Howell hasn't practiced in more than two weeks after injuring his neck. He spent part of this week seeing a specialist in Minneapolis to determine how best to proceed with treatment.
The safety also missed 10 games last season with a neck injury.
"Anytime there's anything with a neck, you have to cross your t's and dot your i's," Colts general manager Ryan Grigson said earlier this week. "That's a serious area. It's something that's been nagging him. He's going through the whole entire process of seeing multiple people so he can formulate that opinion with his wife and his agent and himself and us and make the decision that's best for Delano."
An undrafted free agent originally signed by the Buffalo Bills in 2012, Howell was signed by the Colts late in the 2012 season and has been with the team since.
- Ben Estes