Keeping reptiles, snakes, lizards and chelonians is popular and growing. The order of the reptiles comprises over 11000 species, but I still will use this term during this presentation for the sake of convenience.

Unfortunately knowledge about the most commonly kept species is often inadequate. Many reptile species are sold in pet shops at ridiculously low prices and as a result they are often impulse purchases.

It is essential that people know exactly what species of reptile they are buying. Only then can the animal be properly provided for with regards to optimal housing and feeding.

For example, green iguana's (Iguana iguana) originate from South America, bearded dragons (Pogona vitticeps) from Australia, Asian water dragons (Physignathus cocincinus), and monitor lizards (Varanus spp.) from Asia or Africa. In the wild all of these species are exposed to higher levels of UVB radiation (290–310 nm) than in captivity. UVB radiation in the correct amount and wavelength is essential for the production of vitamin D3 in the body. The regulation of calcium metabolism is under hormonal and vitamin influences (vitamin D3, calcitonin, parathyroid hormone). Vitamin D3 regulates the oral uptake of dietary supplied calcium. The cascade in the activation of vitamin D3 consists influence of sunlight, especially UVb radiation on the skin and hydroxalation in liver and kidney. UVb converts 7–dehydrocholesterol to an inactive vitamin D3 molecule (cholecalciferol). In the liver this is hydroxylated to 25-hydroxycholecalciferol or 25-hydroxy vitamin D3 (further on referred as 25(OH)D3). The kidney will hydroxylate it in to the active 1,25(OH)2D3 or the inactive 24,25(OH)2D3.

Furthermore, in captivity the animals are fed diets consisting of fruits, vegetables and/or insects. These foods are low in calcium, high in phosphorous and very low in vitamin D. The combination of insufficient UVB radiation and low calcium and high phosphorous intake leads to generalized metabolic bone disease. Low blood calcium values in pregnant adult reptiles leads to dystocia, or the death of the female shortly before or during oviposition/birth of young. Eggs may be very friable and young may die just before pipping. Even if the young do hatch they may have skeletal malformations.

Furthermore, when the exact species, and thus the temperature of the natural habitat is not known, the environmental temperature in captivity may be inadequate. Keeping tropical animals at too low temperatures can be detrimental for metabolic and physiological processes in the animal. For example, snakes that are kept at too low temperatures do not digest their prey properly, and may vomit.

Clinical and pathological presentation of metabolic bone disease will be presented and discussed.