Rabbits/hares were popular animals among the Romans, they were frequently used in hunting as prey. Ferrets would have been thrown into rabbit burrows to drive them out ready for the hunt to begin. For Pliny the Elder, rabbits were placed in the category with dolphins, bees and winged animals, they were neither tamed or wild, but somewhere in between (Pliny the Elder, The Natural History, 8.81). As rabbits are so fertile, they were associated with the goddess Venus but also with the goddess of hunting, Diana.
For more information about the meanings of animals in Roman art, see our relevant blog post: Animal Symbolism in Roman Art.