Hepatotoxicity

  • sheep are very susceptible
    • they have poor ability to excrete copper in the bile
  • copper accumulates in hepatocytes until it reaches a critical level
    • the hepatocytes die and release the copper into the blood
    • causes haemolysis of the red blood cells
  • this haemolysis further damages the hepatocytes
    • releases even more copper

Predisposing factors

  • contamination of foodstuffs and pasture with copper
  • any damage to the biliary system as in ragwort poisoning
  • pastures low in molybdenum
    • increases the availability of dietary copper
    • molybdenum combines with copper to form insoluble complexes in the gut

Gross

  • carcass
    • jaundiced
    • reddish
  • liver
    • swollen
    • soft
    • orange in colour
  • kidneys
    • deep red
    • red urine due to haemoglobinuria

Microscopically

  • periacinar hepatic necrosis and profuse bile due to haemolysis and cholestasis
  • copper can be demonstrated with special stain - rhodanine

Genetic inheritance

  • Bedlington and West Highland White Terriers
  • copper toxicosis susceptibility
  • inherited as autosomal defect
  • copper levels can be very high in the livers of these animals
  • there is no haemolytic crisis
Clinical
  • ill thrift
  • progressive neurological signs due to liver failure
Gross
  • liver is small and fibrosed
  • jaundice is not a consistent feature