Osteoporosis

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Osteoporosis (Atrophy)

  • Lesion, not a disease
  • Reduction in bone mass due to reduced osteoid (bone atrophy)
  • Bone resorption exceeds formation -> pathological loss of bone
  • Resorbed from:
    • Trabeculae, preserving the weight bearing ones until last
    • Endosteal surface of cortical bone
    • Along vascular channels
  • Longitudinal section
    • Fewer thin trabeculae
    • Enlarged medulla
    • Thin, porous cortex
  • Bone which remains is normally mineralised
  • Can be localised or generalised*Caused by:
    • Starvation - in farm animals due to protein and energy deficiency
    • Nutritional deficiency (calcium) and hypocalcaemia -> bone resorption
    • Senility
    • Physical inactivity (disuse) - muscular inactivity and reduced weight bearing, e.g. during limb casting
    • Glucocorticoids
    • Intestinal parasitism - in ruminants, malabsorption due to severe infestation
    • Copper deficiency - in lambs, calves, foals, pigs and dogs -> brittle bones
  • May be reversed in young growing animals