Hypocalcemia in tortoises

Hypocalcemia refers to low levels of calcium (calcium deficiency) in the bloodstream. It is also referred to as 'metabolic bone disease' and 'soft shell syndrome'.

Calcium is one of the most important elements found inside the body. It has many jobs, but the most important one for understanding the effect on calcium in the body, is that it makes muscles contract. Calcium moves in and out of muscle cell walls causing the muscle fiber to contract. 
 

Calcium enters the body through food.  In the wild the tortoise would eat a huge variety of plants. In captivity, there is a danger to feed the tortoise only what he likes and selects. Variety is the key. Ensure you feed a wide range of foods to try and mimic the diet in the wild!

A common method of increasing the amount of calcium in the body is to dust the food with calcium powder. This will help provide your tortoise with the required calcium amounts.

Calcium cannot enter the body without vitamin D3. Vitamin D3 acts as a key in the intestine to let calcium into the blood stream. This is why UV light (wavelength 290-350 nm) is important.

UV light reacts with cholesterol in the skin and changes it through several chain reactions in the liver and finally in the kidney to make active vitamin D3 that the body is able to use. Reptiles cannot store Vitamin D3 and are unable to change vitamin D2 to D3 as mammals can. A good source of UV light at the correct height is vital (30-45 cm away from the tortoises main basking spot).

There are 2 hormones that control the levels of calcium in the blood stream. Calcium is potentially a dangerous element. Too much calcium in the body can lead to arterial sclerosis (hardening of the arteries) and too low calcium can lead to seizures (fits) and brittle bones.

Calcitonin is the hormone that pushes calcium into the bones if there is too much calcium in the blood stream. Bones act as a store for excess calcium.

Parathyroid hormone comes into action when there is too little calcium in the blood stream, depleting the bone store.

In tortoises this can cause muscular weakness. Most importantly it can cause weakening of the bones causing them to become spongy. This condition affects the whole skeleton, and the shell of the tortoise. Tortoises with low calcium levels are prone to severe damage from dog bites as the skeleton is not as strong as it should be.

There are several times in a tortoise’s life when calcium has an elevated role. Growth demands a lot of calcium to support lengthening bones. As the tortoise becomes an adult, the amount of calcium required is reduced.

Female tortoises also need extra calcium when they reach reproductive age. The ovaries and eggs require huge amounts of calcium. The body sacrifices the calcium in the bones to help calcify the eggs and to support growth.

To prevent this occurring you will need to ensure your tortoise's house is warm to help the digestion process of food, as well as ensuring your tortoise has a good quality UV bulb at the correct distance to maximize calcium absorption.

A good balanced diet with calcium and vitamin supplements is essential to make sure the muscles work correctly.

If your tortoise has low calcium he or she will need to go to the veterinarian for calcium treatments. This can sometimes mean your tortoise will have to stay in hospital whilst the calcium levels are stabilized.