Neither player was immediately signed to a contract.
The Bengals lost Emmanuel Lamur to a season-ending injury.
Howard, 30, tore his anterior cruciate ligament last season, but had 120 tackles for the Bengals two years ago.
Howard is a former second-round draft pick of the Oakland Raiders out of Texas-El Paso.
He has recorded 492 career tackles, six sacks, six forced fumbles and seven interceptions.
The Bengals wanted to check on Howard's medical status as he continues to recover from his knee injury.
McKenzie is a 6-foot-2, 245-pound former South Florida standout who has also played for the Tampa Bay Buccaneers.
McKenzie was a third-round draft pick of the New England Patriots in 2009, but suffered a serious knee injury.
Last season for the Vikings, he recorded 12 tackles and one forced fumble.
Follow me on Twitter: @RavensInsider
Aaron Wilson covers the Ravens for The Baltimore Sun.
This story originally appeared on Nationalfootballpost.com
- Sports & Recreation
- American Football
- Oakland Raiders
- Cincinnati Bengals
- Minnesota Vikings
- Tyrone McKenzie