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What Makes A Tortoise Shell Soft?

Last Updated on September 18, 2023 by Samantha Harris

Tortoises can develop soft shells due to a calcium deficiency or phosphorus surplus, causing Metabolic Bone Disease (MBD). It can also happen if they have a vitamin D3 deficiency or shell rot.

Young, growing tortoises have naturally soft shells, and certain species (like the pancake tortoise) are intended to have soft shells.

A healthy tortoise’s shell should be firm, smooth, and free of damage. It shouldn’t smell or produce discharge. Also, you should be able to see growth rings.

Why Does My Tortoise Have a Soft Shell?

There are five main causes of soft shells in tortoises. Each reason will present symptoms, enabling you to narrow down what’s wrong with your tortoise.

You need to note the signs to enable a veterinarian to diagnose and treat the condition. If you’re wondering, “What does it mean when a tortoise’s shell is soft?” it could be one of the following:

1/ Metabolic Bone Disease (MBD)

According to Companion Animal, metabolic bone disease (MBD) can cause soft shells. It’s a common condition in tortoises, but that doesn’t make it any less problematic. It occurs due to the following:

  • Calcium deficiency
  • A surplus of phosphorus

If your tortoise’s diet is short of calcium or has too much phosphorus, its body will burn calcium much faster. It won’t absorb it, weakening and fracturing over time.  

In addition to MBD, a calcium deficiency can lead to several other health problems. After all, calcium is essential to the healthy nervous system development.

Female tortoises about to breed or lay eggs need more calcium than others because they use their reserves to develop healthy eggs.


The common signs of metabolic bone disease are:

  • Soft or misshapen shells. While young tortoises and some species have naturally softer shells, misshapen shells aren’t normal.
  • Poor coordination and lack of movement. A tortoise with MBD won’t feel like moving around. If it does, it’ll have poorly coordinated movements.
  • Broken or fractured limbs. If the limbs break or fracture without reason, it signifies severe MDB. 
  • Female tortoises can’t lay eggs. If a female tortoise can’t lay eggs, it could die from this condition. If it lays the eggs, they may have soft or malformed shells due to a lack of calcium.

Other less common symptoms of MBD include:

  • Deformed jaws and limbs. The weakening of the skeleton is due to a lack of calcium.
  • Temporary or localized paralysis. This occurs when a calcium deficiency impedes the nervous system and prevents it from transmitting messages across the body.
  • Cloacae prolapse. A calcium deficiency impairs the nervous system and causes dietary issues.
bottom of tortoise shell soft


You can manage MBD with at-home treatments if your tortoise’s appetite is unaffected. Give your tortoise more calcium. You can add calcium-rich foods to its meals like the following:

  • Cuttlebones
  • Ground eggshells
  • Mulberry leaves
  • Collard greens

If necessary, dust small amounts of powdered calcium over your pet’s meals. Be careful not to use so much that your tortoise avoids eating the meal.


If you ensure your tortoise’s diet has enough calcium, your tortoise won’t develop MBD. So, provide calcium-rich milk thistle and dandelions.

Vitamin D3 Deficiency

Vitamin D3 is an essential nutrient because it helps a tortoise’s body utilize the calcium it gets from its diet. Most tortoises produce enough vitamin D3 from basking in the sun.

Unfortunately, some tortoises that don’t bask much develop a vitamin D3 deficiency, which prevents their bodies from using calcium, leading to soft shell.


The symptoms of a vitamin D3 deficiency are similar to MBD because they’re nutrient deficiency conditions, so the shell will soften and grow weak.  


Ensure your tortoise gets enough UV light while basking.

Check that the UVB lights in your tortoise’s enclosure are active and are wrapped in reflective material to maximize the effect on your tortoise.

You should also monitor the temperature of the areas where your tortoise basks are and ensure they’re well-adjusted for the tortoise species.

Sometimes, a tortoise’s D3 levels won’t balance after you improve its living conditions. If so, a vet may administer vitamin D3 injections to your tortoise.


Preventative measures center around ensuring your pet tortoise gets enough UV light.

That’s easily achieved with basking spots inside its enclosure that reach an adequate temperature. UV light and heat allow the body to metabolize and synthesize vitamin D3.

Shell Rot

Shell rot is a bacterial, fungal, or algal infection in tortoises.

Shell rot often occurs after a tortoise injures its shell, even if the damage is minor. The injury can allow bacteria and fungus to access the living tissue below the hard exterior.


You’ll notice the tortoise’s shell is soft underneath or see a wound. Symptoms include:

  • A noticeable and unpleasant odor from the site of the wound.
  • A foul discharge from the area.
  • Spreading softness through shell’s plates or scutes.
  • Pitting on the shell’s surface.
  • Scutes are falling off and exposing the dying tissue.


In its early stages, you can treat shell rot by removing any loose or soft tissue around the wound in the shell. Use these steps to treat soft shell:

  1. Give the wound a thorough clean using a povidone-iodine solution.
  2. Take a clean and soft toothbrush or nail brush to clean the wound site.
  3. Rinse the site with clean, warm water.
  4. Allow the area to air dry. If you cover the wound, use a fine gauze that allows oxygen to enter.


Here are some preventative measures to take to prevent shell rot in tortoises:

  • Clean the enclosure regularly, as a dirty living space invites bacteria and other pathogens.
  • Ensure the substrate humidity levels are optimal. Tortoises are more likely to develop shell and skin problems if the substrate inside their enclosure dries them out.
healthy tortoise shell vs unhealthy


If you’ve noticed that the bottom of your tortoise’s shell has gone soft, it could be because it’s young. A baby tortoise or juvenile with a soft shell is expected because shells strengthen as adults.

Monitor the shell’s development regularly to check if it’s getting harder.


If a baby tortoise has a soft shell due to its lack of physical advancement, it won’t display other symptoms that indicate a health problem. Tortoises less than 6-8 months old will have soft shells.

This is because young and baby tortoises grow rapidly, requiring the shell to expand with their bodies. It is much easier for the shell to expand when it is soft.


If your baby tortoise has a soft shell, it’ll harden after 6-8 months. Baby tortoises also get shell deformities and weaknesses from vitamin or mineral deficiencies.

Keep an eye on your tortoise as it grows. If your tortoise is healthy, its shell will grow at the same rate as its body – regardless of whether the shell is hard or soft. However, if your tortoise grows, its shell does not take it as a big warning sign.

Tortoise Species

Certain species of tortoise have softer shells than others.

If you’re unsure, find another tortoise of the same breed and compare the hardness and strength of the shell. If it’s similar and both tortoises are healthy, it’s not a concern.

The pancake tortoise has a soft shell because it lacks structure and segmentation. Instead, it has a flat, soft, and thin shell that allows it to flex easily. A pancake tortoise’s shell is also very light.

Since it can’t hide in its soft, flat shell, it quickly slides into gaps between rocks to escape predators.