Ruggiano's move, retroactive to August 23, is due to left ankle inflammation, while Sweeney is hampered by a left hamstring strain.
To fill the roster slots, the Cubs recalled outfielder Jorge Soler and infielder Logan Watkins from Triple-A Iowa.
Soler, ranked as the No. 49 overall prospect by MLB.com prior to the season, will make his major league debut in Wednesday's game against Cincinnati. The 22-year-old Cuban has hit .340 with 15 home runs, 23 doubles, 57 RBI and a .700 slugging percentage over three minor league levels in 2014.