Mandrill Metabolic Bone Disease
Metabolic bone disease is a skeletal disorder linked to nutritional imbalance. It mainly affects young growing mandrills, but can also occur in adults. It is caused by a lack of calcium, an excess of phosphorus, or a lack of vitamin D in th...
What is it?
Metabolic bone disease is a skeletal disorder linked to nutritional imbalance. It mainly affects young growing mandrills, but can also occur in adults. It is caused by a lack of calcium, an excess of phosphorus, or a lack of vitamin D in the diet. This disease is well known in primates kept in captivity, particularly in zoos, when feeding or exposure to the sun is not properly managed.
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 bones become fragile and gradually deform. \nThe young mandrill may exhibit slowed growth, bowed limbs, or a stiff, painful gait. \nFractures can occur after minimal trauma, sometimes even during normal movements like jumping. \nThe animal may appear less active, avoid climbing, and show visible discomfort when moving. \nIn advanced cases, deformation of the rib cage can interfere with breathing.
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 an imbalance in the calcium/phosphorus ratio in the diet, often associated with a vitamin D deficiency. \nThis deficiency can result from a poorly formulated diet, low in calcium or too rich in phosphorus (excess of meat or certain fruits for example). \nA lack of exposure to natural light, necessary for vitamin D synthesis in the skin, often aggravates the problem in animals kept indoors.
Young, growing animals are most vulnerable because their calcium requirements are high. \nIndoor housing with little or no access to natural sunlight increases the risk. \nA diet not adapted to the species, poorly supplemented or unbalanced, is a determining factor. \nPregnant or lactating females also have increased calcium needs.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian uses dietary history, physical examination and x-rays to assess bone density and look for deformities or fractures. \nBlood tests measure calcium, phosphorus and sometimes vitamin D levels to confirm metabolic imbalance.
Treatment
Correcting the diet is the basis of treatment, with appropriate calcium and vitamin D supplementation under veterinary supervision. \nProgressive exposure to natural light or UV lighting can be implemented. \nIn severe cases with fractures, surgical or orthopedic treatment may be necessary. \nRest and limitation of physical activities are often recommended during bone consolidation.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
A balanced diet, formulated specifically for primates and respecting a good calcium/phosphorus ratio, is the best prevention. \nRegular access to natural light or suitable UV lighting promotes the synthesis of vitamin D. \nRegular nutritional monitoring by a veterinarian or an animal nutrition specialist makes it possible to detect deficiencies before symptoms appear.
Possible complications
Without correction, the disease can lead to multiple fractures, permanent skeletal deformities, and respiratory difficulty if the rib cage is affected. \nThe animal's mobility may be permanently compromised.
When to see a veterinarian
The animal limps or avoids climbing when it used to do so.
A deformity of the limbs or spine becomes visible.
A fracture occurs after a slight impact or without an apparent cause.
The young mandrill grows more slowly than its peers.
The animal shows signs of persistent pain or difficulty breathing.
Prognosis
The prognosis is favorable if the disease is detected early and the diet is corrected quickly. \nOn the other hand, bone deformities already established can remain permanent even after correction of the diet.
Frequently asked questions
Does this disease only affect young mandrills?
It is more common in growing young people, but adults can also be affected, particularly pregnant or lactating females whose calcium needs increase.
Can a mandrill fully recover?
If the disease is caught early, the bone can become solid again. But deformations already present may persist despite treatment.
Is the sun enough to prevent this disease?
Exposure to natural light helps produce vitamin D, but it does not replace a balanced, species-appropriate diet.
How do you know if a mandrill has a calcium imbalance?
Only a veterinarian can confirm this, through a clinical examination, x-rays and blood tests.
References
WOAH — Organisation mondiale de la santé animale (ex-OIE)
CDC — Centers for Disease Control and Prevention
Content reviewed by the TunisieVet editorial team · Updated 22 September 2026
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