Metabolic Bone Disease in the Indri
Metabolic bone disease (MBD) is a skeletal disorder affecting the indri (Indri indri), the largest living lemur, particularly when kept in captivity. It results from an imbalance in the body's management of calcium, phosphorus, and vitamin...
What is it?
Metabolic bone disease (MBD) is a skeletal disorder affecting the indri (Indri indri), the largest living lemur, particularly when kept in captivity. It results from an imbalance in the body's management of calcium, phosphorus, and vitamin D, which weakens the bones. This disease is well documented in many primates and exotic animals that are fed or housed inappropriately. The indri, a highly specialized foliage-eating species, is particularly vulnerable to this condition in captivity.
Key point
In young growing animals, this disease can have serious and irreversible consequences on the skeleton if not managed promptly.
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:
Early signs are often subtle: the animal moves less, appears stiff or hesitant to leap, an activity that is natural and essential for this tree-dwelling lemur.
Limping may develop, sometimes shifting from one limb to another.
As the disease progresses, bones become so fragile that they deform or fracture easily, even during routine movements.
Growing young animals may show delayed development, bowed limbs, or swelling around the joints and ribs.
The animal may lose appetite, appear fatigued, and display tremors in advanced cases, related to abnormally low blood calcium levels.
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 sustained dietary imbalance: insufficient calcium intake, excess phosphorus relative to calcium, or lack of active vitamin D.
In the indri, which is highly specialized for foliage-eating and difficult to feed authentically in captivity, a poorly formulated replacement diet is a major triggering factor.
Insufficient exposure to light capable of activating vitamin D synthesis in the skin also contributes to the disorder, as vitamin D is necessary for intestinal calcium absorption.
Captive indris are far more exposed to this disease than wild animals, because of the difficulty in replicating their highly specific natural diet.
Young animals undergoing bone growth are more vulnerable.
Lack of sunlight or appropriate lighting, a poorly varied diet, and absence of proper supplementation increase the risk.
Pregnant or nursing females, whose calcium needs are elevated, also form a group requiring monitoring.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian relies on the animal's feeding history, a complete clinical examination, and X-rays to assess bone density and structure.
Blood tests to measure calcium, phosphorus, and sometimes vitamin D levels provide additional information useful for diagnosis.
Treatment
Management is based on a gradual, supervised correction of the diet, with calcium and vitamin D supplementation tailored to the animal and decided and adjusted by a veterinarian.
Relative rest may be advised to limit the risk of fracture during the period of bone fragility.
In cases with fracture or significant deformation, specialized surgical or orthopedic care may be necessary.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Prevention is mainly based on feeding a diet as close as possible to the species' natural diet, rich and varied with appropriate vegetation, supplemented if needed with mineral and vitamin supplements monitored by a veterinarian specializing in exotic animals.
Access to suitable lighting, whether natural or artificial, that promotes vitamin D synthesis is recommended.
Regular follow-up examinations help detect nutritional imbalances early before clinical signs appear.
Possible complications
Without correction, the disease can progress to spontaneous fractures, permanent bone deformations, and major loss of mobility.
Neurological complications related to very low blood calcium levels can also occur in severe forms.
When to see a veterinarian
The animal appears stiff, limps, or avoids jumping when it normally would.
Deformation of a limb or joint swelling is visible.
The animal shows signs of pain, unusual fatigue, or refuses to eat.
Tremors or general weakness appear, particularly in a young growing animal.
Prognosis
The prognosis is favourable if the condition is detected early and the diet is corrected promptly, with good recovery of bone strength often occurring.
In advanced cases with multiple fractures or significant deformities, permanent complications may result and durably affect the animal's quality of life.
Frequently asked questions
Does metabolic bone disease affect lemurs in the wild?
It is very rare in the wild, where the indri has access to its varied natural diet and sufficient sunlight. The problem mainly concerns animals kept in captivity, whose diet is more difficult to balance.
Can an indri that is affected be completely healed?
Complete recovery is possible if the disease is detected at an early stage and the diet is corrected quickly under veterinary supervision. At advanced stages, deformities or lasting effects may persist.
How to know if an indri's diet is balanced in calcium?
Only a veterinarian specialized in exotic animals, possibly with the help of blood tests and a nutritional assessment, can precisely evaluate the calcium/phosphorus balance and vitamin D levels in the diet.
Is this disease linked to an infection?
No, this is not an infectious disease but a nutritional and metabolic disorder linked to a lasting mineral and vitamin imbalance.
References
AVMA — American Veterinary Medical Association
AAFP — American Association of Feline Practitioners
Content reviewed by the TunisieVet editorial team · Updated 02 September 2026
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