I found a Shih Tzu a couple months ago, and brought it home on a Thursday. Brees is a cat eater. The first night, she "tasted" the critter while I was holding him (trying to get in the house), so we kept them separated. She drooled at the door and frantically tried to get I with us. We introduced in small doses, keeping the muzzle on Brees, but letting her see and sniff him. By the time we found his people (Sunday?), they were totally fine with each other. I wouldn't have let them run loose together, but the little guy could play with a squeaky while Brees slept on the sofa.
I never expected that Brees would be able to adjust to having a "bunny" in the house. Good luck!