This might be of some use. I'm always handing copies of it out, I've copied and pasted it.
Why guinea pigs and rabbits should not live together.
Many rabbits and guinea pigs in pet shops are housed together and this leads customers to believe they are a suitable pairing.
Until recently it has been 'normal practice' to house these two species together but the advice from most expert sources is - DON'T DO IT! If both animals are to be given the best standard of care it quickly becomes apparent that a rabbit and guinea pig pairing is not ideal. Pet shops get away with selling the two animals to live with each other as they are dealing with baby animals that will live co-operatively together while young but problems are likely to arise as the rabbit reaches maturity. Rabbits are best kept with their own kind. They have different needs to those of guinea pigs
Diet. Guinea Pigs cannot create their own Vitamin C, therefore their pelleted diet needs to enriched with Vitamin C. Rabbits can produce their own Vitamin C so their diet is lacking extra Vitamin C therefore it is unsuitable for guinea pigs. Both rabbit and guinea pig pellet diets are made to suit the individual diets of both different species, mixing these diets or feeding to the wrong species will mean the diet then lacks vital vitamins and minerals. Keeping rabbits and guinea pigs together results in a compromise of nutritional needs.
Sexual Frustration. While rabbits are not sexually attracted to guinea pigs, it does not stop them trying to hump the pig. This can be very annoying to the pig, as it is a form of bullying. When sexually frustrated, rabbits often nip and bite the victim of their frustration. A sexually frustrated rabbit will find anything suitable as a mate, a human, and guinea pig, a cuddly toy. It is worth keeping in mind 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. Bullying and unwanted attention will cause stress and guinea pigs can become ill during times of stress.
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.
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 often encounter guinea pigs whose legs have been broken after being caged with a rabbit.
Guinea pigs cannot thrive in an environment where their well-being is threatened by an improper diet, the risk of injury, foreign pathogens, and companions with whom they do not share a common language. Responsible pet ownership means providing a safe, healthy, and nurturing environment that resembles as closely as possible their natural environment. You will always find someone who swears that their rabbit and guinea get along fine. But you can't watch them 24/7 and the majority of rabbit/guinea pig owners will see their animals for approx 20 minutes each day at feeding time!
Rabswood