🦴 Metabolic Bone Disease in Reptiles: A Vet’s 2025 Guide to Nutritional Secondary Hyperparathyroidism | Dr Duncan Houston BVSc

One of the most common and preventable illnesses in captive reptiles is nutritional secondary hyperparathyroidism (NSHP), a form of metabolic bone disease (MBD) caused by improper calcium, phosphorus, and vitamin D3 levels — often paired with insufficient UVB lighting. 🦎🌞

This guide explains how to recognize, treat, and prevent this painful and debilitating disease so your reptile can live a healthy, active life. 🧠🦴

📉 What Is Nutritional Secondary Hyperparathyroidism?

NSHP occurs when a reptile doesn’t get enough dietary calcium or vitamin D3, or gets too much phosphorus. The body responds by pulling calcium from the bones, weakening the skeleton and leading to fractures, deformities, and neurological signs. 🧬

🧠 The Parathyroid Gland’s Role:

• 🧪 Low calcium → parathyroid hormone released
• 🦴 Bone calcium is resorbed to stabilize blood calcium

🦎 Species at Risk

• 🦎 Bearded dragons
• 🦎 Water dragons
• 🦎 Iguanas
• 🐢 Tortoises and turtles
• 🦎 Leopard geckos

NSHP is especially common in young, growing reptiles and breeding females. Insectivores and herbivores are particularly susceptible due to dietary challenges. 📉

⚠️ Signs of Metabolic Bone Disease

• 🦵 Swollen, hard hind legs
• 🦷 Rubber jaw or sagging lips
• 🦴 Kinked tail or spinal bumps
• 💥 Fractures, twisted limbs, or shell deformities
• 🧠 Tremors, jerky movement, seizures
• 🍽️ Difficulty eating or egg laying
• 🦥 Lethargy, bloating, constipation, or prolapse

In chameleons:

• 👅 Tongue dysfunction or tongue hanging out

📋 Diagnosis

Your vet will perform a full history, exam, and may recommend:

• 🧪 Bloodwork — calcium, phosphorus, and kidney levels
• 📸 X-rays — check bone density, fractures, deformities
• 🧬 Possible testing for infectious or toxic causes

Early diagnosis is essential for stopping progression and preventing irreversible deformities. 🧠

💉 Treatment of NSHP

1. Calcium & Vitamin D3 Supplementation

• 💉 Injectable calcium for tremors or seizures
• 🥄 Oral calcium daily for 1–3 months
• 🌞 D3 injections or enhanced UVB exposure

2. Supportive Care

• 💧 Rehydration (oral, subcutaneous, intraosseous)
• 🍽️ Syringe, tube, or assist feeding
• 🛏️ Reduce climbing or risky activity to prevent fractures

3. Fracture Management

• 🩹 Tape splints or cage rest for small reptiles

4. Monitor & Adjust

• 📆 Recheck blood calcium and phosphorus
• 📸 Repeat X-rays every 4–6 weeks

Severe cases may benefit from calcitonin therapy, which accelerates calcium return to bone. 🧠

🛡️ Prevention of MBD

1. UVB Exposure

• 🌞 Natural sunlight is best (no glass)
• 💡 UVB bulbs (replace every 6–12 months)
• 📏 Position bulbs 12–16 inches from basking spot

2. Diet Balance

Insectivores:

• 🐛 Gut-load insects with greens or balanced food
• 🧂 Dust with calcium + D3 2–3x/week

Herbivores:

• 🥬 Focus on high Ca:P ratio greens (collards, dandelion, parsley)
• 🥗 Limit fruit to 10% of diet
• 🌾 Use calcium carbonate on salads 2–3x/week

3. Housing

• 🌡️ Provide proper temperature gradient
• 📏 Ensure basking zones are not overcrowded

4. Spaying Consideration

Spaying females may prevent reproductive-linked MBD and improve longevity. 🧠

📈 Prognosis

• ✅ Good — if caught early and treated consistently
• ⚠️ Moderate — with jaw deformity or spinal damage
• ❌ Poor — if diagnosis is late or no changes are made

Some deformities (jaw or spine) are permanent, but function and comfort can improve significantly. 💚

📱 AskAVet.com for Ongoing Monitoring

Need a recovery plan or feeding guide? Download the Ask A Vet app to consult directly with exotic vets for supplementation schedules, UVB lighting help, and growth tracking. 🐾💬

NSHP is one of the most preventable diseases in reptiles. Let’s work together to stop it before it starts — and help our lizards, turtles, and tortoises thrive. 🦎🌿