Bones Metabolic - Pathology

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Hypovitaminosis A

Hypervitaminosis A

Hypervitaminosis A (Image sourced from Bristol Biomed Image Archive with permission)
  • Main lesions:
  • In cats fed bovine liver for prolonged periods
    • Rich in vitamin A in grazing animals
    • Vertebrae fuse with each other due to bone proliferation - cervical spondylosis (ankylosing exostosis of the vertebral column), especially in the neck
  • Can also be teratogenic, especially in pigs (cleft plate and abortions)


Hypervitaminosis D

  • May be of dietary or iatrogenic origin (has narrow safety margin)
  • Key features are hypercalcaemia with metastatic calcification of soft tissues
  • Acute poisoning
    • In dogs and cats often from rodenticides containing cholecalciferol
    • Grossly:
    • Microscopically:
      • Mucosal haemorrhage
      • Necrosis of crypts
      • Focal myocardial necrosis
      • Mineralisation of intestinal mucosa, blood vessel walls, lungs and kidneys
  • Chronic poisoning


Fluorine poisoning

  • F is widespread in nature
  • Pastures may be contaminated by industrial processes (e.g. brick manufacture)
  • Acute poisoning:
    • Gastroenteritis
    • Nephrosis
  • Chronic poisoning:
    • Dental abnormalities
      • Intoxication during teeth development
      • Foci of poor enamel formation - yellow, dark brown/black, chalky
      • Irregular wear of teeth, chip easily
    • Osteodystrophy = Fluorosis
      • Generalised skeletal disturbance
      • Most affected are metatarsals and mandibles
      • Periosteal hyperostosis + endosteal bone resorption -> thickened bones with enlarged marrow cavities


Lead poisoning

  • Lead can bind to mineral portion of bone and cartilage
  • In young animals ingesting large dose at once
    • -> Lead induced malfunction of osteoclasts
    • -> Transverse band of increased density on radiographs of metaphysis = "lead line" = growth retardation lattice