Metabolic Bone Disease, also referred to as “MBD,” is defined as a bone disorder, causing soft, brittle, weak and/or porous bones, and irregular shell growth when referencing tortoises and turtles. All reptiles can suffer from MBD. While irregular growth on the shell is the most obvious, many more problems lie under the surface, because all bones are affected.
MBD is a common problem in captive tortoises, especially in those who are young and still growing. It is caused by a combination of issues: Insufficient natural sunlight (and therefore, inadequate intake of Vitamin D,) and an insufficient diet. Diets high in phosphorus and low in calcium and other trace elements, and improper temperatures in the captive environment are all contributing factors.
One of the most common visible signs is called “pyramiding,” which refers to an uneven “stacking” of the scutes (the bony keratin sections, and bone layer beneath) rather than smooth growth resembling the Egyptian and Aztec pyramids.
This tortoise has been provided with adequate, full-spectrum sunlight, a diet high in calcium, low in phosphorus, oxalates, and plant proteins.
It’s diet consists entirely of weeds, grasses, wildflowers, and occasional treats such as mulberry leaves and rose petals.
A small but very shallow water pond (which can be made by sinking a large plant saucer level with the ground) is provided for drinking and soaking. For tortoises that burrow, the importance of an adequate burrow cannot be stressed enough. Burrows provide differences in temperature, as well as humidity, which are also necessary for proper growth and good health.
Sadly, the result of inadequate diet and care can have devastating consequences. Deprived of natural sunlight, the proper vitamins, minerals, trace elements, and fed an unhealthy diet containing harmful items leaves tortoises in pain, and suffering from severe, often irreversible illnesses. Pyramiding and Metabolic Bone Disease doesn’t stop with what we see on the “outside.”