In iguanas, radiographs showing demineralized bone indicate a deficiency of which vitamin?

• A. Vitamin C
• B. Vitamin D3
• C. Vitamin A
• D. Vitamin K

Answer: (B)

Calcium balance and bone mineralization hinge on vitamin D3 because it enables efficient gut absorption of calcium (and phosphorus) and supports deposition of minerals into the bone. In iguanas, not getting enough vitamin D3—often from insufficient UV exposure or a calcium-poor diet—leads to metabolic bone disease. The bones become demineralized and osteopenic on radiographs, reflecting a failure to mineralize properly due to low calcium availability.

Deficiencies of the other vitamins don’t produce this pattern as directly. Vitamin C deficiency affects collagen synthesis and can cause fragile bones, but it doesn’t typically present with the generalized radiographic demineralization seen with vitamin D3 deficiency. Vitamin A deficiency alters growth and mucosal health rather than producing this specific mineral loss on imaging. Vitamin K is involved in bone turnover and blood clotting, but its deficiency isn’t the classic cause of demineralized bones on radiographs in reptiles.