Dunning is expected to fill in for starter Jacob deGrom (elbow) while deGrom is on the 15-day injured list, Shawn McFarland of the Dallas Morning News reports.
DeGrom was placed on the IL on Saturday and is eligible to return May 14. The Rangers have two off days this coming week and will need a fifth starter once during that stretch if they choose to go with four starters over the next seven days. Dunning has pitched well out of the bullpen this season and has thrown at least four innings on two occasions, so he should be able to offer the Rangers a decent amount of length whenever he's needed to make a spot start in place of deGrom.