Metabolic Bone Disease in Reptiles

As the name suggests, metabolic bone disease attacks the skeletal system. It causes bones to become weak, soft, or easily broken, and can also lead to muscle twitching, abnormal movement, and difficulty walking. Without treatment, metabolic bone disease is painful and often fatal. 

MBD develops when a reptile’s calcium, phosphorus, and vitamin D3 levels are out of balance. This imbalance is usually caused by an improper diet, lack of ultraviolet (UVB) lighting, ​​or improper diet.  

Fast-growing juveniles and egg-laying reptiles are especially vulnerable, but all reptiles can develop MBD if their care needs aren’t met. 

Reptiles have very specific environmental and nutritional requirements, and pet parent mistakes  in their care such as an outdated UVB bulb or inconsistent supplementation can lead to serious health issues over time.  

Because MBD often develops slowly over months, symptoms may not be obvious until the disease is advanced. 

Veterinarians most commonly diagnose metabolic bone disease in lizards, turtles, and tortoises, though it can also occur in snakes and amphibians. 

If you suspect your reptile may have metabolic bone disease, contact an exotic animal veterinarian immediately.  

Early symptoms of metabolic bone disease are often vague and easy to miss. Reptile owners may notice: 

• Decreased appetite 
• Lethargy 
• Weight loss 

As the disease progresses, symptoms may include: 

• Broken or easily fractured bones 
• Soft or “rubbery” legs 
• Swollen jaw or limbs 
• Misshapen or soft shell in turtles and tortoises 
• Trouble walking or moving normally 
• Muscle twitching or rigidity 
• Difficulty urinating or defecating 
• Cloacal prolapse (tissues protruding from the cloaca) 
• Seizures 

Reptiles depend on their environment to meet their nutritional and metabolic needs. When calcium intake or absorption is inadequate, the body begins pulling calcium from the bones, causing them to weaken over time. 

Calcium plays a critical role in many body systems, including: 

• Nervous system function 
• Muscle contractions 
• Blood clotting 
• Digestion 
• Immune health 
• Hormone regulation 
• Reproduction 

The most common reasons reptiles develop MBD include: 

• Diets low in calcium or with an improper calcium-to-phosphorus ratio 
• Inadequate calcium supplementation 
• Lack of UVB lighting 
• Poor nutrient absorption due to parasites or illness 

UVB lighting is especially important. Reptiles need UVB exposure to produce vitamin D3, which allows their bodies to absorb and regulate calcium. Without proper UVB, even a calcium-rich diet won’t prevent MBD. 

Many reptile owners include calcium supplements in their pet’s diet.  

Check with your veterinarian to see which calcium supplement may be best for your unique pet. 

All reptiles can develop MBD, but it’s diagnosed more frequently in certain species, including: 

• Bearded dragons 
• Leopard geckos 
• Chameleons 
• Iguanas 
• Water dragons 
• Sulcata and leopard tortoises 

Reptiles such as snakes who eat whole prey may be at lower risk due to naturally higher calcium levels in their diet. 

Additional risk factors include: 

• Young, growing reptiles 
• Egg-laying or breeding animals 
• Chronic stress 
• Parasites 
• Poor or inconsistent supplementation 
• Inadequate UVB lighting 

​​​If your reptile is at high risk of developing MBD, an exotic animal veterinarian can help ensure their diet is balanced and enclosure is properly set up. 

Veterinarians often suspect MBD based on a physical exam and a detailed review of the reptile’s diet and enclosure setup. To confirm the diagnosis and guide treatment, they may use: 

• X-rays: Show thinning, demineralized bones, fractures, or abnormal bone growth 
• Blood tests: Often reveal low calcium, high phosphorus, and low vitamin D3 levels 
• Fecal testing: Identifies parasites that may interfere with nutrient absorption 

Treatment focuses first on stabilizing life-threatening complications, including: 

• Seizures 
• Dehydration 
• Cloacal prolapse 
• Fractures 

Once stabilized, veterinarians work to restore proper calcium, phosphorus, and vitamin D3 levels, and correct underlying husbandry issues. Depending on the cause and severity, treatment may include: 

• Oral or injectable calcium 
• Vitamin D3 supplementation 
• UVB light therapy 
• Fluid therapy 
• Phosphate binders 
• Deworming medications 
• Nutritional support or assisted feeding 
• Pain management 

There are no home remedies that can reverse metabolic bone disease once it begins. Veterinary care is essential. 

Recovery time varies based on disease severity. Mild cases may improve with treatment, while severe cases can take months and your pet may still have a poor prognosis. 

During recovery: 

• House the reptile alone to reduce stress and risk of injury 
• Prevent climbing or falling 
• Handle gently, as bones are extremely fragile 
• Follow your veterinarian’s guidance for feeding and handling 
• Provide hiding spaces to help your reptile feel secure 

In advanced cases where quality of life is poor, humane euthanasia may be recommended. 

Proper care is the best way to prevent MBD. 

Helpful prevention tips include: 

• Provide species-appropriate UVB lighting and replace bulbs as recommended 
• ​​​Maintain proper temperature and humidity in the enclosure 
• Feed a balanced, species-specific diet 
• Use supplements carefully—more is not always better. For example, too much calcium can cause kidney disease and heart issues. 
• Keep a care journal to track weight, appetite, shedding, bowel movements, and enclosure conditions 

Always talk to your veterinarian before adjusting supplements or adding vitamin D3 to make sure it’s the right decision for your unique pet. 

Can reptiles recover from metabolic bone disease? 
Some reptiles can recover, especially when MBD is diagnosed early and treated promptly by an ​​exotic veterinarian. Some physical changes caused by MBD may be permanent.  

Can MBD be treated at home? 
Habitat and diet changes are important, but most reptiles with MBD require veterinary care. Always consult an exotic animal veterinarian for the best outcome.