Navarro, who's batting .276 with one home run and 16 RBIs, is permitted to be away from the club for between three and seven days while on personal leave.
"We'll see who's pitching," Gibbons said of which catcher will play which days. "Thole has been pretty good at the plate, and Kratz has been pretty good too."
Kratz, a right-handed hitter, entered Wednesday hitting .231 with two homers and six RBIs in 11 games for Toronto this season.
Thole, who hits from the left side, was .375 (15-for-40) in 17 games entering Wednesday. He catches whenever knuckleballer R.A. Dickey starts, and typically logs extra time behind the plate when Navarro needs a day off.