If pasteurella is a concern, keep your rabbit out of direct or indirect contact with other rabbits. If you decide to add a new rabbit, she should be quarantined for at least 90 days and be examined by a veterinarian at the beginning and end of quarantine. Consider having any new rabbit tested using a combination of an antibody test and a DNA probe-based test during quarantine. Purchase young rabbits from sources that provide documentation that each bunny has been tested for pasteurella prior to sale and never return a rabbit to a rabbitry if she has been exposed to other rabbits.
For more information, please read the article Rabbit Respiratory Disease.