It’s not just too little calcium that causes the feared MBD, it’s too much calcium and or too much phosphorus or too much vitamin D3 too!
Metabolic Bone Disease goes by the common names: Rickets, Osteoporosis, fibrous osteodystrophy, secondary nutritional hyperparathyrodism and osteomalacia. It’s a bone aching, awful disease directly related to calcium (Ca) absorption and bones. A common misconception about MBD is that it’s caused by too little calcium and or vitamin D3. It can also be caused by too much vitamin D3 or too much calcium / phosphorus. In late stages, MBD affects the bone structure. The truly horrific part about this disease is what’s happening internally before you can see visible affects of MBD. MBD affects the entire body. Maintaining a regular heart beat, blood clotting, kidney function, liver, intestine, parathyroid gland, interactions between cells and then the obvious, the skeletal structure/formation is all affected by proper calcium balance.
Two main causes of MBD: nutritional, and environmental (no UVB lighting).
Calcium interacts with phosphorus to form calcium phosphate. Calcium phosphate is essentially the bones and teeth. This process is different in every species. Which is why each species requires different amount of Calcium supplementing and some are more prone to MBD. In order for calcium to be properly absorbed into the cells it needs some assistance from vitamin D3. Vitamin D3 is formed by interaction of UVB and the skin. D3 can be obtained through natural sunlight (exposure to UVB and UVA) or through added supplements of vitamin D3 in calcium supplement formulas. If you are using UVB light it is incredibly important you alternate between Ca supplements with D3 and without D3. If you have too much calcium in the reptiles diet and not enough phosphorus this results in a phosphorus deficiency. This results in a metabolic dysfunction (MBD).
Too much phosphorus makes the calcium unusable so the body absorbs too much phosphorus that cannot be excreted by the kidneys. This results in hypocalcemia (MBD). The ideal calcium to phosphorus ratio is 2:1. Be sure to look up your pets live food nutritional information in regards to Ca:Ph ratio to avoid phosphorus binding the calcium. Oxalates also bind calcium not allowing it to be absorbed by the body. Some foods high in oxalates are spinach, rhubarb, soy and beet greens. Be aware of what you are feeding you reptile! Their nutrition is more complicated than that of a cat or dog.
Signs of MBD:
Take your pet to the vet if you’re noticing: Swollen limbs, pain or lameness, broken limbs, misshapen skeletal structure and seizures. In the beginning of MBD or calcium deficiency you may notice muscle twitching or tremors, seizures, kinked tail, lethargy or a droopy jaw.
The key to curing MBD is preventing this awful disease in the first place. More often than not, MBD permanently damages reptiles and the affects cannot be reversed.
All of my sources in this article are from a fantastic herp veterinarian, you can find her website here: www.anapsid.org