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Softening of the shell
Softening of the shell is a common bone disorder in captive-bred Greek tortoises (Testudo graeca). The shell, normally hard and rigid, becomes soft, deformed or spongy to the touch. It is not an infectious disease but the result of a prolon...
What is it?
Softening of the shell is a common bone disorder in captive-bred Greek tortoises (Testudo graeca). The shell, normally hard and rigid, becomes soft, deformed or spongy to the touch. It is not an infectious disease but the result of a prolonged nutritional and environmental imbalance, called metabolic bone disease. It mainly affects young growing turtles but can also affect adults who are poorly nourished or poorly exposed to the sun.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
The carapace loses its normal hardness, particularly on the plastron (ventral part) and the edges of the scales. It may feel springy, bumpy, or have sunken areas.
Deformities of the spine or limbs may appear over time.
The turtle often becomes less active, eats less, and may have difficulty moving or lifting its body.
In advanced cases, fractures or difficulty breathing may occur as the deformed shell compresses the internal organs.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
The main cause is a chronic lack of calcium in the diet, often associated with excess phosphorus (unsuitable foods such as fruit, lettuce, or dog/cat food). A deficiency in vitamin D3, essential for absorbing calcium, aggravates the problem. This vitamin is normally produced by the turtle's skin using ultraviolet B (UVB) rays from the sun or a specific lamp. Without sufficient UVB exposure, even a correct calcium diet is not enough.
Turtles kept indoors without suitable UVB lamps are particularly at risk. A diet too rich in fruits, vegetables low in calcium (lettuce, tomatoes) or industrial foods for other animals promotes the disorder. Young, growing turtles have higher calcium requirements and are therefore more vulnerable. A lack of exposure to natural sunlight, common among turtles kept in terrariums all year round, is a major aggravating factor.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian examines the shell by palpation to assess its hardness and look for deformations. X-rays are used to measure bone density and detect fractures or internal abnormalities. A blood test can be taken to measure blood calcium and phosphorus. The dietary history and rearing conditions (exposure to the sun, type of terrarium) are systematically discussed.
Treatment
Treatment is based on correcting the diet with appropriate calcium and vitamin D3 supplementation, under veterinary supervision. UVB exposure should be immediately implemented or improved. In severe cases, supportive care may be necessary (rehydration, pain management). Healing is gradual and often requires several months of follow-up.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Offer a varied diet based on wild plants and vegetables rich in calcium (dandelion, clover, mulberry leaves), avoiding sugary fruits and dog or cat food.
Ensure regular and sufficient exposure to natural sunlight, without glass or plastic which block UVB, or install a specific UVB lamp for indoor reptiles.
Calcium supplementation may be recommended by the veterinarian, especially for young growing turtles.
Regular veterinary checks allow any signs of imbalance to be detected early.
Possible complications
Left untreated, the disease can lead to permanent shell and skeletal deformities, spontaneous fractures, compression of the lungs or other internal organs, and increased mortality especially in young turtles.
When to see a veterinarian
The shell feels soft, supple, or bumpy to the touch.
The turtle has difficulty moving or lifting its body.
Visible deformations appear on the carapace or limbs.
The turtle has been eating less or seems depressed for several days.
Prognosis
The prognosis is favorable if the problem is detected early and diet and UVB exposure are corrected quickly. In young turtles, a clear improvement in the strength of the shell can be observed after several months of appropriate care. On the other hand, already established deformities often remain permanent even after healing of the underlying metabolic disorder.
Frequently asked questions
Is shell softening contagious?
No, it is not an infectious disease. It results from a nutritional imbalance and a lack of UVB light, so it is not transmitted between turtles.
Can a soft shell become hard again?
Yes, if the cause is corrected early (diet, UVB exposure), the shell can gradually regain hardness over several months. Deformations already present often remain permanent.
Can adult turtles also be affected?
Yes, although growing young are most at risk, an adult turtle that is poorly nourished or has little exposure to sunlight can develop this disorder.
Is a UVB lamp really essential?
Yes for a turtle living indoors. Without UVB, the skin cannot produce the vitamin D3 necessary for calcium absorption, even if the diet is correct.
References
AVMA — American Veterinary Medical Association
WSAVA — World Small Animal Veterinary Association
Content reviewed by the TunisieVet editorial team · Updated 11 August 2026
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