Metabolic Bone Disease (MBD) in Leopard Geckos
| Root cause | Calcium/D3/phosphorus imbalance |
| Reversible? | Manageable, not fully reversible once deformed |
What causes it
MBD develops from a sustained imbalance between calcium, phosphorus, and vitamin D3 — usually from inadequate calcium supplementation, an unbalanced feeder diet, or (for D3) inadequate UVB or dietary D3 for the gecko's needs.
Early signs
Subtle signs include reduced activity, a slight tremor in the limbs, or reluctance to move normally — these are easy to miss and are why regular handling and weighing helps catch changes early.
Advanced signs
As it progresses, signs become more obvious: a soft, rubbery lower jaw, bowed or bent limbs, a kinked or swollen tail base, and difficulty walking or lifting the body off the ground.
Treatment and outlook
A vet can prescribe calcium and D3 supplementation and correct any underlying deficiency, and mild cases often improve significantly with treatment. However, bone deformity that has already occurred generally does not fully reverse — this is why prevention through correct supplementation is far more effective than treatment after the fact.
See the full care guides guide, or browse all 593 info pages.
A single adult leopard gecko needs a 20-gallon long tank as an absolute minimum, with a 36x18 in (40-gallon breeder) footprint now considered the recommended standard — plus a secure lid, an under-tank heater on a thermostat, a thermal gradient, at least three hides, and a shallow water dish.
Set up in this order: substrate, then heat source wired through a thermostat, then hides and water dish, then decor — and run the whole enclosure for at least 24–48 hours to confirm stable temperatures before your gecko moves in.
Hatchlings can start in a 10-gallon tank or tub, juveniles do well in 20 gallons, and adults need a 20-gallon long as an absolute minimum — with 36x18 in (40-gallon breeder) now the widely recommended standard, not just an upgrade.
Heat a leopard gecko enclosure with an under-tank heater and/or overhead heat source (halogen or deep heat projector) wired through a thermostat — a thermostat is mandatory, not optional, and heat rocks should never be used.
Leopard geckos can survive without UVB using dietary D3 supplementation, but current husbandry guidance now recommends low-level UVB (roughly 2–6% T5) as best practice — it improves D3 synthesis, bone density, and natural behavior, and views on it have shifted significantly from older nocturnal-species advice.
Keep ambient humidity around 30–40% across most of the enclosure, with a dedicated humid hide raised to roughly 70–80% to support smooth, complete sheds.