Metabolic Bone Disease

Metabolic Bone Disease (MBD) is a condition (or conditions) resulting in abnormal bone growth and/or repair. It encompasses the following conditions and syndromes; osteoporosis, osteomalacia, osteopenia, rickets, fibrous osteodystrophy, hypocalcemia and nutritional secondary hyperparathyroidism.


MBD is generally the long term result of deficient dietary calcium and/or vitamin D3. This results in a negative calcium:phosphorous ratio and is caused by the following:



The diagnosis is usually made from a dietary and environmental history as well as clinical signs.

Dietary and Environmental History

A proper diet is critical to the health of the tortoise. In general you want a diet that's high in calcium, high in fiber, low in phosphorous and adequate in protein. This is discussed in more detail in the diet sections and in the pyramiding section.

The tortoise also needs a proper environment. Without this, even a perfect diet can result in MBD.

Some critical factors are UVB and moisture levels. However too much is just as harmful as too little. To strike a proper balance, gradients are needed. The tort needs a warm basking area with UVB, but it also requires a cooler section without UVB. This allows it to not only regulate its body temperature, but to also control its UVB exposure. The same is true for moisture. It needs a warm moist area as well as a cool dry spot.

Clinical Signs:

Treatment and Prevention:

MBD is far easier to prevent than to treat. Some of the important issues are:

The above is not only important for prevention, but is also a critical part of treatment.

The following quote is from Mader in "Reptile  Medicine and Surgery" page 390:

"All the medicine in the world will not correct MBD if husbandry, especially the diet, is not improved. Treatment consists of good nursing care with respect to handling, force-feeding, and providing a balanced fortified ration and UV light. "