SEATTLE — Seattle Mariners All-Star second baseman Robinson Cano has been suspended 80 games for violating baseball’s joint drug agreement.

The league announced Cano’s suspension Tuesday in a stunning development for the stalwart in the middle of the Mariners’ lineup and a club expected to contend for a postseason spot in the American League. Cano tested positive for Furosemide, a diuretic. In a statement released through the players’ association, Cano says, “This substance was given to me by a licensed doctor in the Dominican Republic to treat a medical ailment.” He said he didn’t realize it was banned.

It’s the first major strike in a career that has Hall of Fame potential. Cano was trending toward being one of the few current players with a chance to reach 3,000 hits in his career and has been a consummate defensive standout. Cano is an eight-time All-Star but now must deal with the stigma of a suspension.