Perkins started 29 games in goal for the Timbers this season, recording nine clean sheets, while Horst made 16 appearances for the club with 11 starts.
Timbers general manager/technical director Gavin Wilkinson also announced that the team has exercised the contract options for 16 players, while declining the contract options for goalkeeper Adin Brown, midfielders Rodrigo Lopez, Peter Lowry and Ryan Pore and forwards Spencer Thompson and Brian Umony.
After today's moves the Timbers are left with 22 players on their roster:
Goalkeepers (2): Jake Gleeson, Troy Perkins. Defenders (8): Eric Brunner, Mike Chabala, Futty Danso, David Horst, Lovel Palmer, Steve Purdy, Chris Taylor, Rodney Wallace. Midfielders (8): Eric Alexander, Kalif Alhassan, Freddie Braun, Diego Chara, Jack Jewsbury, James Marcelin, Darlington Nagbe, Sal Zizzo. Forwards (4): Kenny Cooper, Bright Dike, Eddie Johnson, Jorge Perlaza.