I have noticed lately that people are housing their guinea pig and rabbit together. This is something that should never be done. The first reaction to those who do house them together is, "but they get along fine". Maybe they do, that is not the issue. The issue is they have very different needs. Also, rabbits are very strong. Whether its intentional or not, they can seriously injure a guinea pig.
Please read the provided information.
"Diet. Although guinea pigs and rabbits are both herbivores who eat primarily hay, they require different nutrients and consume different quantities. For instance, guinea pigs need a regular supply of Vitamin C, which they get both from their daily vegetable intake and specially-formulated pellets. Guinea pigs should NOT eat rabbit pellets, as these are formulated to meet the rabbit’s digestive needs only and do not contain extra Vitamin C. In addition, some rabbit pellets, designed for use by breeders and labs, contain antibiotics that are potentially harmful to guinea pigs."
"Size and strength. Even the smallest dwarf rabbit can pose a physical danger to a guinea pig, especially if space is limited. Rabbits often kick or stomp with their powerful hind feet when they are expressing their emotions. Whether a rabbit is jumping for joy or thumping out of annoyance, a guinea pig stands a good chance of getting hurt. This is not as uncommon as you might think. Rescuers and other concerned animal welfarists often encounter guinea pigs whose legs have been broken after being caged in a pet store with a rabbit. Such injuries often require surgery and a lifetime regimen of anti-inflammatory medication."
"Immunity. Most animals carry organisms which are not harmful to them but which can be fatal to other species. In the case of rabbits, a very common bacteria found in their respiratory tract is Pasteurella. While antibiotic treatments can control this disease, it often lingers on in a carrier state and requires occasional treatment. Rabbits can live a long life as carriers of Pasteurella and not even show any symptoms. However, guinea pigs are highly susceptible to respiratory infections, and their fragile immune system is not equipped to battle this pathogen. If exposed to Pasteurella, a guinea pig is many times more likely than a rabbit to succumb to the organism and die. It is a chance that not many of us would like to take with our beloved pets."
"Social Life. Have you ever watched two rabbits together? They like to snuggle and groom each other constantly. Guinea pigs, on the other hand, do not groom each other on a regular basis. Nor are they habitual cuddlers. Instead, they like to maintain their own personal space and don’t often like to share. In this kind of environment, a rabbit could become very lonely and a guinea pig might start feeling harassed. Keep in mind, then, that rabbits and guinea pigs are quite different animals, one of them desiring a close, affectionate bonded pair, the other sharing a more limited interaction with a herd."
I urge you to read over this story of a guinea pig and a rabbit.
Guinea Lynx :: Topic - Guinea pig injured by rabbit