Purdy (right elbow) didn't practice Thursday, Nick Wagoner of ESPN - Serving Sports Fans. Anytime. Anywhere. reports.

Purdy hasn't officially been ruled out for the 49ers' season finale Sunday at Arizona, but his lack of activity so far this week forecasts the likely outcome for the third-year signal-caller, especially after coach Kyle Shanahan said Wednesday that Joshua Dobbs would get the start under center. As a result, Friday's injury report may confirm Purdy's lack of availability for Week 18 action after emerging from this past Sunday's loss to the Lions with a contusion and nerve inflammation in his right throwing elbow.