Calcium metabolism and Vit D in rabbits

The subject of calcium metabolism, and Vitamin D provision in rabbits (either via the food, or produced by the body in response to sunlight on skin), is not fully understood. Rabbits are crepuscular, and tend only to come out of their burrows in late afternoon/early evening, and return just after dawn. As a result, especially in the UK, which is not their natural environment, and receives less sunlight than Europe, where they originated from, they do not become exposed to high levels of ultraviolet radiation. One study, published in 1999, showed that largely hutch bound rabbits had significantly lower Vitamin D levels than rabbits with ad-lib access to a run. For that reason, amongst many others, hutches are not enough. Indoor rabbits are a more complicated issue. Standard glass does not permit significant amounts of ultraviolet radiation to pass through it, and so indoor rabbits should be similarly deficient to hutch bound rabbits, if this were the only source. However, diet is another source. Selective feeding leads to avoidance of less favoured items, which are often the ones containing vitamin and mineral supplementation. Extruded or compressed pellet diets should be better than this. Sun dried hay is also a good source. however, the exact requirements for dietary vs sunlight produced vitamin D are not fully understood. Whilst indoor rabbits may benefit from exposure to sunlight and fresh air, in an open or mesh topped run, for many reasons, its not currently possible to show that they lack sufficient Vitamin D, without further studies. This also means that at present it is difficult to suggest a suitable amount of time that they should be outside. Its also not currently certain what the effect of any lack of Vitamin D is, as the rabbit is very effective at absorbing Calcium from the diet without it, when dietary calcium levels are reasonable. For these reasons, the best advice we can give is to allow, where possible, and without subjecting the rabbit to too many changes of scene, access to a safe, spacious, and partly sheltered outdoor run area, as part of an outdoor set up. And with indoor rabbits, if possible to do so without subjecting them to contrasting extremes of temperature, to do the same. All rabbits should be fed ad-lib hay and water, and a carefully controlled amount of pelleted food, plus a handful of green leafy vegetation, unless they have particular dietary needs. If your rabbit has problems eating hay, you are advised to visit your vet for a dental examination