Slugs can level tiny tender beet shoots completely. I would recommend looking for them, with a flashlight in hand, at night.Here is an article that will tell you how to deal with garden slugs:
https://www.gardeningknowhow.com/plant-problems/pests/insects/kill-garden-slugs.htm
As for rabbits - how high up is your raised bed? It is recommended to build a bed that is at least 18 inches high to discourage rabbits. Here is an article outlining some strategies to keep rabbits away from your garden:
https://www.gardeningknowhow.com/plant-problems/pests/animals/keep-rabbits-out-of-gardens.htm