Osteomalacia has a pathogenesis similar to that of rickets but
it is seen in mature bones. Because bones mature at different
rates, both rickets and osteomalacia can be seen in the same
animal. Osteomalacia is characterized by an accumulation of
excessive unmineralized osteoid on trabecular surfaces. Affected
animals are unthrifty and may exhibit pica. Nonspecific shifting
lamenesses are common. Fractures can be seen, especially in the
ribs, pelvis, and long bones. Spinal deformation such as
lordosis or kyphosis may be seen. In horses, nutritional
osteodystrophy is known as bran disease, miller's disease, and
“big head.” The diet of pampered horses is often too high in
grains and low in forage; such a diet is high in phosphorus and
low in calcium. Many of the obscure lamenesses of horses have
been attributed to nutritional osteodystrophy. The pathologic
changes are similar to those in other species, with the provisos
that the bones of the head are particularly affected in severe
cases and that gross or micros