Horst, 29, spent 2014 with Triple-A Lehigh in the Phillies system, going 4-2 with a 3.98 ERA in 45 games, including three starts. The left-hander struck out 57 and walked 31 in 63⅓ innings for the IronPigs last year.
Horst saw major league action in parts of three seasons with the Reds and Phillies from 2011-2013, putting up a 3.34 ERA in 72 games, all in relief, with 70 strikeouts and 32 walks in 72⅔ innings. In the majors he has held left-handed batters to hitting .241/.336/.352, with a 24.6-percent strikeout rate, and in the minors in 2014 held lefties to hitting .236/.286/.427 with a 24.5-percent strikeout rate.
The Reds originally drafted and signed Horst in the 21st round in 2007. He was traded from Cincinnati to Philadelphia for old friend Wilson Valdez in January 2012.
The minor league deal for Horst does not include a non-roster invitation to Dodgers big league camp in spring training, though that could change now that fellow southpaw Robert Carson had his non-roster invitation to camp rescinded by the team after his 50-game suspension for a drug of abuse on Tuesday.
As of now, the Dodgers will enter big league camp in spring training with six left-handed relief pitchers in camp — Daniel Coulombe, J.P. Howell, Adam Liberatore, Paco Rodriguez, Ryan Buchter and David Huff.