Vitamin D deficiency in indoor rabbits and guinea-pigs
Where do rabbits and guinea-pigs get Vitamin D from?
Vitamin D3 is only found in animal products so as herbivores, rabbits and guinea-pigs need the sun (specifically UVB rays) in order to synthesise Vitamin D3 which is needed to break down calcium.
Vitamin D enables the absorption of calcium from the intestine in small quantities which is then excreted by the kidneys. If this does not happen kidney stones and bladder stones can form. However, some of the calcium is always retained by the kidneys meaning that an overdose, (which can be found in pellets), of Vitamin D can act the same way as a deficiency, causing the kidneys to store more.
Window glass absorbs UVB which is essential for the formation of D3, this means that rabbits and guinea-pigs need direct sunlight with no glass in the way, for at least 10 minutes daily. However, they can store D3 for up to 6 months, so if your animals are only indoors during the winter, they can get by with only occasional direct sunlight (UVB rays). UVA rays travel through window glass so ensure that your animals get some sunlight into their enclosure, as UVA rays are important for the immune system and metabolism.
How does this work with indoor animals?
In the warmer months, if you have a garden or balcony, you should allow your animals time outside every day in a safe run. If you cannot do this, you have four options (these work in the winter too). The first is only possible if you have large windows that open wide so as to allow direct sunlight into the room where your animals are.
The second option is a UVB spotlight/basking lamp. This type of lamp gets very hot but they do not need to be on for a very long time, an hour in the morning and an hour in the evening should be enough, along with a special holder.
Good lamp examples include:
“AIICIOO UVB UVA Reptile Heat Lamp D3 Simulate Sunlight Self-Ballasted Basking Bulb for Amphibian Promote Pets Calcium Absorption E27 220-240V (100W, Bubble Surface)” which can be found on Amazon for £29.99.
The third option is a UVB bulb. These have a lower power consumption but do need to be on for a longer time period (seasonal daylight hours). They also do not get warm and can also be installed into normal light sockets such as a cheap desk lamp. Wires can be protected using a garden hose.
“Terra Exotica Compact Desert 10.0 UVB” found on Amazon for £17.82.
“Exo Terra Reptile UVB200 High Output Bulb 25 Watt” on Amazon for £21.34.
UVB lamps/bulbs can double the Vitamin D3 value in blood in just 14 days with no side effects. Choose lamps/bulbs recommended for animals from desert regions with a high UVB value. Make sure to look at the distances and the corresponding UVB levels. You should not go any higher than 270 μw / cm2 and the light should only be in part of the enclosure. Also they must be changed every 6 months to a year depending on the manufacturer.
The last option is artificial vitamin intake in the form of drops. This is only temporarily useful and should not be practiced long-term, as overdose can have severe health consequences as we talked about in the why pellets, nuggets & museli are not part of a healthy diet article. Additionally, UVB rays also fulfill other functions in the body and are much more valuable.
Sources:
Bourdeau, JE, Schwer-Dymerski, DA, Stern, PH, & Langman, CB (1985): Calcium and phosphorus metabolism in chronically vitamin D-deficient laboratory rabbits. Mineral and electrolyte metabolism , 12 (3), 176-185.
Brommage, R., Miller, SC, Langman, CB, Bouillon, R., Smith, R., & Bourdeau, JE (1988). The effects of chronic vitamin D deficiency on the skeleton in the adult rabbit. Bone , 9 (3), 131-139.
Fairham, J., & Harcourt-Brown, FM (1999): Preliminary investigation of the vitamin D status of pet rabbits. The Veterinary Record, 145 (16), 452-454.
Harcourt-Brown, FM (1996): Calcium deficiency, diet and dental disease in pet rabbits. The Veterinary Record, 139 (23), 567-571.
Harcourt-Brown, FM, & Baker, SJ (2001): Parathyroid hormone, haematological and biochemical parameters in relation to dental disease and husbandry in rabbits. Journal of Small Animal Practice, 42 (3), 130-136.
Jekl, V. (2013): Rabbit dental disease and calcium metabolism-the science behind opinions
Kamphues J., Carstensen P., Schroeder D., Meyer H., Schoon HA, Rosenbruch M., 1986. Effects of increasing calcium and vitamin D supply of calcium metabolism of rabbits. J. Anim. Physiol. a. Anim. Nutr ., 56, 191-208.
Lebas, F. (2000): Vitamins in rabbit nutrition Literature review and recommandations
Mitchel, A. et al (2014): Effects of ultraviolet radiation produced from artificial lights on serum 25-hydroxyvitamin D concentration in captive domestic rabbits (Oryctolagus cuniculi). American Journal of Veterinary Research or http://avmajournals.avma.org/doi/abs/10.2460/ajvr.75.4.380?url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org&rfr_dat=cr_pub%3Dpubmed& (as Dec. 2014)
Watson, M. (2014): Evaluating the clinical and physiological effects of long term ultraviolet B radiation on guinea pigs (Cavia porcellus) and rabbits (Oryctolagus cuniculus). https://www.ideals.illinois.edu/handle/2142/50499 (as of: Dec. 2014)
https://www.kaninchenwiese.de
