Vitamin D3 deficiency in reptiles
Vitamin D3 is the most important vitamin in reptile nutrition. Vitamin D3 deficiency in reptiles inhibits their calcium absorption from the gastrointestinal tract into the blood, which results in the disruption of the correct calcium-phosphorus ratio. As a consequence, their body seeks to balance this ratio by recovering the calcium stored primarily in the bones. The accompanying disease is called secondary hyperparathyroidism. It leads to the excessive secretion of parathyroid hormone, and thus to the release of calcium from the bones, which directly contributes to rickets. Symptoms of the disease include a limp jaw (it looks as if it was made of rubber), broken or deformed limbs, ribs and spine.
How is vitamin D3 formed?
Under natural conditions, vitamin D3 is synthesized during exposure to sunlight. In the skin of reptiles, previtamin D3 is formed from 7-dehydrocholesterol, which undergoes photoisomerization when exposed to UVB radiation between 290–315 nm wavelengths. Under the influence of heat, it is then converted to the inactive form of vitamin D3 – cholecalciferol. Cholecalciferol binds to plasma proteins, which are transported to the liver and converted to calcifediol.
Calcifediol is then transported to the kidneys and converted to calcitriol – the active form of vitamin D3. It is calcitriol that facilitates the absorption of calcium from food in the digestive tract. Therefore, providing calcium in the diet alone is not enough. In case of vitamin D3 deficiency in reptiles, calcium from food will not be absorbed into the blood. This vitamin can be also found in the liver and kidneys of vertebrates. Therefore, animals that eat whole vertebrates (such as snakes, monitor lizards or crocodiles) rarely suffer from deficiencies of this vitamin and rarely need additional supplementation.
What is the cause of vitamin D3 deficiency in reptiles?
Most captive reptiles are kept indoors, without access to natural light. If such terrarium is not equipped with specialized lamps that provide UVB radiation, there is a high risk of Vitamin D3 deficiency. This deficiency (due to impaired calcium absorption from food) leads directly to weakened bones, rickets, convulsions and neurological disorders.
How to prevent Vitamin D3 deficiency in reptiles?
Reptiles should have free access to UVB radiation as this is the safest way to ensure adequate production of vitamin D3. Remember, however, that UVB emission efficiency of specialist terrarium lamps decreases with time. In the case of tubular and compact fluorescent lamps, their efficiency drops noticeably after just a few months of use. For this reason, make sure to replace them regularly with new ones. Metal halide lamps are much more durable and effective in UVB emissions, but their spectrum is also depleted over time. It is worth to regularly check the efficiency of the lamps with a suitable meter.
How to supplement Vitamin D3 in reptiles?
For me, supplementation is just a way of covering up for undesirable deficiencies. It is difficult to determine the exact dose without knowing the needs of the animal, so be careful not to overdose on vitamins. Optimal solution is using products containing 20 000–60 000 IU/kg of D3, which are generally considered safe for reptiles. For reptiles that are active during the day, and live within range of good quality UVB radiation, it is sufficient to add a vitamin supplement with D3 to the food 3–4 times a month.
Meeting the needs of nocturnal species may prove more difficult as these reptiles are active from dusk to dawn and avoid light and thus do not benefit from the presence of UVB in the terrarium. In their case, use vitamin D3 supplementation more often, even every second or third feeding.
And note that herbivorous reptiles, such as tortoises and green iguanas, need most of your attention in vitamin D3 supplementation, as it is assumed that these animals have limited capacity to absorb this vitamin from food.
Which Vitamin D3 supplements are the best?
Try Tropical Vigorept Multivit. It simply and effectively provides vitamins D3 and K and other valuable biologically active substances, which are essential in the diet of reptiles and amphibians. If used regularly with Tropical Vigorept Mineral, it ensures their proper growth and development. It also supports the absorption of calcium from the digestive tract and regulates its metabolism in the body.
Tropical Vigorept Multivit prevents rickets (MBD) and deformations in reptiles and amphibians, as well as other dangerous effects of vitamins and minerals deficiency. It also prevents shell deformations in turtles. It has a high yet safe content of vitamins D3 (40 000 iu/kg) and K (1360 mg/kg).
Vitamin K is responsible for calcium resorption from blood to bone. It also contains beta-carotene which is an antioxidant and a safe source of vitamin A. The product also contains prebiotics, including beta-glucan and chicory root inulin. They are natural immune stimulators that increase digestibility, vitality and defense against infection. Thanks to the presence of spirulina, chlorella and Kelp algae, the product provides many essential amino acids,https://tropicaledu.com/authors/ fatty acids and highly absorbable microelements. The form of micronized powder ensures good adhesion of the product to the surface of food insects and plant foods.
Is it possible to overdose on vitamin D3 in the diet of reptiles?
If you provide too much vitamin D3 in the diet, there is a risk of excess calcium being deposited in the tissues, including joint tissues. This will lead to their impairment, causing pain and limiting their mobility.
Literature
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McWilliams D.A., Nutrition research on calcium homeostasis. I. Lizards (with recommendations), Int. Zoo Yb. 39, 2005, s. 69–77.
Kolb S., Nutritional Secondary Hyperparathyroidism in reptiles, Veterinary Nursing in Action (oct/nov), 2017.
Mancinelli E., Overview of common nutritional disorders of captive reptiles, Vet Times – The website for the veterinary profession, September 21, 2015, https://www.vettimes.co.uk.
Pough F.H., Recommendations for the Care of Amphibians and Reptiles in Academic Institutions, National Academy Press, 33(4), Washington 1991.
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Xie S., Low Ji Z., Vitamin A Balance in Reptiles, Conference: Singapore Veterinary Association/Asian Society of Zoo and Wildlife Medicine/Unusual and Exotic Pet Veterinarians/Association of Avian Veterinarians – Australasian Committee Joint Conference, 2013.
