One thing that is crucial to keeping reptiles and amphibians (and most taxa) in captivity is the provision of supplements. Whilst we can effectively simulate the light and heat from the sun, grow geographically sound plants in our enclosures and provide realistic photoperiods, rain cycles and humidity gradients, we cannot perfectly replicate an ecosystem’s total biological tapestry. It would be impossible to provide the wild diet of most reptiles and amphibians, let alone provide the correct elements to build the intricate macronutrients within that diet. Short of harvesting wild bugs and risking the health of our captive animals, herpetoculturists must provide calcium, as well as various vitamin and mineral supplement/s to give their animal the healthiest food intake.

The heart of husbandry

Poor nutrition is the leading cause of illnesses in captive reptiles and amphibians. However, this is not as straightforward as providing the wrong supplement. Lighting, heating, humidity and other environmental factors influence how well our animal’s function biologically, including how well they respond to supplements.

UVB radiation from the sun allows for Vitamin D synthesis which then helps to absorb calcium for the development of healthy bones. Previously, metabolic bone disease caused by lack of UVB was extremely common the hobby. In the wild most reptiles would take in calcium within their natural diet or feeding habits and sunlight would provide adequate UVB radiation. Of course, this differs across species. Species who are typically exposed to less UV are generally more capable of synthesising vitamin D3 supplements through their diet, with MBD being a bigger issue for sun-worshipping reptiles such as bearded dragons and green iguanas. We know now that all reptiles benefit from UVB lighting, and this helps them synthesise vitamin D naturally as opposed to excessive supplementation.

Calcium & D3 overdosing

Calcium is a mineral that is necessary for life. As well as a plethora of blood and muscular benefits, calcium is most famous for helping bones grow strong. In addition to calcium, reptiles will also ingest many other essential minerals and vitamins. One often overlooked mineral is Magnesium, which is essential for bone development, regulating muscle and nerve function, blood sugar levels, blood pressure and making protein. Most calcium supplements on the market today have a combination of both elements, to ensure optimal bone development.

Mediterranean tortoise species such as hermanns (T. hermanni) or marginated tortoises (Testudo marginata) would naturally source their calcium from a variety of methods. In the wild, they would typically be found grazing on shrubs and grasses which grow in calcium rich soils, thus containing a high level of calcium. Cacti such as ‘prickly pears’ offer up a high concentration of calcium, making them a preferred snack for these species. As well as ingesting small amounts of limestone, tortoises are known to chomp on snail shells and skeletons of dead animals to ensure their calcium needs are met.

Other species such as veiled chameleons (Chamaeleo calyptratus) would generally require less calcium in their diet but be exposed to high levels of UV and prey that are covered with calcium-rich dust present in the arid limestone environments that they inhabit. This is where supplementation gets a little trickier. Providing a vitamin D3 supplement, alongside strong UV radiation can cause certain species to synthesise vitamin D too much and lead to hypervitaminosis D. This then opens the flood gates for excessive calcium absorption and can cause problems within the intestines and kidneys as they are calcified, leading to further health complications.

Luckily, many brands have already developed products to cater for this. Zoo Med, Reptile Systems and Exo-Terra have already launched calcium and vitamin supplements without D3. This means that a combination of ‘with D3’ and ‘without D3’ can be used to ensure the perfect balance. In fact, many keepers using good quality UVB lighting will almost always opt for a vitamin/calcium supplement without D3 and use other supplements only if an animal requires it (such as being in a quarantine, or health assessment situation). Ultimately, science-backed species-specific research should be undertaken before any supplements are provided, but keepers should be aware that this research is only just catching up with the huge product development advances that have happened in recent years.

It should also be noted that vitamin D is technically a hormone. Animals will know how much vitamin D they require and thus adapt their UV exposure accordingly. If an animal has the choice to move away from a UVB light source, it can stop the amount of vitamin D it is synthesising and thus avoid an overdose. If a UVB and the heat source are combined and the spot is not warm enough, it forces the animal to spend too long underneath and absorb excessive UV, which then converts calcium into a harmful level of vitamin D.

Yemen chameleon (*Chamaeleo calyptratus*)

Carotenoids and vitamin A

Some supplementations can come from the foods we naturally provide to our animals or their prey. Beta-carotene is a type of carotenoid found in orange and yellow plant matter and leafy greens (carrots are a great example). When ingested naturally, these can be formed into vitamin A which is a key component in ensuring healthy epithelial tissue (surface layer skin) and is vital for growth, vision and reproduction in many species. However, vitamin A is extremely easy to overdose and can cause a lot of health complications if not provided correctly.

Carotenoids and Beta-carotene in particular, can be successfully converted to vitamin A naturally with absolutely no risk of overdosing in herbivorous reptiles. The body of many species such as bearded dragons will convert Beta-carotene into the required amount of vitamin A and excrete any excess in their waste. Feeding carotenoid-rich vegetables as well as feeder insects that have previously fed on carotenoid-rich vegetables is fine.

Other species do not convert beta-carotene into vitamin A very well. It is widely believed that most dart frog species struggle greatly with this conversion and must instead be supplied with a preformed vitamin A supplement (usually Retinol) to receive adequate nutrition. However, this should only be used very occasionally. Most suppliers of this type of product would label the correct portions and feeding schedules to ensure that animals do not overdose.

Other carotenoids are found in everyday multivitamins. Paprika and turmeric are chocked full of these pigments and are brilliant antioxidants which help develop the immune system of our pet reptiles and amphibians. Species specific research is required for keepers to ensure they are providing the very best spectrum of vitamins in minerals.

Gut loading

The nutrient profile of insects varies across species, but also across individuals. It is possible to understand the average amount of protein, fat, calcium, phosphorous, ash and trace elements of a certain species but this research is usually based on an insect having eaten a good diet within 48 hours of being analysed. Therefore, the feeder insects we buy from the shelves of pet shops, whilst often provided with some food source, will have most likely lost a lot of nutrients before they make it home to your animal. This is where gut-loading comes in.

Gut-loading formulas are available from various brands, ProRep do a range of bug grubs, hydration balls, gels, jelly pots and various other booster products to keep feeder insects as nutritious as possible. Fresh foods, especially carrots should be fed as a supplement to ensure that feeder insects are packed with nutrients, but ensure they are peeled and washed to reduce the risk of pesticides. Pet owners who only keep one animal and generally get through just a single tub of live food each week are more likely to see this process as a bit of a faff but keeping a schedule and maintaining feeder insect health underpins the nutrients a beloved pet receives in the long term.

Supplement storage

Every supplement that is comprised of various vitamins and minerals will eventually expire. Although this is unlikely to harm your reptile or amphibian, the concentration and effectiveness of the vitamins and minerals will slowly diminish. Although each product will have a slightly different shelf life, most will find their potency degrade after a year or two. For keepers working with lots of animals, this is rarely a problem but bulk-buyers looking to care for a single pet might find themselves with supplements passed there best before date. If this is the case, it needs replacing.

Tips to preserve supplements include: keeping the supplement refrigerated, avoiding any moisture or humidity getting into the container and avoiding direct sunlight. Supplements should also never be fed to feeder insects, as certain species will metabolise certain vitamins differently, leading to potentially harmful imbalances. Instead, use a branded gut-loading formula as insect food. Finally, try to replace opened supplements every 6 months. Usually, the expiry dates on these products will be years away, but this is generally on the basis that the product is unopened and refrigerated. The average user should replace their supplement much more frequently.

This should also be noted for the foods of other taxa. For example, Psittacus’ complete diets are formulated to such specific quantities of the correct amounts of every vitamin, mineral and trace element, that they can be sun sensitive. Leaving any formulated animal food or supplement in incorrect conditions can alter the product very slightly, which undermines the extensive research behind the recipe. If in doubt, throw it out.

The EK Guide to Supplements

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