Vitamin D-dependent rickets is a disorder of bone development that leads to softening and weakening of the bones (rickets).
The disease is also known as Hereditary Vitamin D-Resistant Rickets (HVDRR).
Vitamin D enhances bone mineralization and calcium which are essential for hardening and strengthening the bones.
Affected dogs have defects in the vitamin D receptors in the target tissue which inhibit bone mineralization causing softening, weakening and bending of the bones and
skeletal malformations. Clinical signs include limb deformities, joint pain, lameness, limb deformities, spontaneous fractures, jaw deformities, and neurological signs. The disease can also cause alopecia. The causative mutation has been identified in Pomeranians. The condition is inherited as an autosomal recessive trait.
In affected dogs calcium levels are low (Hypocalcemia) which are necessary for the normal formation of bones and teeth. Affected dogs also have low levels of parathyroid hormone (PTH) which leads to secondary hyperparathyroidism.
Treatment: oral administration of active vitamin D and calcium supplements, however, bone deformities are irreversible.