The Cowboys safety depth continues to thin.Veteran safety Jeff Heath left in the second quarter vs. the Seahawks for an X-ray on his left ankle after getting tangled and stepped on in Dallas' game at Seattle. Heath was initally evaluated on the sideline before medical personnel sent him off for an X-ray.Cowboys safety Kavon Frazier needed medical attention in the first quarter for a shoulder injury after an illegal-block penalty on Seattle cornerback Neiko Thrope.Cowboys safety Xavier Woods returned Sunday for his first game since a preseason hamstring injury."The concern coming into the season for the Cowboys was safety play," Fox's lead color analyst Troy Aikman said on the broadcast.