Metabolic Bone Disease in Giant Otters

What is it?

Metabolic bone disease is a disorder affecting bone strength that occurs primarily in giant otters living in captivity, particularly in young growing animals. It results from a sustained imbalance in calcium, phosphorus, and vitamin D provided through diet. This disease is not an infection; it is a problem with skeletal maintenance that develops gradually, often going unnoticed at first.

In this semi-aquatic, fish-eating species, the risk is particularly linked to the quality and variety of fish offered in captivity, as certain whole fish contain enzymes that destroy vitamin B1 and disrupt the animal's overall mineral balance.

Commonly observed signs

These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.

Causes and risk factors

The primary cause is prolonged dietary imbalance: insufficient calcium relative to phosphorus, lack of active vitamin D, or a diet consisting of a single fish species poor in essential minerals. A diet based solely on inadequately supplemented frozen whole fish is often responsible.

Lack of exposure to appropriate light can also play a role, as vitamin D synthesis in the skin depends on specific light wavelengths in many species.

Young otters in active growth phases face the highest risk, as their mineral requirements are elevated during this period.

A diet low in variety, consisting of a single fish species, increases risk, as does the absence of appropriate supplementation in captivity.

Insufficient light exposure, an enclosure poorly designed with limited natural light access, or chronic stress can worsen the condition.

Diagnosis and care

Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.

Treatment

Management is based first and foremost on gradual, supervised correction of the diet, with mineral and vitamin supplements prescribed by the veterinarian.

Relative rest and temporary environmental adjustments may be necessary to limit stress on a weakened skeleton. In some cases, pain relief treatment is added.

Prevention

Possible complications

Without correction, bone fragility may progress to spontaneous fractures, permanent deformities of the spine or limbs, and lasting loss of mobility.

In young animals, severe growth delay may compromise the animal's overall development.

When to see a veterinarian

Prognosis

The prognosis is favourable if the disease is detected early and the diet is corrected quickly; most young animals return to normal growth.

However, if bone deformities have already developed, some consequences may remain permanent despite correction of the diet.

Frequently asked questions

References

WOAH — Organisation mondiale de la santé animale (ex-OIE)

AAFP — American Association of Feline Practitioners

Content reviewed by the TunisieVet editorial team · Updated 04 September 2026