Most rabbit caregivers find their rabbits are happier with a companion. In our experience, rabbits have strong opinions about the choice of companion; therefore it is best to let the rabbit chose his or her friend. HRS maintains a “dating service,” where you can bring your bunny and let him/her meet eligible rabbits; we have extensive experience in uniting couples. Bunny must be spayed or neutered to prevent fighting. There is nothing cuter than two bunnies washing each other, or hanging out side by side, yin-yang style. Plus your rabbit will have a companion to share while you are asleep or at work. Two rabbits are no more work than one, and are definitely twice the fun!
Alternatively, rabbits interact with other animals; rabbit/guinea pig pairs are not uncommon. Rabbits and cats often get along well, provided the latter is an indoor cat; similarly, we have placed many rabbits in homes with well-trained dogs who accept bunny as part of the pack. Quite often it is the rabbit who becomes the boss of the house!