Osteomalacia

• Failure of mineralisation of osteoid / softening of the bones
• Active resorption of bone replaced by excess osteoid on trabeculae, endosteum of cortices and Haversian canals
• Decreased resistance to tension -> osteoid build-up at tendon insertions
• In advanced disease
  • Bones break easily and become deformed
  • Tendons may separate from bones
• Caused by prolonged phosphorus and Vitamin D deficiency
  • Vitamin D maintains normal plasma levels of calcium and phosphorus through acting on the intestines, bones and kidneys
• In mature animals
• Mainly grazing ruminants following gestation and lactation
  • Sunlight is important for production of vitamin D in the skin of ruminants
  • Vitamin d is also present in sun-dried hay
  • Mostly seen where there is long grass growing season with poor sunlight