Per the Bundesliga side's official website, the 24-year-old, who has not played since January 29, has been withdrawn from training "for the time being," with no specific date set for his return.
The Germany international returned to Dortmund last summer after a frustrating three-year spell at Bayern Munich and has made 11 Bundesliga appearances in 2016-17, netting one goal and providing one assist, per WhoScored.com.
Per BVB's statement, Gotze said: "I'm currently undergoing treatment and will do everything in my power to be back in training and helping my team to achieve our common goals as soon as possible."
It is another blow for the versatile attacker, whose career has stalled somewhat since his initial emergence at Dortmund under former manager Jurgen Klopp.
Gotze scored an extra-time winner for Germany in the 2014 FIFA World Cup final against Argentina. However, he never really found his place at Bayern and was used only sparsely by then-manager Pep Guardiola at the Allianz Arena in 2015-16.
His return to BVB should have been the opportunity for Gotze to once again flourish, but he has struggled in an injury-plagued first campaign back at Signal Iduna Park.
And now he is set to spend further time on the sidelines. Per Dortmund, club sporting director Michael Zorc put a positive spin on the news: "We're happy to have now uncovered the reasons for Mario's difficulties and are convinced that his extraordinary abilities will give us additional quality once he has completely recovered from this."
The Dortmund hierarchy and manager Thomas Tuchel will be eager to see Gotze recover to full fitness and sharpness as soon as possible.