 11 points and 10 rebounds for the Pilots (6-7).
Bailey played 33 seconds.