Metabolic Bone Disease in Chameleons

What is it?

Metabolic bone disease, also called fibrous osteodystrophy, is a very common condition in common chameleons kept in captivity. It results from an imbalance between calcium, phosphorus, and vitamin D3 in the body. This imbalance gradually weakens the bones, which become soft, deformed, or brittle. It is one of the main causes of death in poorly cared-for chameleons in terrariums.

Commonly observed signs

These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.

Causes and risk factors

The main cause is a lack of calcium in the diet, often worsened by excess phosphorus or insufficient vitamin D3. Vitamin D3 is essential for the body to absorb calcium properly. In chameleons, it is normally produced by the skin when exposed to ultraviolet B (UVB) rays from the sun. In captivity, lack of exposure to appropriate UVB lighting prevents this natural production, even if the diet is rich in calcium. The body then draws calcium from the bones to maintain a normal level in the blood, gradually weakening them.

The main risk factors are a terrarium without UVB lighting specific to reptiles, a diet consisting only of insects not supplemented with calcium, and the lack of appropriate vitamin and mineral supplementation for the species. Young growing chameleons and breeding females, whose calcium needs are higher, are particularly vulnerable. A poorly positioned terrarium, an old or incorrectly positioned UVB lamp also increases the risk.

Diagnosis and care

Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.

Treatment

Management combines immediate correction of diet and lighting, appropriate calcium supplementation, and sometimes vitamin D3 under veterinary supervision.

In severe cases, supportive care including hydration and assisted feeding may be needed.

Fractures or major deformities may require immobilization or specific clinical treatment.

No self-treatment should be undertaken without veterinary advice, as excess calcium or vitamin D3 can also be harmful.

Prevention

Possible complications

Complications include spontaneous fractures, permanent deformities of the spine or limbs, inability to feed properly due to jaw deformity, and digestive or respiratory problems related to ribcage deformity.

In severe untreated cases, the outcome may be fatal.

When to see a veterinarian

Prognosis

The outlook depends on the stage of disease at the time of diagnosis.

Caught early, the disease can be stabilized and partially reversed with prompt correction of the environment and diet.

In advanced cases with significant deformities or multiple fractures, the outlook is more guarded and lasting damage may persist throughout life.

Without treatment, the condition is often fatal.

Frequently asked questions

References

AVMA — American Veterinary Medical Association

Content reviewed by the TunisieVet editorial team · Updated 01 September 2026