Hamadryas metabolic bone disease
Hamadryas metabolic bone disease is a disorder that affects bone strength. It appears mainly in young growing animals in captivity, but can also affect weakened adults. It results from an imbalance between calcium, phosphorus and vitamin D...
What is it?
Hamadryas metabolic bone disease is a disorder that affects bone strength. It appears mainly in young growing animals in captivity, but can also affect weakened adults. It results from an imbalance between calcium, phosphorus and vitamin D in the body. This imbalance prevents bones from mineralizing properly. The bones then become softer, more fragile, sometimes deformed. This disease is not contagious: it is linked to the animal's diet and living conditions.
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 first signs are often discreet. The animal may seem less active than usual, less playful.
We frequently observe a lameness that changes legs depending on the day, a reluctance to climb or jump, and sometimes swelling in the joints or ribs.
In growing young people, growth and weight delay may appear. In advanced cases, deformities of the limbs or spine, or even fractures occurring without violent shock, may occur.
The pain often results in a hunched posture, reluctance to move, or unusual aggression if the animal is handled in a sensitive area.
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 nutritional imbalance: insufficient calcium intake, excess phosphorus, or vitamin D deficiency.
This vitamin is essential because it allows the body to absorb calcium from the intestine. In hamadryas, insufficient exposure to daylight (or suitable UV lighting in captivity) can aggravate vitamin D deficiency, as this species depends in part on it for its skin synthesis.
An poorly balanced diet, for example too rich in fruit and poor in mineral supplements, is a common cause in captivity.
Young, rapidly growing animals are most vulnerable because their calcium and vitamin D requirements are high.
Indoor housing without access to sufficient natural light or suitable UV lighting increases the risk.
An unbalanced diet, not supervised by a specialist in primate nutrition, is also a major risk factor.
Pregnant or lactating females have increased needs and may be more sensitive if their ration is not adjusted.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian carries out a complete clinical examination, observing the gait, posture and sensitivity of the limbs and spine.
X-rays make it possible to visualize bone density and detect possible deformities or fractures.
Blood tests measure the levels of calcium, phosphorus and sometimes vitamin D, in order to confirm the imbalance and guide treatment.
An assessment of the current food intake is an integral part of the diagnosis.
Treatment
Management is based on gradual correction of the diet, with appropriate calcium and vitamin D supplements, under strict veterinary supervision.
Exposure to an appropriate UV light source can be implemented.
In severe cases with fractures or significant deformities, orthopedic or surgical treatment may be necessary.
Relative rest and adjustment of the environment (limiting jumps, adapted surfaces) are often recommended during the recovery phase.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Prevention is based above all on a balanced diet, formulated specifically for primates, with an appropriate calcium/phosphorus ratio.
Regular access to natural light, or failing that veterinary-grade UV lighting, helps with the synthesis of vitamin D.
Regular veterinary checks allow any signs of imbalance to be identified early, before the appearance of bone complications.
Monitoring growth in young people is particularly recommended.
Possible complications
Without correction, the disease can progress to spontaneous fractures, permanent deformities of the limbs or spine, and lasting disability.
In young animals, marked growth retardation may persist into adulthood.
Neurological complications are possible if the spine is deformed to the point of compressing the spinal cord.
When to see a veterinarian
The animal limps or avoids moving normally.
He refuses to jump, climb or get up like usual.
Swelling appears on a joint, rib or limb.
A young animal seems to be stunted in growth compared to its peers.
A fracture or deformity appears without obvious trauma.
Prognosis
The prognosis is favorable if the disease is detected early and the diet is corrected quickly: the bones can regain strength, especially in young animals still growing.
On the other hand, if significant bone deformities or multiple fractures have already occurred, certain after-effects may remain permanent despite treatment.
Long-term veterinary follow-up remains recommended to monitor progress.
Frequently asked questions
Is this disease contagious to other hamadryas?
No, it is not contagious. It is linked to the animal's diet and environment, not to a transmissible infectious agent.
Can an adult hamadryas also be affected?
Yes, even if growing young people are most at risk, an adult with an unbalanced diet or little exposure to light can also develop this disease.
Can we give calcium without veterinary advice?
No, an excess or a poorly dosed imbalance can worsen the situation. Any supplementation must be supervised by a veterinarian specializing in primates.
Are bone deformities always reversible?
Not always. Early treatment greatly increases the chances of recovery, but deformities that have been present for a long time can leave after-effects.
References
WSAVA — World Small Animal Veterinary Association
Content reviewed by the TunisieVet editorial team · Updated 23 September 2026
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