Snyder left after the second inning of Wednesday night's Pirates-D-backs game after sliding into second base in an attempt to stretch a single into a double. Snyder underwent tests later on Wednesday night.
Snyder missed time in Spring Training with low back pain and began the season on the DL.
The two catchers now on the Pirates' roster, Dusty Brown and Toregas, were Nos. 4 and 5 on the depth chart at the beginning of the season, behind Snyder, Ryan Doumit and Jason Jaramillo.
Doumit fractured his ankle on May 29 and is not expected to return until late July, at the earliest. Jaramillo has been on the DL in Indianapolis since being hit on the elbow with a pitch during the second week of May. He is not expected to return to the lineup soon.
Pirates manager Clint Hurdle said the Pirates would explore outside options for another catcher, but did not elaborate.