The 32-year-old right-hander suffered a broken finger on his pitching hand in early March after accidentally shutting a door on it.
Cook, a veteran of nine major league seasons with Colorado, went 6-8 with a 5.08 earned run average in 23 starts last year. He owns a career mark of 69-58 with a 4.41 ERA over 220 games (189 starts).
In other club news, lefty Jorge De La Rosa was transferred from the 15-day to 60-day DL after undergoing Tommy John surgery on his left elbow on June 3.
He tore the ulnar collateral ligament on May 24th and is lost for the remainder of the season.
De La Rosa, 30, compiled a 5-2 record with a 3.51 earned run average in 10 outings this year.
The Rockies also optioned right-hander Greg Reynolds to Triple-A Colorado Springs on Wednesday.
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