17/08/2026
I had a really interesting conversation earlier about metabolic bone disease, and it got me thinking about how often we describe MBD as simply “a calcium deficiency” without explaining what’s actually happening inside the animal.
So, what is MBD doing to the skeleton?
MBD is a general term for problems affecting how the body manages minerals and maintains healthy bone. In reptiles, it’s commonly linked to inadequate calcium, vitamin D3 and/or UVB, but nutrition, growth, kidney function and other factors can all play a part.
Your reptile needs calcium in its blood for much more than just bones. It’s also important for muscle contraction, nerve function and other essential processes.
If the body can't get enough usable calcium from the diet, or can't absorb it properly, it still has to maintain those blood calcium levels. One way it can do this is by taking calcium from the skeleton. Basically, the bones become a calcium reserve.
Bones aren't dead structures, they’re living tissue that's constantly being broken down and rebuilt. Osteoclasts break down old bone, while osteoblasts build new bone. Normally, these processes stay balanced.
With a long-term mineral imbalance, more bone can be broken down than is replaced and properly mineralised. Over time, this can leave bones softer, weaker and less dense, potentially causing deformities, fractures and abnormal growth.
Where does UVB come in?
UVB allows the skin to produce vitamin D3. The body then converts this into active vitamin D, which helps regulate calcium and phosphorus and allows the intestine to absorb calcium from food efficiently.
UVB -> vitamin D3 -> calcium absorption -> healthy bone
(And this is exactly why our kits don't skimp out on UVB 😉)
If that process isn't working properly, simply adding more calcium isn't necessarily going to fix the problem. You can have plenty of calcium in the diet, but if the animal can't absorb and use it properly, you still have a problem.
It’s a whole system involving diet, UVB, vitamin D3, calcium absorption and mineral regulation.
Understanding the why behind reptile care is so important. MBD isn't just a wonky jaw or soft bones, it’s what happens when the systems maintaining a healthy skeleton can't keep up, often long before we can see the damage.
Ps This baby beardie is perfectly fine, they just wanted to have their photo taken!
