Texans defensive lineman Christian Covington is in the NFL concussion testing protocol, according to sources not authorized to speak publicly.
Covington left practice early Thursday morning when he walked off under his own power and didn't return.
The former sixth-round draft pick from Rice will continue to be evaluated under NFL mandatory guidelines governing concussions.
Covington recorded two sacks and eight tackles in 15 games as a rookie. He's competing for a starting job at right defensive end with Devon Still after former starter Jared Crick signed a two-year $4 million contract with the Denver Broncos this offseason.