I have rabbits and chins but we do not house them in the same room and nothing that has touched the rabbits in the past 24hrs (the lifespan outside the body of the worst respiratory illnesses) goes near the chins. I don't know exactly what the risk level is but it's been years with no problems. A lot of people keep guinea pigs and chins and guinea pigs can carry the same illness if they've been around rabbits themselves. They never show symptoms though and it doesn't spread well without snotty noses or some other method of travel. I would actually be more concerned with pet quality rabbits than breeding rabbits. Breeders have to be careful to keep the lines healthy and resistant to falling ill when exposed at shows and by other breeders. Many also practice a closed rabbitry once they get enough rabbits to establish their breeding program so nothing new that could be carrying a new strain or weak enough to succumb to illness is brought in to the rabbitry.