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While lizards and turtles are some of the most popular small pets and are generally considered fairly low-maintenance, they must be fed specific diets and housed under specific environmental conditions to stay healthy.  Without the right knowledge and species-specific solutions—such as bearded dragon supplies—it’s easy for these pets to develop serious illnesses, including metabolic bone disease.

What is metabolic bone disease? 

Metabolic bone disease (MBD)—or nutritional secondary hyperparathyroidism—is a syndrome common in pet lizards and turtles, especially those young and growing, whose nutritional and environmental needs are not met. Some of the symptoms seen with this syndrome include the following:

  • Swollen limbs and jaw—referred to as fibrous osteodystrophy, in which bones break down and are replaced by fibrous connective tissue. Soft, rubbery bones—referred to as osteomalacia, in which bones lack mineral components, such as calcium
  • Brittle, easily fractured bones—referred to as osteoporosis, in which bones not only lack calcium and other minerals, but also other structural components

With metabolic bone disease, a reptile’s bones become weak. This includes the bones of the upper and lower shell of turtles and tortoises—called the carapace and plastron, respectively. The bones and shell typically become deformed and may break more easily. MBD occurs most commonly in lizards, turtles and tortoises, but it can also affect snakes.

While MBD in reptiles is common, it is also serious. When unrecognized and untreated, MBD can cause weakness, tremors, fractures and severe movement restrictions that can affect a pet’s ability to eat, bask and even survive. Consult your veterinarian immediately if you suspect your reptile has MBD.

Causes of metabolic bone disease

MBD results from an imbalance of calcium and phosphorus in the body from either a lack of dietary calcium or inadequate exposure to ultraviolet (UV) light. Calcium and phosphorus are essential to building and maintaining a strong skeleton. Bones are living tissue—the minerals they contain are constantly being broken down, resorbed back into the body and replaced with minerals absorbed through the reptile’s diet.  

To complete the cycle of bone metabolism and repair, their body depends on two types of cells—osteoblasts and osteoclasts. The process also requires various hormones, vitamins and minerals, including calcium and phosphorus. Without the right balance of these elements—along with the proper environmental conditions—metabolic bone disease can occur. 

 Many cases of MBD in reptiles can be traced back to a lack of dietary calcium. However, reptiles also require adequate exposure to UV light to synthesize vitamin D in their skin so that they can utilize dietary calcium for bone formation. When a reptile doesn’t get enough calcium or have sufficient UV light exposure, phosphorus levels in the body increase and their bones will break down to provide the calcium essential to numerous metabolic processes. This breakdown canresult in bones becoming weak and soft or brittle and easily fractured 

Generally, lizards and turtles should have a two-to-one ratio of calcium to phosphorus in their bodies. There are a few different ways this ratio can become unbalanced: 

  • Excess dietary phosphorus 
  • Insufficient dietary calcium 
  • Impaired body synthesis of vitamin D3 
  • Inadequate UVB light exposure
  • Thyroid, intestinal or kidney disease that affects calcium metabolism

How do you know what factors are contributing to metabolic bone disease in your reptile? A visit to your veterinarian will help you determine the cause and provide solutions to treat the problem.

Signs of MBD 

Calcium deficiency symptoms in bearded dragons and other reptiles aren’t always easy to spot—especially in the early stages. Your pet simply may be lethargic or have a reduced appetite, but these generalized signs can occur with many other disorders. However, without treatment, metabolic bone disease typically progresses and will produce more obvious symptoms, such as a leopard gecko shaking while walking.  

 Some of the symptoms of metabolic bone disease in reptiles include:

  • Swollen or bowed legs 
  • Rubbery jaw affecting their ability to eat 
  • A soft shell in turtles and tortoises 
  • Arched or curved spine and tail
  • Weakness and reluctance to move 
  • Tooth decalcification/teeth falling out 
  • Strange gait 
  • Tremors and twitches 
  • Inability to climb 
  • Constipation
  • Frequent bone fractures 
  • Seizures and paralysis 

As with any disorder, the outcome of metabolic bone disease is more favorable if it’s caught early. If you see any of the above symptoms, take your pet reptile to your veterinarian. MBD can be confused with other disorders—such as kidney problems or infections—so an official diagnosis by a trained veterinarian is necessary. Your veterinarian will likely take X-rays to help them see skeletal demineralization and abnormal bone structure. They also will likely take blood samples to measure blood calcium and phosphorus levels to diagnose MBD.

How can I prevent metabolic bone disease?

Providing the right nutrition, heating and lighting is the best way to prevent metabolic bone disease in reptiles. Be sure you’ve done your research to find the proper leopard gecko supplies or solutions for other pets. Not all reptiles have the same nutritional needs or require the same environmental conditions. Learn about the unique requirements of your reptile so that you can keep them happy and healthy.  Specific factors to consider when caring for a pet reptile include:

Nutrition To provide a balanced diet that can help prevent MBD in reptiles, it’s important to understand what they eat and what their food eats. For example, insectivorous lizards in nature typically have a more varied and nutritionally balanced diet than pet lizards, eating a wide variety of berries, leaves, live worms, eggs and insects—including beetles, spiders, moths, flies and ants. These insects also have a more varied diet, making them more nutritious, and that nutrition is passed on to the lizards when they eat them.

Most pet reptiles are primarily fed mealworms and crickets. Live crickets typically contain little calcium, and a diet consisting solely of crickets will not meet your pet’s calcium requirement. You must supplement with additional vitamins and minerals to ensure that your reptile gets the complete nutrition they need.

Lighting and heating  As cold-blooded pets that cannot regulate their internal body temperature, reptiles are dependent on external sources of heat to ensure their bodies function properly. They also require UV light to make vitamin D in their skin so that they can absorb dietary calcium, which is essential for preventing metabolic bone disease.  

 Reptiles in nature are exposed to both UVA and UVB light from the sun. However, because these light wavelengths can’t penetrate glass, pet reptiles often don’t get enough UV exposure and are prone to developing metabolic bone disease as a result. To prevent this, you will need to place special UV bulbs in specific locations of their habitat and make sure they are kept on for the proper amount of time each day.  

 While nocturnal reptiles—including leopard geckos, ball pythons and boa constrictors— get enough vitamin D3 through their diet and don’t rely on UVB light to manufacture it in their bodies, they are still healthier as pets when provided low-level UV light. On the other hand, diurnal reptiles—like bearded dragons, chameleons and most tortoises—must be exposed to UVB light to make vitamin D3 in their skin so they can absorb dietary calcium. Check out our guide D3 in Reptile Health: What You Should Know for more information on this supplement. 

How is metabolic bone disease treated? 

The first step in treating metabolic bone disease is to correct your pet’s diet and environmental conditions. Educate yourself about the general husbandry and nutrition guidelines for your pet’s particular species so that you can optimize their habitat and diet. Your veterinarian can also perform blood tests to determine the ratio of calcium to phosphorus in their blood. In general, their blood calcium level should be two times their blood phosphorus level. Having deficient calcium or excessive phosphorus can cause MBD in reptiles.  Your veterinarian can recommend specific dietary supplements to help treat metabolic bone disease if calcium and phosphorus are imbalanced in your pet reptile.

If MBD has progressed, your pet may need fluid therapy or medications such as calcium gluconate or calcitriol. A hormone injection called calcitonin salmon may be used in some cases to help your pet absorb calcium and speed up the healing process. Your vet may also recommend changes in your pet’s habitat conditions, including UV lighting. If your pet has broken bones, they may need surgery or splinting to repair the fracture, as well as pain medication to feel more comfortable.  

 Without treatment, reptiles with MBD generally will not survive. However, with timely treatment and husbandry adjustments, the prognosis may be good—depending on the stage of MBD at which your pet is diagnosed and the presence of any other underlying health issues. Reptiles with advanced MBD may not eat on their own and require syringe feeding and intensive care until they recover. Even after recovery, MBD in reptiles can resurface if the proper diet and husbandry are not maintained—you must remain vigilant in providing the appropriate nutrition and environment for your pet.  

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