Osteopenia (Osteoporosis and Osteomalacia)
Osteopenia is a consequence of osteoporosis, a deficiency in the quantity of fully mineralized, structural bone. Cage layer fatigue (see Disorders of the Reproductive System: Hypocalcemia, Sudden Death, Osteoporosis, or Cage Layer Fatigue (Poultry)) describes a syndrome in which laying hens become paralyzed in their cages. The bones of the birds are osteopenic. The sternum is often deformed, and fractures cause infolding of the ribs at the junctions of the sternal and vertebral portions. Fractures can also occur in the long bones and vertebrae. The medullary bone is osteomalacic. The syndrome is due in part to a lack of exercise and high egg production, but severe problems are associated with inadequate calcium, phosphorus, or vitamin D. Calcium requirements during growth and before and during lay vary markedly. Sources of calcium that enable the slow release of mineral, such as oyster shell, appear to give the best results.
Outbreaks of tendon ruptures in broiler breeders are likely to be due to management practices or other diseases causing stress and/or joint and tendon trauma (eg, competition over feed space, heavy coccidiosis challenge, insufficient lighting, and high stocking densities). The increased tendon load with onset of egg production results in tendon failure, as the tendon has failed to develop adequately.
Last full review/revision March 2012 by Barry H. Thorp, BVMS, PhD, MRCVS