Metabolic Bone Disease

Metabolic Bone Disease (MBD) is the most common nutritional problem that occurs in reptiles. This is a disease caused by a lack of calcium or an increase of phosphorus in reptiles.

Calcium is a very important mineral in nerve function and also in metabolic processes. A calcium deficiency can cause weakened muscle contraction (especially in their heart) and a decreased ability for their blood to clot. In extreme cases MBD can lead to cardiac failure.

Too much phosphorus can also lead to a loss of calcium. The calcium loss is because phosphorus causes an increased production of calcium phosphate in their gut. Calcium phosphate is an insoluble salt, and a buildup in their gut can cause a calcium deficiency in your reptile. 

The bodies of reptiles have calcium to a phosphorus ratio that they need to maintain to keep from getting MBD. This range is usually from 1.5:1 to 2:1. 2:1 calcium to phosphorus is best. If the calcium to phosphate ratio falls below 2:1, it causes phosphate ion absorption in their body that can lead to hypophosphatemia. This stimulates the secretion of the parathyroid hormone through the parathyroid glands. The parathyroid hormone signals the body to take calcium from anywhere it can find it. The most abundant supply of calcium in the body is stored in the reptile’s bones. As calcium is taken from bones, they become very soft and weak.

If this is not treated, the body tries to strengthen the bones. Without a supply of calcium to replace what was taken it attempts to use fibro collagenous connective tissue. This can cause visible bumps on the bone, mainly in the vertebrae along the back and the base of the tail. The longer this continues before it is treated, the more likely permanent and irreversible damage will occur.

What Can Cause Calcium to Phosphorus Ratio Change

There are few reasons which can lead to a change in the calcium to phosphorus ratio;

Wrong Diet

One of the main reasons is a bad diet. Too much phosphorus or lack of calcium or both can cause the ratio to fall out of balance. Too much fat can reduce the absorption of calcium or substances that help calcium absorption.

Many reptile owners report that their reptile loves oatmeal. The problem with oatmeal is it contains a lot of phosphorus compared to calcium. The ratio is only 1.3:1. The problem is when you start with a lot of phosphorus you need a lot more calcium to keep the ratio up. Many reptile owners don’t think it’s worth the trouble for foods like oatmeal.

Vitamin D Deficiency

Lack of vitamin D can cause poor calcium absorption. Reptiles mostly get vitamin D from sunlight rather than food. This is why they need regular exposure to both UVA and UVB light. Improper or insufficient lighting leading to a vitamin D deficiency can cause MBD.

Temperature Changes

Temperature decreases can lead to changes in the calcium to phosphorus ratio. Cold temperatures can slow down the rate of digestion occurring, slower digestion could lead to less calcium absorption.

The Side Effect of Diseases

Some diseases, like kidney and liver disease can also cause changes in the calcium to phosphorus ratio. But these types of cases are very rare.

Symptoms of MBD

Just like any other disease, symptoms of MBD differ from reptile to reptile, but they still have some common symptoms, these are:

  • Soft and weak bones
  • Lethargy and reluctance to move
  • Paralysis
  • Weight loss
  • Muscle fasciculation
  • Seizures

Diagnosis of MBD

The early-stage symptoms such as swollen jaws and leg bumps, weakened carapace (in turtles), and plastron in turtles and tortoises. An X-ray and blood check by your vet are the only real way to be sure if your reptile has MBD.

X-rays of reptiles with MBD will show abnormally large and misshapen bones. It also shows expansions in the cortical bone surrounding the medullary cavities which appear normal.

Calcium and phosphorus concentrations along with their ratios can be figured out from blood tests. Hypocalcemic adults should have normal ranges unless blood is drawn immediately after a twitching episode. Juvenile reptiles also tend to show concentrations in the normal range even if they have MBD.  Blood tests should only be used as guidelines to confirm the X-ray result and not as an exact result on its own.

Treatment for MBD

The main cause for Metabolic Bone Disease is a lack of calcium in the body, the main treatment is going to be supplying calcium to the reptile.

The reptiles should be given a properly balanced diet with nutrient-dense fresh fruits and vegetables as well as protein like crickets and mealworms. Calcium supplements should also be used regularly. These can be found in powder form and then dusted onto food they eat. It’s very easy to dump a few crickets into some calcium powder right before feeding them to your reptile.

Maintaining the temperature of their housing is also very important. Your reptile’s housing should have warm basking areas and cooler shaded areas along with day and night temperature gradients to allow them to regulate their body temperature.

Exposure to UVA and UVB are vital as well as day and night light cycles. The time of these light cycles varies with species, but they should be based on the native environment of the species.

Treatments should be given every 6-12 hours until the symptoms visibly reduce.

In severe cases, an extreme supply of calcium and vitamin D should be given to help the reptile rebuild its bones. Vitamin D helps your reptile absorb calcium better. They normally get vitamin D from UVA/UVB lights, which is why these lights are so important.

Prevention of MBD

The only way to prevent a reptile from getting MBD is to make sure they have enough calcium in their body. To make sure that they have enough calcium, your reptile should be given a proper diet, enough exposure to UV light, and have good housing.

It’s vital to keep the calcium to phosphorus in balance as close as possible to a 2:1 ratio. To get this ratio, your reptile should be fed a balanced diet with less fat. As I mentioned before, too much fat can reduce calcium absorption.

Supplying your pet with enough vitamin D is also very important. By allowing your reptile to have contact with more UVA and UVB light, vitamin D deficiency could be reduced.

Maintaining the temperature of your reptile’s habitat is also important because cold environments reduce digestion causing less calcium absorption. 

Related Questions

Can Metabolic Bone Disease in reptiles be Reversed?

If the disease is detected at an early stage, the disease could be reversed with proper care and treatment. These often include treatment and prevention methods for MBD mentioned above.

Is Metabolic Bone Disease Painful?

Metabolic Bone Disease can cause bone pains and bone fractures along with loss of height due to a lack of calcium in the body.

What is the Most Common Metabolic Bone Disease?

Osteoporosis is by far the most common bone disease found among MBD patients.