The Reds lost their ace on 4/14 when Johhny Cueto experienced discomfort during his start. At first, the thought was a triceps injury, but later was diagnosed as a lat injury, which unfortunately can require lengthy recovery times if serious. As of now, there is no timetable for his return, but the Reds are speaking as though they hope it will be a matter of weeks, rather than months. I would be skeptical.
Another concern right now is the health of Ryan Hanigan's thumb, which has been bothering him for some time, and has now held him out of three straight games through Saturday the 20th. A foul tip off of his hand did not break any bones, but it may have caused ligament damage, and rest has done little to improve it so far. According to Hanigan, "I’m having problems with my thumb, it’s getting worse, not better. It’s lingering constantly, so I’m trying to calm it down." The nature of this injury, Hanigan's value to the team, and the quality of the guys who could replace him on the roster make the Reds' reluctance to DL him so far understandable. Hopefully, this injury can also help explain Hanigan's awful hitting so far this year. Trying to hit through a thumb injury would be extremely uncomfortable or painful, and could cause a change in approach to compensate, but I am speculating. Devin Mesoraco has filled in admirably in the short run so far.
Edit: Hanigan is on the DL with a strained oblique (OK...?), Corky Miller was recalled to take his place. Nick Masset was moved to the 60-day DL to make room on the roster for Corky. It feels like we've seen the last of Masset.
Ryan Ludwick was transferred to the 60-day DL so that Justin Freeman could be added to the roster to cover the time in between Cueto's injury and his next scheduled start. Freeman was then sent down so that Tony Cingrani could take Cueto's rotation spot.
In the minor leagues, Armando Galarraga was placed on the 7-day DL for AAA Louisville with a blister. He should not miss much more than the minimum, meaning he could return on the 23rd. Emmanuel Burriss was activated from the DL on April 19; he missed 12 days with a strained hamstring, but thankfully (please read sarcasm here) is active in time should Zack Cozart's finger injury turn out more serious than expected.
In A+ Bakersfield, first baseman Sean Buckley was placed on the 7-day DL on April 11th, and has not yet been reactivated The reason wasn't given in the transaction listing, and these things are really hard to find at the lower levels of the minors, so forgive me for not knowing the nature of these injuries.
In A- Dayton, a rash of injuries were officially handled with DL moves in anticipation of the season officially starting up. SP M.O. Wiley, 1b Carlos Sanchez, and C Nick O'Shea were all placed on the 7-day DL on April 18 with undisclosed injuries.