just some stuff i found on the web that may be of interest to people....heavy reading alert!!




Metabolic bone disease (MBD) has become a very important issue in the lizard market over the last few years. MBD is defined as a syndrome including a range of bone diseases associated with metabolic diseases, e.g. secondary hyperparathyroidism, rickets and osteoperosis. It is generally a chronic, or long-term result, or combination of a dietary deficiency of calcium or vitamin D, a negative dietary calcium to phosphorus ratio or the lack of exposure to ultraviolet light. A less common cause includes disruption of vitamin D metabolism due to kidney, liver, intestinal, thyroid or parathyroid disease.
The disease is most commonly seen in young growing lizards without adequate calcium (Ca) supplementation or inadequate ultraviolet (UV) lighting. Adults, especially gravid females are also at risk.
Diagnosis of MBD is primarily made from dietary history and clinical signs.

Physiology:
Calcium is an important macro mineral in the body of vertebrate species. It is responsible for neurological and muscular function and normal bone formation. Bone aids in the homeostasis of blood calcium levels by serving as a calcium and phosphorus reservoir. Up to 99% of an individual’s Ca is stored in bone. Adult animals that developed normal bone or have adequate bone mass are more resistant to MBD. Dietary Ca

and P is absorbed from the small intestine in conjunction with activated vitamin D3 (1,25-dihidrocolecalciferol). After absorption these minerals are distributed via the blood to bones and teeth where it is deposited in a crystalloid form. The balance between calcium incorporation and resorption (releasing Ca back to the blood) are under hormonal control. Both calcitriol and parathyriold hormone plays a role. The dietary Ca:P ratio is also critical for absorption. A ratio of 1:1 – 2:1 is recommended. Excessive dietary Ca is excreted via the feces.
In animals the precursor of vitamin D (7-dehydrocholesterol) is taken in via the diet. By the action of UV eradication, dehydrocholesterol is converted to cholecalciferol (inactive vitamin D3) in the skin. Both the D2 (from plants) and the D3 form (from animal origin) can also be absorbed. After absorption all these forms are carried in the blood
IN SHORT Calcium (a mineral) is needed for normal bone growth, muscle contraction and nerve conduction. The only source of calcium is dietary intake. Gut absorption of this mineral is dependant on activated vitamin D3 and the ratio and interaction of phosphorus. Dietary vitamin D3 precursors are activated by UV radiation. Non-absorbed calcium is excreted via the faeces. When inadequate levels of calcium are absorbed the body uses its calcium stores, i.e. mainly bone, to keep the calcium in the blood within normal functional range. This range is needed to keep muscle and nerve functions optimum. When the bone stores are however depleted, i.e. when there are still no calcium absorption, the movement functions start to become suboptimal and the animal start to show abnormalities.

attached to a “vitamin D binding protein” (DBP) where it is transported to the liver. In the liver cholecalciferol is converted to 25-hydroxycholecalciferol. 25-hydroxycholecalciferol is converted to activated (1,25-dihydroxycolecalciferol) and another inactivated (24,25-dehydroxycolecalciferol) form in the kidneys. Under conditions that require additional calcium and phosphorus (i.e. growth or egg development) the activated form are mainly produced. 1,25-dehidrocolecalciferol aids in the absorption of Ca and P from the GIT and in the release of parathyroid hormone (PTH).

Basic metabolism of Vitamin D
Blood calcium and phosphorus levels need to be kept constant in the body. Physiological or homeostatic mechanisms are responsible for minimizing changing blood levels.
Decreased blood calcium levels (hypocalcaemia) triggers the the release of PTH. This hormone is responsible for the activation of osteoclastic activity, which ultimately causes bone resorption and the release of Ca and P into the blood. It is also responsible for the stimulation of the synthesis of 1,25-dihydrocolecslciferol which facilitates Ca absorption form the small intestine and the correction of the Ca:P ratio by increasing P excretion via the kidneys. All the mechanisms activated by hypocalcaemia and PTH release is responsible for increasing blood calcium levels to normal (eucalcaemia). Prolonged osteoclast activity my lead to a decrease in bone mass and bone weakness.
Increased blood Ca (hypercalcaemia) triggers the release of calcitonin, a PTH antagonist. This hormone inhibits Ca resorption from bone and is ultimately responsible for decreased blood calcium levels.

Dietary History:
Insects such as crickets and cockroaches have a negative Ca:P ratio and need Ca supplementation. Insects should be fed foods with high Ca, two to three days prior to being used as food (so called “gut loading”) or dusted with a suitable Ca powder just prior to being used as food. Chicken starter mash or growing mash, sometimes used as maintenance food for crickets are deficient in Ca and should be supplemented (also see the crickets section for more info). Other gut loading foods include greens and vegetables such as lucerne/alfalfa (Medicago sativa), carrots, carrot greens and parsley. Fish flakes can also be used but dusting with appropriate calcium is still necessary.
Herbivorous diets often contain little Ca and excess P. Most fruits and lettuces are low in Ca and need Ca supplementation. Many commercial reptile diets are Ca deficient. Ca can be supplemented by adding powdered calcium to the food or by adding powdered or liquid forms to water.
Clinical Signs:
Clinical signs can broadly divided into classic MBD with symptoms related to the skeletal system and hypocalcaemic MBD where symptoms is secondary to hypocalcaemia. The most common form, namely the classic form is more common in growing animals, while the hypocalcaemic form is more prevalent in adult animals. Table 1 summarizes the most common clinical signs seen with each form.
Most common clinical signs seen with classic & hypocalcaemic forms of MBD

Classic MBD Hypocalcaemic MBD
Partial to complete lack of truncal lifting Intermitted muscle tremors, seizures & tettany
Pliable mandible or maxilla
Retention of the rounded infantile skull
Lameness or reluctance to move Flaccid paresis
Kyphosis, lordosis & scoliosis
Reduced appetite (or unable to eat) & weight loss

Clinical signs will only start a few weeks after the introduction of a sub-optimal diet or husbandry flaw. The first signs to appear are usually related to the skeletal system. Affected animals may be unable to lift their bodies from the ground, may have soft, pliable jaws and bilaterally thickened fore- and hind legs. Animals may or may not show decreased appetite. These early signs are usually only observed by experienced herpers or vets. Observant keepers will also be able to recognize these changes if they are aware of the syndrome.
In advanced cases animals will show jerky movements, tremors and malformed bodies. Signs may progress to complete lameness and eventually death. Complications of MBD include bone fractures, drying of the mucous membranes of the mouth and the inability to walk or eat.
If there are any signs that may suggest MBD the animal must be handled with the utmost care to prevent fractures and injury. Veterinary diagnosis and treatment are usually indicated.
Complications Of MBD:
Fractures are the most common complication of MBD. Falling or climbing from heights that would normally pose no problems for normal calcified bones is a common cause. Drying of mucous membranes of the mouth due to inability to keep the mouth close and inability to walk and eat are also commonly seen. Egg production may also be affected in females.
Diagnosis & Treatment:
When any of the clinical signs are seen the animal should immediately be treated by a reptile friendly vet or an experienced herpetologist. One recommended treatment is parenteral calcium administration repeated as described by the vet. Treatment can be life saving. The diagnosis can be made on the history of inadequate calcium supplementation and/or insufficient exposure to UV radiation and clinical signs alone, no radiographs are indicated. The prognosis depends on the severity and the future cooperation of the owner. In early cases where supplementation and husbandry are improved the outcome is usually favourable.
Husbandry:
Calcium can only be optimally absorbed in the presence of activated vitamin D3 and/or adequate ultraviolet (UV) radiation. UV rays (are part of a group of rays, collectively known as the light spectrum. The three groups important here are UV rays, visible light rays and infra red (IR) rays. The wavelength of UV rays is shorter than, and that of IR are longer than visible light. IR rays are responsible for heat transmission and visible light includes all the colours visible to the eye. Ultraviolet can further be subdivided into UVA and UVB. UVA rays are apparently needed for lizards to see optimally. UVB rays are needed for the activation of vitamin D3 and subsequent calcium absorption.
Diurnal lizards, i.e. Bearded dragons (Pogona vitticeps) and Iguanas need natural or artificial UV radiation. It is recommended that animals without the correct UV lighting should be exposed to natural sunlight for at least (preferably more than) 2 hours a day. Important things to keep in mind when exposing animals to sunlight are:
Always provide ad lib water and shade for in case animals get overheated.
Never put animals in closed containers, i.e. aquariums, desert dens, etc. in direct sunlight as it will heat up and mortalities can occur.
Never put animals outside when the temperature are not within the correct temperature range for the specific species.
Artificial sunlight can be supplied by various sizes of commercially available UV florescent lamps. It is important to use the biggest/longest possible lamp for the vivarium or container. Two important factors of a lamp is its output, indicated as a percentage or number, and the spectrum, UVA and UVB. The percentage output is the amount of rays the lamp emits. The popular percentages include 2.0 (2%), 5.0 (5%) and 8.0 (8%). Desert reptiles obviously need more radiation, i.e. 8% where in some cases tropical species can get away with 5%. Although most lamps are indicated to transmit both UVA and UVB it is important to get a lamp that at least transmits UVB. As ultraviolet lamps doesn't emit sufficient heat (i.e. IR rays), they should be used in conjunction with the correct heating. Important things to keep in mind when exposing animals to artificial sunlight are:
Use the correct fitting. Fluorescent fittings differ according to length (usually indicated in foot / ft.) or wattage.
Never use a UV fluorescent lamp for more than 6 months. Old lamps can emit cancer causing rays.
UV lamps should be mounted as close as possible to 30cm / 12" from the basking spot of the lizard.
Nocturnal lizards, i.e. Leopard geckos (Eublepharis macularius) which do not need UV radiation must be supplemented with a suitable calcium supplement including adequate activated Vit. D3. See supplementation for more info.

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Supplementation:
Supplementation refers to the addition of extra elements to a diet to make the diet more balanced. The two most important supplementation categories are calcium and multi vitamin/mineral supplements. Various commercial multi vitamin/mineral combinations are available from specialized pet shops and reptile friendly vets. It is important to note that adequate calcium supplementation is not included in multi vitamin/mineral combinations and should be supplemented separately.
The more important additions to calcium supplementation combinations are phosphorus and vitamin D3. For adequate calcium absorption and bone incorporation the calcium to phosphorus ratio should always be between 1.2:1 and 2:1. Theoretically Vit. D3 combinations are only required in nocturnal species such as Leopard geckos (Eublepharis macularius) which doesn't have UV requirements. Calcium/Vit. D3 combinations are obviously more expensive than regular calcium supplementation. Where correct UV lighting are supplied dietary Vit. D3 precursors will be converted to vitamin D3 and only calcium need to be supplied.
Calcium supplements are usually sold in a powdered form and are available from reptile friendly vets or specialized pet shops. Calcium should be supplemented at least twice a week and three times a week to growing lizards and gravid females. Make sure to read added instructions for further additions that might apply to specific supplementations.
There are various ways to supplement reptiles. Methods include dusting food, adding supplement to water and supplying ad lib calcium. As many lizard species rely more on food for their water requirements than fresh water, the recommended way to supplement calcium is by dusting its food. Both crickets and herbaceous foods can be dusted. As Leopard geckos (Eublepharis macularius) are known to lick calcium according to need, ad lib powdered calcium/Vit. D3 in a separate shallow container are adequate for supplementation.
It is important to note that calcium supplementation should not be done by gut loading crickets. Gut loading of crickets is ideal for multi mineral/vitamin supplementation, but the amount of calcium needed for adequate calcium supplementation are known to cause mortalities in crickets.
When preventative measurements is not implemented the disease is almost unavoidable. Hints that must also rise the suspicion for the disease includes:
Young, fast growing animal
No calcium/Vitamin D3 supplementation
No or incorrect ultraviolet lighting
Ultraviolet lighting installed more than 30 cm / 12 " from the main basking spot
Abnormal looking animals compared with the same species
Abnormal movement compared with the same species
Excessive leg movement when picked up
Unable to walk
Permanent open mouth
When any of these events are evident veterinary intervention might already be necessary! It is recommended to see a reptile friendly vet or experienced herpetologist as soon as possible. When no dietary history is available the diagnosis should be made by radiographs.
Treatment should commence immediately. Husbandry and dietary rectification are important and should help in the treatment of the disease.

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Signs of metabolic bone disease include hard knobs in the long bones of the legs, bumps along the vertebral column of the back and tail, softening or hard swelling of the jaw, and softening of the plastron or carapace in turtles and tortoises. All of these signs may be felt before they can be seen, making a careful physical exam important. Visible signs of moderate to severe MBD include jerky gait when walking, tremors and twitches in the limbs and muscles of the legs and toes when at rest, and shakiness when being held.
A common finding is a pliable mandible or maxillae - the jaw bones. This is the best evaluated with the mouth held open. To do this gently restrain the upper jaw and pull down on the dewlap with the other hand. Once the mouth is open, apply gentle posterior (behind) pressure (not lateral (side)) to the mandible, then the maxillae, with the index finger. Normally these bones should feel like solid bone; in small lizards the mandible may give a little laterally but should still feel solid. With MBD either jaw may feel pliable. As MBD worsens, posterior traction from the lower jaw musculature may foreshorten the mandible and an under bite develops. This is often aggravated by fibrous osteodystrophy that bows the mandible laterally.
Juvenile lizards often retain the rounded infantile skull shape of hatchlings because the skull fails to grow and lengthen.
Advanced cases of MBD include all the above signs plus anorexia and fractured bones. Severely deficient reptiles tend to be lethargic and may only be able to drag themselves along the ground. A reptile lacking the ability to lift it's body from the ground when sitting or walking often suffers from a moderate to severe case of MBD. Arboreal lizards spend all of their time on the ground as they lack the strength to grip and climb.
The earliest and most consistent sign of MBD is partial to complete lack of truncal lifting. A normal iguana lifts its body or trunk, and proximal tail, off the ground while walking or if disturbed. Early in the course of MBD, an iguana drags its pelvis and tail along the ground while walking, yet is still able to lift the front half of it's body. As MBD progresses, the lizard drags the entire trunk while walking. In advanced MBD, the lizard can no longer lift the trunk, the legs move vigorously, yet the lizard is incapable of ambulation.
Often, reptile keepers will miss some of the first signs of MBD and only realize there is a problem when the animal suddenly seems to have a lame leg or broken toes. Metabolic bone disease often makes the bones weak, brittle and spongy. Normal activities like climbing or jumping and landing hard on an object could cause a broken bone very easily in an animal with MBD.
Lameness, or reluctance to move, can result from single or multiple fractures. In iguanas, fractures are seen frequently in the proximal to midshaft femur (thigh), midshaft humerus (upper arm), distal radius (lower inside arm), and ulna (outer lower arm), and less commonly on the tibiotarsus. Distal radial and ulnar fractures can form a false joint and shift weight-bearing well proximal from the front foot. A single fracture, with or without a history of trauma, should always arouse suspicion of MBD.
Fibrous osteodystrophy generally affects the long bones or the jawbones. Often the underlying bone is fractured but stable. Superficially, the long bones look well-fleshed, even robust. However, with palpitation, the legs have a firm feel more reminiscent of bone than flesh. Fibrous osteodystrophy does not affect all bones equally or symmetrically.
Kyphosis (hump in spine), lordosis (forward curvature of the lower spine), and scoliosis (curvature or rotation of the spine- laterally) are less common and occasionally cause rear limb paresis (slight paralysis). Paresis generally improves with treatment, paralysis is a less common sequela.
Generally, there is a gradual decline in appetite and weight loss. If the jawbones are affected, the patient may want to eat but has difficulty doing so. Lack of growth or weight gain in growing lizards is another indication of MBD.
Radiographs are not essential for diagnosis but are useful to assess fractures, confirm suspicion of MBD, and serve as a basis for subsequent evaluation of the progress of therapy. Radiographically, there is an overall decrease in bone density. Poor bone contrast from soft tissue is especially notable in the pelvis and transverse processes of the caudal vertebrae. In truly severe cases, there may be little definition between bone and soft tissue. ..."
Metabolic bone disease is one of the most common nutritional deficiencies affecting captive reptiles. It is often the direct result of:
diets that are very low in calcium, and too high in phosphorus
Diets lacking bone are a common cause of MBD for carnivorous reptiles. Lizards or crocodilians fed organ meat (liver, heart, or gizzards) or meat without bone (chicken, beef or hamburger) develop MBD. This is because lean beef and hamburger have a Ca:P (calcium to phosphorus) ratio of 1:16, beef heart, 1:38. Therefore, even with CA supplementation, these products have a severely negative Ca:P ratio. Whole rodents, birds or fish have a positive Ca:P ratio because of their skeletal bones. Perhaps this is one reason MBD is extremely rare in mice eating snakes.
Insects also have a negative Ca:P ratio; therefore, insectivorous reptiles and amphibians are also prone to MBD. All insects should be fed a Ca-rich diet for 2 to 3 days prior to being used as food or should be dusted with Ca carbonate (CO3) just prior to being used as food. A more balanced diet for insectivores should include baby mice or whole fish.
Multivitamins often contain Ca but not enough to prevent MBD. Many commercial reptile diets are Ca deficient.
Often combined with improper husbandry practices such as:
keeping the animal at too low temperature ranges causing improper digestion of nutrients;
Improper lighting such as not using UVB florescent lights, or having the UVB florescent set up improperly, or using too old a UVB florescent;
And or not exposing the reptile to unfiltered sunlight on occasion.
-In addition, lack of exposure to UV light or insufficient vitamin D3 supplementation can induce MBD. UV lights are thought to be essential in basking species for photochemical production of the active form of vitamin D, which in reptiles, is believed to be cholecalciferol or vitamin D3. UV irradiation in the 290 to 320 nm wavelengths catalyzes production of cholecalciferol in mammals, and it is assumed this is also true for reptiles.
Since the ion product(s) of total skeletal calcium and phosphorus in most vertebrate species are in a ratio of approximately 2:1 it would appear reasonable that the available dietary ratio of these elements also should be in a range of 1:1 to 2:1. Simple stoichiometric chemistry predicts that an excess of either calcium or phosphorus will create an imbalance. In clinical practice, one usually finds diets containing gross excesses of phosphorus ion products. Muscle meats and many vegetables contain extremely low quantities of available calcium but are well endowed with excessive phosphorus.
When gross imbalances in the calcium: phosphorus ratio exist, the relatively insoluble salt, calcium phosphate (which is minimally absorbed from the gut), is favoured within the intestine. Excess phosphate ion can be absorbed thus resulting in hyperphosphatemia. The parathyroid glands are stimulated to secrete parathormone, thus inducing the leaching of calcium from the hydroxyapatite crystals in the mature bone matrix. As reabsorption continues, the bone is weakened and, concomitantly, is partially replaced by fibrocollagenous connective tissue. Affected bones tend to be larger in diameter with irregular outlines and a characteristically spongy consistency. Radiographs demonstrate normal medullary cavities surrounded by massively expanded cortical bone of greatly diminished radiodensity. These bones are deformed easily, and pathological fractures of weight-bearing long bones and vertebrae are common sequelae to this disorder. Ingestion of excessive dietary calcium ion products (with respect to phosphorus) is possible, but very unusual. When it does occur, the parafollicular cells or "C" cells of the thyroid gland(s) and ultimobranchial bodies are stimulated to secrete a hormone like substance, calcitonin, which acts to inhibit calcium ion resorption from hyroxyapatite, i.e.., it is antagonistic to the action of parathormone and, thus, reduces plasma calcium levels.
Plasma Ca and P levels can aid diagnosis and, more importantly, guide therapy. Early cases of MBD may or may not have a normal Ca and P levels, but as MBD becomes more apparent, plasma Ca levels generally decrease (often <8.5 mg/dl) and plasma P levels generally increase. An inverse Ca:P ratio is strong evidence of MBD. Symptomatic iguanas can also have a normal plasma ca and P levels. Keep in mind that because Ca is protein-bound, hypoproteinemia can contribute to an apparent hypocalcemia. Alkaline phosphatase is generally not dramatically elevated, and the significance of this enzyme in reptiles is unknown.
Hypocalcemic metabolic bone disease: Symptoms: intermittent fine muscle tremors, often first apparent in the digits, large muscles of the limbs and tail base, the tremors become increasingly more severe and frequent, especially with activity. If not corrected the fasciculations can progress to seizures and or tetany. ..."
Too much phosphorus in the blood can be caused by quite a few factors. The biggest factors being the animals diet, and the phosphorus content in each food item; hypervitaminousis D; Inadequate access to direct sunlight or artificial UVB lighting; and not being kept at the proper temperatures since proper temperatures will help the animal digest the food that it eats properly and thus absorb most of the nutrients in it's diet.
In addition to the typical causes of MBD (lack of Ca, vitamin D, and UV light or excess P) many conditions can cause similar symptoms such as egg production; thiamine (Vitamin B1), vitamin E or selenium deficiencies, septicemia, trauma, neoplasia, renal or hepatic disease, heavy parasite burdens and insecticide or heavy metal toxicity.
Two frequent causes of hypocalcemia are worth mentioning. The first is egg or follicle development in female iguanas. Gravid females tend to have distended abdomens and have been anorectic for days to weeks. The second is renal failure. A common cause, hypervitaminosis D, is thought to arise from over dosages of multivitamins and fortified mammalian rations, such as dog, cat or primate chow. In such cases, uric acid is often not elevated but P levels are. Kidney enlargement may be palpable cloacally or anterodorsal to the pelvis. Dyschezia, and less commonly, stranggiuria may be present from kidney enlargement within the pelvis. Most of these patients are depressed and eating less but not obviously polydipsic.
When there is an imbalance of calcium in the diet (hypocalcemia or hypercalcemia) bones become weak and spongy. The affected bones will also enlarge, and have irregular outlines i.e. bumps and swellings. These bones will deform easily and may also fracture easily. As the calcium levels in the blood drop muscle tremors, tetany, and or asthenia occur. When the calcium level becomes critically low death from cardiac failure may occur.
Vitamin D3 (derived from exposure to ultraviolet B), calcium (dietary and matter recycled from the bone matrix) and phosphorus (dietary) interact together to perform a number of functions besides bone growth and maintenance, including muscle contractions and blood coagulation (Wright, 1993). The result is a well-functioning system, with calcium restored to and, in the case of growing animals, added to the bone matrix. Too much phosphorus can throw this process off, as can too much or too little vitamin D3 or too little access to ultraviolet B wavelengths. As the dangers of calcium deficiency become more widely known, there is increased risk that pet owners may add too much calcium to their reptile's diet. This results in hypercalcemia, a condition as fraught with peril as is hypocalcemia.
It is possible to have a condition where there is too much calcium in the blood stream, this condition is known as hypercalcemia:
Control of serum or plasma calcium levels is mediated by parathormone, calcitonin, and vitamin D. Normal serum calcium values for reptiles vary among the species, but generally range between 8 and 20 mg/dl. ... Protein, calcium, and magnesium blood values may increase prior to egg production in female reptiles. Blood calcium values increase significantly (two to four-fold) in female reptiles exhibiting active folliculogenesis, where mobilization of calcium from bone results from increased estrogen activity.
Latrogenic hypercalcemia (i.e. serum calcium values > 40 mg/dl) is a common disorder of captive reptiles and results from excessive dietary calcium and vitamin D. Other less common causes or considerations for a hypercalcemia include primary hyperparathyroidism, pseudohyperparathyroidism, and osteolytic bone lesions. Hypocalcemia would be expected with nutritional imbalance of calcium, phosphorus and vitamin D.
In other words- hypercalcemia- if it's going to occur, usually results from too much calcium and vitamin D in the diet, or occurs in a female in a follicular stage of egg development. Hormonal or dietary causes mainly.
UVB florescent lights sold in pet stores and some health food stores such as reptisun, vitalight or iguana 5.0 produce UVB light in the 290 to 310 nm range. If your reptile is diurinal (active during the day, such as a water dragon or an iguana) you need this kind of lighting to ensure your animals health. You need this kind of light to help your reptile use the calcium in the diet properly. UVB lighting from an artificial source such as one of the tubes mentioned above, or from direct unfiltered sunlight helps the reptile make vitamin D2 in it's skin, which in turn is converted to an active form of vitamin D3. This self created vitamin D3 helps the animal use the calcium in it's diet efficiently.

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The tube should be set up so that there is NO glass or plastic between the light and the reptile as these materials block the vital UVB rays. The light should also be set up so that it is no more than 10 or 12 inches above the reptile as it is most effective at that range. UVB florescent tubes only produce UVB light for 6 to 12 months. Even though they still produce UVB light, the UVB becomes greatly reduced with use as it nears a year of age. I recommend replacing UVB florescent lights every 8 to 12 months.
As always, if outside temperatures permit, getting a healthy reptile, or one that might have calcium deficiency outdoors for some exposure to sunlight is one of the best forms of therapy for the animal. If you take your reptile outdoors it should either be held securely in your hands, or in a screened cage. Never leave a reptile outdoors in a glass tank as it could easily overheat in the sun. Any outdoor cages used for reptiles should have good ventilation and a shady area so that the animal might have a chance to thermoregulate if it does become too hot. The shaded area might also make the reptile feel more secure when outdoors. 15 to 30 minutes of sun once or twice a week is recommended for a healthy animal, daily exposure would be best for one suffering from known or suspected calcium deficiency.
If the temperatures are too cool in your area to actually take the animal outdoors for some sunlight, you might try to set up a basking area in front of a sheltered (from wind) screened window. Place a heating pad in the window sill, and set up a basking lamp to warm the area and set your reptile in front of the window in the sunlight for a short while. Please make sure the window screen is secure. Metal screens are best.
What kind of vitamin and mineral supplements do you use, how often do you offer them, and do they say they are phosphorus FREE or that they have added phosphorus?
Many species of reptiles are fed insects as the sole or as an extremely high percentage of their diets in captivity. IF the animals diet consists of a high percentage of insects, which are already high in phosphorus, it is extremely important to make sure that any vitamin or calcium supplement that you are giving your animal is PHOSPHORUS FREE. Why add to the problem?
It would be much better if all the foods we could offer our animals were higher in calcium than they are in phosphorus, but unfortunately it's usually the other way around with the food item often having twice the amount of phosphorus to calcium.
When I recommend supplementation, I recommend calcium (Phosphorus FREE of course) either daily or every second day, and vitamin supplements no more than once a week. I've never recommended giving vitamins on a more frequent basis.
If the reptile keeper is feeding a well balanced diet, providing UVB lighting or direct sunlight, proper temps, calcium supplementation daily or every second day, and vitamin supplements NO MORE than once a week then the phosphorus level can not possibly be raised due to vitamin supplementation alone.
If however someone is giving vitamins (especially one with added vitamin D3 and phosphorus) on a daily or every second day basis, then yes, it's possible that the blood phosphorus level will be too high, particularly if combined with a mainly insect diet.
Vitamin D3 is a fat soluble vitamin. It is made naturally in the skin of most animals and it helps the animal use and digest the calcium in it's diet properly. An animal getting a well balanced diet, and UVB light or direct sunlight should not need vitamin D3 supplements in it's diet. It will be making enough of this important vitamin on it's own.
If it is getting vitamin D3 supplements or too much vitamin D3 supplementation the D3, being fat soluble, can build up to toxic levels in the animals system.
Hypervitaminosis D produces soft tissue calcification. Vitamin D intoxication has followed ingestion of rodenticides containing cholecalciferol. Clinical signs in mammals are depression, anorexia, polyuria/polydipsia (frequent urination/excessive thirst), and weight loss. Treatment regimens for reptiles have not been tested by controlled clinical trials; currently, treatment should follow guidelines for other species, which often include glucocorticoids and calcitonin.
It's always a good sign if the animal is alert, an even better sign if it's active and eating on it's own, no matter what the suspected health problem might be. Reptiles rarely show that they are ill until they are extremely ill. By that time there is little time to do something to help them. Any behaviour changes in your reptile should always be noted as a possible sign of illness - from lessened appetite down to lessened activity, lethargy and poor colour.
If your reptile has reached an adult size it might be of breeding age. Female reptiles can develop eggs even if they have never mated before- the eggs just won't be fertile. Please keep this in mind if your reptile is of adult size/age and begins to not eat well and exhibit signs of calcium deficiency. It could be gravid. Egg development uses up a lot of calcium .... and many female reptiles do develop calcium deficiencies at this time.
If your reptile has developed calcium deficiency there has to be something wrong with the husbandry (unless there is a hormonal cause). Lighting, diet and proper temperatures all go hand in hand towards maintaining the health and proper calcium balance in our reptiles ... if something is off slightly such as too low temps it won't matter how well you are doing the other things, this could be enough to throw everything off for the animal. So please check out everything that I've mentioned above as something is probably off.
It is very important that the reptile have proper medical attention. Diagnostic tests such as drawing blood to test the calcium and phosphorus blood levels and ratio or taking an Xray to check for possible fractures, eggs and to check the bone density can all help determine if the animal has a calcium deficiency and how severe the problem might be.
A veterinarian will most likely send you home with liquid calcium and instructions for proper dosage. The dosage for liquid calcium is 1 mg/kg twice a day. Of course if the animal has fractures those will need to be dealt with as well and the animal might have splints or a cast applied to a limb, or even screws surgically placed into the bones if the animal has a very bad fracture. If the case of calcium deficiency is severe the vet might also give the animal injections of calcium, and or calcitonin.
It is unlikely that you will be able to determine the severity of the calcium deficiency on your own. Nor will you have access to injectable calcium or calcitonin if your reptile needs it. I strongly suggest taking your reptile to a reptile veterinarian if you suspect calcium deficiency. There are links below that will help you find a reptile vet in your area.
Along with proper medical care, it is important that you do check that the cage temps are correct, that you have the UVB florescent tube set up properly, that you try to keep the animal closer to day time temperatures at night so as to boost the immune system and metabolism, provide a proper diet with calcium carbonate powder supplementation, and that if the outside temperatures are 70 F or higher that you try to get the reptiles outside once or twice a week (daily if possible) for 15 to 30 minutes at a time for exposure to unfiltered sunlight. You can also set up the animal in front of a secure screened window for exposure to sunlight if it's too cool to take the reptile outside.

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It is said that animals are what they eat. In the case of insectivorous reptiles and amphibians it is simply not enough only to feed the correct prey, but the correct preparation also plays a role in the health of these animals. The most commonly seen metabolic abnormality in herptiles, namely Metabolic Bone Disease (MBD) is because of inadequate preparation of feeder insects prior to feeding. To prevent this disease, and other metabolic disorders, the nutritional value of commonly fed insects should be increased. The two main methods to increase the value of feeder insects are by gut loading and dusting.
Gut Loading:
Gut loading is the process where feeder insects are fed vitamin and mineral rich foods prior to feeding to other animals. It can either be done by adding gut loading foods to their current rations or by only supplying gut loaded foods. Gut loading should take place 24 to 48 hours prior to being used as food.
Dusting:
Dusting is simply the process of coating the outer part of feeder insects with powdered mineral and/or vitamin mixtures. A few feeder insects can be mixed up in a plastic bag or bottle with a pinch or two of the desired mixture. Excess powder is gently shaken off and the insects are immediately fed after coating before they have the chance to clean themselves.
Mixtures:
The most important mineral to lizards is calcium (Ca). Most insect maintenance food such as grains and cereals are deficient in Ca and should be supplemented. When it comes to the correct metabolism of calcium, the calcium : phosphorus ratio (Ca : P) is also important. The ratio should be in the region of 1.2-2 : 1. Calcium is best given in combination with vitamin D3, especially to basking lizards where ultraviolet (UV) lamps or natural sunlight is indicated, but not supplied, or to nocturnal lizards where UV requirements are not indicated. In the absence of UV light, vitamin D3 aids in the uptake of calcium and phosphorus. When UV eradiation is present vitamin D3 can be produced from dietary vitamin D precursors.
Where vitamin D is given in its inactive form (colecalciferol), it will be converted to the active form 1,25-dehydrocolecalciferol) via the kidneys. Because vitamin D is a fat soluble vitamin it can accumulate in the body where it may cause vitamin D toxicity (hypervitaminosis).
It is important to note that most multivitamin combinations do not have enough calcium for Ca supplementation and should be used in conjunction with a suitable Ca source
Calsup® (8% calcium) or calcium hydroxide, available from veterinarians or pharmacies, can be used as a general calcium dusting powder for most herptiles. They may also be used in combination with other vitamins and minerals to increase calcium levels of gut loading foods. General mineral mixtures are not adequate for calcium supplementation meaning that calcium supplementation should be done separately. Commercial and other dusting powders are available from a specialist pet shops or reptile friendly vets.
The frequency of supplying minerals depends on the type of animal. Most minerals are supplemented 2 to 3 times a week (calcium usually 2 times a week and 3 times a week to gravid and growing herptiles). Supplement requirements for each species is mentioned on their specific care sheet.
Gut Loading Mealworms:
Mealworms can be gut loaded by adding high levels of vitamins and minerals to their substrate. It might be necessary to move the desired amount of worms to a smaller container.
Dusting Mealworms:
Larvae or beetles can be dusted. Where calcium is supplied ad lib, for example to Leopard geckos, larvae can simply be put out in these containers. gently shaken up with the mineral-vitamin powder placed in a container with a lid or in a plastic bag. Make sure to shake off the excess powder.
Gut Loading Crickets:
Many crickets that are commercially available are indicated as gut loaded. It is not always clear weather these crickets are gut loaded prior to packaging (meaning they are theoretically only of value up to two days after purchase) or are fed gut loaded foods in the containers they are sold in.
Various greens and vegetables such as lucerne/alfalfa (Medicago sativa), carrots, carrot greens and parsley can be fed as gut loading foods. Fish flakes can also be used but dusting with appropriate calcium will still be necessary. Calcium, Ca-combinations or other mineral and vitamin combinations for gut loading can be bough from specialist pet shops or reptile friendly vets. Different mixtures of calcium with different concentrations are available. Calsup® (containing about 8% calcium) can be used in gut load mixtures or as dusting powder. Never feed crickets total gut loading mixtures with more than 8% calcium as it will cause increased mortalities.

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Cheers for posting that HABU - there's some really useful stuff in there if you can get your head around all of the science!

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it points out that over doing supplements can be just as bad as under doing it.

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Some great information in there - perhaps this one should be stickied Thank you for posting, Habu.