Depends on what's in it. For example, some medications won't break down until they reach a certain high temperature, many parasites too. The most resilient of parasites are round worm eggs which can survive in soil and manure for years. Cold temperatures can also preserve some things more than...
It's only true if the rabbits producing the manure have a disease or parasite and the rabbit waste is raw.
If you compost it, it's fine. It's also fine if it's from your own herd as long as your rabbits are healthy. Rabbit manure from outside sources or unhealthy rabbits may contain bacteria...