Allen left Sunday's game against the Texans with an ankle injury, and he was ruled out for the rest of the night shortly thereafter, Kevin Bowen of Colts.com reports.
Allen accounted for the Colts' first two targets of the game, but he couldn't make it through the first quarter, and it didn't take long for the team to rule him out. Jack Doyle already plays a lot and is now left as the top tight end, with Erik Swoope serving as the backup. Should Allen miss any further time, Doyle might find himself in an every-down role, potentially absorbing a good chunk of his teammate's targets (five per game). Neither tight end has individually topped six targets in a game this season, but they did combine for at least nine in four out of five games entering Sunday.