Slay was not at the open portion of Wednesday's practice.
Shead had initially signed with Detroit during free agency in March and had appeared to be slated to be the starter opposite Slay at the beginning of training camp. He eventually was passed on the depth chart by Nevin Lawson and then Teez Tabor.
A strained quadriceps also kept him out of two preseason games. Shead played a lot in the preseason finale. At the time he said he asked for the heavier workload in a game usually reserved for players on the roster bubble or likely to be cut, but then days later he was released by the Lions.
A former starter in Seattle, Shead has made 154 tackles in his career with 24 passes defended. When the Lions initially signed Shead, they gave him $1.5 million in guaranteed money. By cutting him earlier this month, the team saved $1,631,250.