Some books recommend keeping rabbits and guinea pigs together to meet their social needs. While some people have seen success with this technique, the current consensus is that rabbits should never be kept in the same cage with guinea pigs. A rabbit can easily harass or injure a guinea pig; this can lead to severe distress or even death for the guinea pig. It may be unintentional or due to being startled, since the rabbit is larger and stronger so can seriously injure a guinea pig. They also have differing nutritional requirements, so it is therefore preferable that rabbits and guinea pigs are fed separately. Guinea pigs require additional Vitamin C in their diets that rabbits don’t. Lack of Vitamin C may lead to scurvy.
Additionally, guinea pigs typically show very little interest in social activities necessary for the rabbit’s well-being, such as grooming; this limits the intended benefit of housing the guinea pig and rabbit together in the first place.
It is generally recommended that dogs should never be left alone with rabbits as their predatory instincts (or overenthusiastic play) can lead to the dog attacking the rabbit spontaneously. Cats, on the other hand, can become close and safe potential companions if properly introduced to the rabbit and they are of at least roughly equivalent size. In fact, when the cat is introduced in a home with a resident rabbit, the rabbit sometimes will act aggressively to establish his territory and the cat, which does not have such concerns, will typically cede the point to the resident.
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