Treating Metabolic Bone Disease in Tortoises


There are plenty of things that can go wrong with the husbandry when you’re raising tortoises. But nothing strikes more fear in the hearts of tortoise keepers than metabolic bone disease. What makes it more terrifying is the fact that by the time any of the symptoms show up, it’s very difficult to reverse the effects. All that most people could do is make sure that the disease doesn’t get any worse. Sometimes, it’s simply too late for treatment altogether, and the animal will end up dying.

Treating metabolic bone disease tortoises get is hard, but it is doable. What is important is that you understand what metabolic bone disease is, what causes it, and fixing the husbandry issues related to your tortoises development. These include fixing the lack of calcium and vitamin D in their diet, reducing the amount of phosphorus they consume and adjusting your UVB Light-bulbs. Most importantly though we recommend seeking the aid of a qualified vet to help your tortoise get back to full health.

If you’re worried that your tortoise might have metabolic bone disease and you want to treat them, or you’re simply looking for ways to prevent it, then read on.

What Causes Metabolic Bone Disease?

Metabolic bone disease, or MBD, is the catch-all term for any disorder that ends up softening or deforming a tortoise’s shell or bones. Although it has many forms, the most common metabolic bone disease tortoises suffer from is caused by improper husbandry, improper diet, or a combination of both. Before we can start effectively treating MBD, we should look into what causes it.

Here are the most common causes of MBD amongst captive tortoises:

The Lack of Calcium in Their Diet

Much like people and other animals, tortoises need calcium in order for their bodies to function normally. Calcium helps with blood clotting, muscle contraction and, most importantly, for the heart muscles to beat. Tortoises get calcium from their diet, and any excess is stored in their bones and their shells.

So, more calcium basically means stronger bones. Tortoises, especially the larger species, tend to be very dense, and quite heavy. Strong leg bones are pretty much a requirement in order for them to move around properly.

Aside from their bones, tortoises also store calcium in their shells, which isn’t surprising since tortoise shells are basically their spine and ribcages that have fused together. If the tortoise isn’t getting enough calcium, then their bodies will try to take calcium wherever it can so it can function properly, and this includes taking it from the bones and the shell. Imagine having a spine or ribcage that can’t support your body, and you pretty much have an idea of how bad it can be for a tortoise.

Calcium is even more important for tortoises during reproduction. Tortoise eggshells are made from calcium, and if a female tortoise who’s carrying the eggs isn’t having enough calcium in their diet, then these eggs will not form properly. This will result in eggs that have leathery shells that are unable to support themselves, eventually collapsing under their own weight.

Females tortoises that don’t have enough calcium will also be unable to push the eggs out, since the muscles involved in such a function wouldn’t be able to contract properly. This means the eggs will end up being retained by the female, putting pressure on their organs, and may eventually lead to death unless given the proper treatment or surgery. This condition is known as egg binding, or dystocia.

The Lack of Vitamin D

Although calcium is the most important mineral when it comes to bone health, giving ample amounts of it on its own is not enough to prevent the type of metabolic bone disease tortoises can get. You’ll also need vitamin D. Now, the reason why vitamin D is so important is because it’s what allows your tortoise to absorb calcium. Without this vitamin, the calcium you feed your tortoise basically just passes through their digestive tract without being utilized.

Vitamin D is usually produced naturally when your tortoise is exposed to sunlight. Naturally, this is impossible to do if you’re living indoors, so you can either use lightbulbs that produce UVB, or you can feed tortoises vitamin D3, the consumable version of vitamin D, alongside calcium.

Too Much Phosphorus

Another thing you need to watch out for is the amount of phosphorus in your tortoise’s diet. Now, phosphorus in trace amounts isn’t a bad thing. In fact, it’s needed to keep the kidneys, blood vessels and muscles healthy. Unfortunately, if your tortoise is consuming more phosphorus than they do calcium, then they may end up having brittle bones, even though they’ve consumed ample amounts of calcium and vitamin D.

This is because phosphorus gets absorbed into our bones, much like calcium does, and if there’s more phosphorus in bones than calcium, then the bones end up becoming brittle. Too much phosphorus can also affect your tortoise’s ability to absorb other minerals, such as iron, magnesium and zinc. A good ratio to remember when picking out food for your tortoise, is 2:1, where there should only be one part phosphorus for every two parts of calcium.

Treating Metabolic Bone Disease

Now that you have an idea of what goes on when a tortoise suffers from MBD, let’s move on to how you can treat it. Bear in mind that if you believe your tortoise is showing signs of metabolic bone disease, the first thing you should do is to take them to the vet. They’re trained professionals, and they have the right knowledge that can help you and your tortoise out. However, as long as the tortoise is still eating normally, and there aren’t any really bad symptoms, you can treat your tortoise safely at home.

Also, since MBD is the type of disorder that takes a while for the first symptoms to show, it generally is too late to reverse its effects by the time you see any of them. “Treatment” mostly involves adjusting the husbandry, which means all you can really do at this point is prevent any further damage from happening.

Adjust Your UVB Lightbulbs

The first thing you’ll need to look at are the lightbulbs, especially the UVB bulbs. Make sure that the UVB bulb is situated around 10 – 12 inches above the substrate. Any lower, and you’ll be cooking your tortoise. Any higher means your tortoise isn’t getting any UVB. Also, make sure that your lightbulbs are new.

You’ll also need to check if the bulb is still producing UV. Although UVB bulbs can produce light for a really long time, they actually stop producing UVB anywhere between 6 -10 months after using them. That’s why it’s important to replace them at least twice a year. You can also find elongated florescent lamps, which can easily provide UVB for your entire enclosure, if you have a big one. We have a great article on what we think are the best UVB/heat lamps for your tortoise here. Best Heat Lamp For Tortoise.

Offer Them Calcium-rich Food

After checking on the UV lamps and fixing any issues there, the next thing you’ll need to look at is the diet. You’ll need to offer them food items that are rich in calcium. Calcium-rich foods include collard greens, mulberry leaves and cactus pads. You should also avoid greens that have too much phosphorus content. Remember the 2:1 calcium to phosphorus ratio.

Now, because tortoises are generally herbivores, barring some forest species that actually eat the occasional prey item like snails, worms and insects, meeting their calcium requirement through food alone might prove difficult. That’s why it’s important to add calcium supplements to their diets. Zoo Med’s Repti Calcium works wonders for this. You can also use Zoo Med’s Reptivite as a good alternative, since it does have calcium on top of all other vital nutrients.

Give Them Enough Vitamin D

Some tortoise species, especially hatchlings, are extremely shy. They would prefer to spend most of their time inside their hides. This makes it difficult to have them get exposed to UVB light, even if your lamps are working perfectly. This also means they won’t be producing any vitamin D for as long as they’re in hiding.

If giving them unfiltered sunlight is not an option, and you’re worried that they’re not getting enough UVB exposure from their lights, then you should at least supplement their food with vitamin D3 instead. Again, Zoo Med produces a variant of Repti Calcium with vitamin D3 in it, so your tortoise can still get their dose of vitamin D without being exposed to sunlight or UV lamps.

It’s difficult to overdose your tortoise with vitamin D. You will really need to force feed them vitamin D3 in order to get to levels that are considered lethal, but just to be safe, don’t give your tortoise vitamin D supplements more than 2 or 3 times a week.

For really bad cases of metabolic bone disease, you will need to take your tortoise to the vet in order for them to be injected directly with vitamin D3. You’ll also need to provide dietary support on top of going to the vet’s office for any follow-up treatment.

Final Thoughts

Metabolic bone disease is one of those diseases that can be very hard to bounce back from. But when treated properly, any tortoise can make a full recovery, although any deformities that show up in the shell or in the bones are sadly permanent. Most of the time, however, MBD is caused by bad husbandry, so everything that needs to be done to fix the issue can only be addressed by the keeper. So, if you know better, the remedy is always within reach.

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