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The most discussed topic when it comes to UVB for reptiles is vitamin D synthesis. In simple terms, when a reptile is given access to UVB, they can create their own vitamin D3 in their skin which is further transformed into 25-hydroxyvitamin D3 by the liver. From this point, it can then enter the bloodstream and enable the reptile to metabolize calcium from their diet. Metabolizing calcium is essential for bone, muscle, and nerve health. If calcium cannot be absorbed from the gut, the calcium will be pushed out of the animal’s bones by the parathyroid, leading to metabolic bone disease or MBD(ref. 1). MBD can cause severe deformities within reptiles, such as a crooked spine or limbs, fragile bones, seizures, and in the worst cases even death(ref. 2). Most reptile keepers know they should provide UVB lighting as well as calcium supplements in the reptile’s diet to avoid the development of MBD, but what other benefits can UVB provide our scaly friends?
Besides aiding the production of vitamin D3, UVB exposure can also help regulate the immune system, and act as a disinfectant on the surface of the skin while simultaneously strengthening the skin barrier functions of the animal(ref. 3). In humans and other mammals, exposure to UVB has shown an increase in positive feelings(ref. 4). While it is currently unknown whether reptiles also experience positive emotions while basking, it is something worth considering alongside the physical health benefits of using ultraviolet light.
What about Nocturnal Reptiles?
UVB is considered essential for proper husbandry when it comes to diurnal and basking species of reptile, but is frequently deemed optional for nocturnal and/or crepuscular species. For example, leopard geckos are often cited as reptiles that can live healthy lives by using calcium supplements with vitamin D3 instead of a UVB light. However, while these small lizards can still experience the internal benefits of vitamin D3 from the powdered supplement, they inevitably miss out on the previously mentioned skin and immune system benefits of UVB. Secondly, by providing a reptile with a UVB light instead of powdered vitamin D3 supplement, we are allowing them to self-regulate their exposure. This reduces the risk of overdosing or under dosing the reptile, as they can then synthesize their own vitamin D3 as they need it. To continue using leopard geckos as an example, when provided with UVB, many of them will engage in a behaviour known as cryptic basking- exposing a part of their body, such as their leg or tail, while sleeping. Although this behaviour doesn’t look anything like a bearded dragon basking, both species are still benefiting from the surface effects of UVB while synthesizing vitamin D3.
Are there any dangers with using UVB lighting?
There are some precautions that should be considered when using UVB lighting with reptiles, such as ensuring the bulb is from a reputable company to avoid the potential of harmful waves being emitted (some of the most popular companies include Arcadia, ExoTerra, and ZooMed)(ref. 3). UVB lights should be placed a minimum distance away from the animal to prevent potential burns, which will be mentioned on the box of the bulb. Over time, these bulbs will emit less UVB and need to be replaced. Depending on the brand of the bulb, this can range from once every 6 months to once per year. Lastly, every animal has a Ferguson zone, which describes how much UVB they would be exposed to in their natural habitat. The chosen UVB bulb should correspond with the animal’s appropriate Ferguson zone so they can comfortably utilize the lighting system(ref. 5).
References:
1. Divers, S. J. & Stahl, S. J. (2019). Malder’s Reptile and Amphibian Medicine and Surgery (3rd ed.). Elsevier.
2. Metabolic bone disease (MBD) & disorders in reptiles. PetMD. (n.d.). Retrieved April, 2023,
from https://www.petmd.com/reptile/conditions/musculoskeletal/c_rp_hyperparathyroidism
3. Animals at Home. (2021, Sept. 26). Do ALL Reptiles NEED FULL Spectrum Light? Dr.
Frances Baines [Video]. YouTube. https://www.youtube.com/watch?v=EhbDx11OMfM&t=3s
4. Veleva, B. I., van Bezooijen, R. L., Chel, V. G., Numans, M. E., & Caljouw, M. A. (2018). Effect of ultraviolet light on mood, depressive disorders and well-being. Photodermatology, Photoimmunology & Photomedicine, 34(5), 288–297. https://doi.org/10.1111/phpp.12396
5. Baines, F., Chattel, J., Dale, J., Garrick, D., Gill, I., Goetz, M., Skelton, T., & Swatman, M. (2016, January 31). How much UVB does my reptile need? The UV-Tool, a guide to the selection of UV lighting for reptiles and amphibians in captivity. View of how much UVB does my reptile need? the UV-tool, a guide to the selection of UV lighting for reptiles and amphibians in captivity. Retrieved April 2023, from https://www.jzar.org/jzar/article/view/150/89