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Metabolic Bone Disease. A triangle of events.

Subject: Metabolic Bone Disease. A triangle of events.
by longhairedgit on 1/11/2007 15:59:14

So what is metabolic bone disease? In literal terms its the decalcification of bones and internal organs and sometimes skin in reptiles. Basically brittle bones and deformity, often painful, equivalent to severe osteoporosis in humans, only much more pervasive and wider in its scope of effect on the reptilian body. This is not a contagious disease, or a pathogen, but an environmental ailmet caused soley by inappropriate keeping conditions. To be specific three parts of care, the diet, the temperature, and the availability of vitamin d3. The keeper is ALWAYS at fault.

If any one of these factors is wrong, or missing, a reptile will fall victim to MBD. All factors, heat , vitamin d3 in the diet and a calcium/ phorspherous ratio suitable for the species, are part of a metabolic chain, and without them the animal will invariably fall victim. Sometimes it takes weeks, sometimes it takes months, and sometimes it takes years, but it does happen. Most captive reptiles in the UK will probably suffer from this awful keeper inflicted disease at some point in their lives, and many may die , unless the keeper is understanding of the following facts and procedures. Knowing these is not an option, it is an absolute necessity, and the fundamental basis of good herpetoculture. To ignore it , is quite simply to inflict a potentially debilitating and lethal illness on your pet reptile.

Synthesis of vitamin d3.

All reptiles need to either ingest vitamin d3, or synthesise it from the food they eat or the UVB frequency in sunlight they are exposed to. Diurnal lizards all need vitamin d3 synthesis to happen from exposure to sunlight or correct frequency bulbs designed specifically for the purpose. Daylight bulbs and fishtank lights will not do. There are very few species who are an exception to the rule, and they are often in the desert skinks, who have massive uv filters in their skin and scales,or specialised jungle floor dwellers. These are very rare in the hobby and very few of you will be keeping those. So if your lizard is diurnal , you need to be paying attention to this bit.

Diurnal reptiles have a layer of fat within the skin on their dorsal surfaces, within these layers are reagents that when working with sunlight produce vitamin d3. Vitamin d3 is an essential vitamin that allows the reptile to reassign calcium absorbed from digestion into its growing structures like bone, teeth scales etc, and without this exposure or a reasonable dietary equivalent added in supplements ( and compensating dietarily is not a very safe way to do it, hypocalcaemia is a real possibility) without it the reptile will begin to use up calcium, and become brittle boned, deformed, with joint stiffness , spinal curvature, jaw deformities and eventually a long and unpleasant death.

To date, striplights manufactured by zoomed are the only ones I could wholeheartedly recommend for giving a remotely acceptable range of light frequency, and even then the animal must have close exposure at some time during its 12-14 hour photoperiod. This exposure must not be interrupted by glass or perspex, the light must hit the animal directly, and usually within the range of 18 inches or less. The uvb component in the frequency of light we need has a short range, and bulbs should be replaced every 6 months to a year. You will probably have to mesh the bulb off. Blacklights conversely should only be used for short exposures, no more than 2 hours a day, even for desert species, and they often damage eyes and skin, and I cant wholeheartedly recommend them.

UVA ranges in bulbs provide no direct health benefit, but often normalise a reptiles behaviour , making it less likely to become depressive. The same applies to tortoises and turtles kept indoors. Reptiles are responsive to light ranges that humans cannot see, and without appropriate lighting various organs like the pineal eye will not be stimulated normally, and the reptile may percieve itself to be in an eternal lack of sunlight, and reptiles respond seasonally with brumation behaviours. Lacking uva can make a reptile confused about its status and this leads to depressive behaviours like refusal of food.

Genuine actual sunlight is the best thing there is. If you can, take your lizards, tortoises, and turtles outdoors in summer, in containment tubs, large reptiles can be handled and held, and you can build outdoor mesh cages for them to use when temps break 75f. Those few days a year of natural sunlight exposure can be real lifesavers, even if you do have uvb bulbs. Expect aggression and flight behaviours though, exposure to real sunlight can have a truly marked effect on a reptiles behaviour. A real "call of the wild" effect.

Nocturnal reptiles generally dont benefit from UVB, although reptile bulbs will do them no harm, and might help to mentally adjust them . Photoperiod is still important for nocturnal species.

Snakes generally dont need sunlight uvb, they have a cleverr way of metabolising their vitamin d from the livers of their victims.

Vitamin supplementation.

In the uk , where a vast selection of natural foods is difficult to come by, and most of our ground plants arent grown in chalky soils, being that most reptiles that require high dietary calcium actually come from areas that were once part of the tethys sea in prehistoric times. We in the uk do not have access to such calcium rich land and forage, so in our reptiles it is necessary to vitamin supplement our reptile pets. In the wild iguanas, tortoises etc eat literally hundreds of different plants, and chucking a few salad foods at them is not a reasonable substitute.Insectivores and predators too, would in nature eat a diverse range of insects, literally thousands of different species,all the insects eating different calcium rich diets, and they too will not survive on a monotypic diet of crickets, so you must use supplementation.

For herbivores like iguanas, uromastix, and tortoises, and even some of the larger mature agamids, and turtles that take a significant proportion of vegetable matter as they age, you must ensure that the calcium /phospherous ratio is at least 2:1. You can be less specific with insectivores, although their food by contrast, (crickets , mealworms, waxworms, pinkies etc, should all be dusted periodically, soetimes every day for young or weak animals already showing signs of mbd, to every other day or once a week depending on age , size, and food intake.

Feeder insects have to be fed before you give them to your reptile! Usual choices include oranges, potato, chinese leaf, cabbages, squashes etc, some people even use fishfood, which might be useful to some of you, although it should be noted that most crickets fed with fish flakes tend to bloat out in hours, and die, so you have to give them to the reptiles very fast when you do that. The bran insects come with does not count as quality nutrition.Most insects arrive in your hand nutrient depleted.

With insects some people prefer to dust, other prefer to gut load, over the years I usually have done both, sometimes together, sometimes in rotation to avoid vitamin imbalances. Foods high in oxylates , such as cabbage, sprouts , greens etc, may cause an excess of tannins and oxylates. When ingested these oxylates bind calcium carbonate into calcium oxylate, and the reptilian body cannot absorb that. If you give the reptile too many oxylates in its diet, you negate the effect of giving it dietary calcium, making supplementation pointless. Things like taking the skin off bananas completely ruins their calcium phospherous ratio.If the phospherous ratio is too high, yet again , calcium does not get to the bones. There are many if and buts, so make sure you know the nutritional breakdown of the foods you offer.

Snakes may need additional supplementation, but not as much as lizards or tortoises. If something gets dusted or dipped in reptile vitamins once in every 3 or 4 times they eat, thats usually passes muster. Some keepers avoid nutritional deficiency for years without supplements, but it is generally a good idea for conditioning purposes and to ensure sloughing of skins goes well.


The final part of the triangle. No matter how much uvb you give them, no matter how many vitamins and minerals, no matter how nutritionally rich and varied the foods, if heat is not available to the reptile if it cannot bask or warm itself on appropriate equipment, it will not metabolyse nutrition from its food, and diurnal reptiles cannot synthesise vitamin d3. The reaction simply will not take place, so make sure you know your reptiles suitable temperature ranges , and provide them religiously, and make sure there is a gradient so the reptile can go to, or retreat from heat as it wishes.

That completes the triangle. Remember them all, and memorise them , take them to heart, appreciate their seriousness, and never neglect them, and your reptile will probably never suffer MBD. Remember this is new info to some , mythic to others, and bread and butter to good herpetologists. Uk herpetoculturalists are some of the least able in the world,and you have to be very careful where you get your information from, and reptile health in this country is in a shocking state. Its essential knowledge. Please spread the word, and have a happy herpetological time of things!