Hepatic Abscessation

• with supportive hepatitis
• especially common in cattle and sheep

Causes

• bacteria involved
  • Fusobacterium necrophorum 80% +
  • Arcanobacterium pyogenes
  • Streptococcus
  • Staphylococcus
  • Bacteroides
• spread from umbilicus in young animals
  • omphalophlebitis (navel ill)
  • usually mixed bacteria
    • Actinomyces pyogenes
    • Staphylococci (predominates)
• haematogenously from other pyaemic source
  • eg metritis or mastitis
  • bacteria invade ruminal wall and enter portal circulation to liver
• from rumenitis caused by overfeeding with grain
  • erosion of ruminal epithelium due to acidosis

Clinical Signs

• subclinical
• detected at exploratory laparotomy or sluaghter
• weight loss (most important)
• decreased weight gain or milk yields
• sporadic fever and anorexia

NB: animals can appear in good health as long as abscesses do not rupture

Gross

• large
• pale greenish-yellow pus
• thick fibrous capsule

Sequelae

• variable
  • resorption and healing
  • abscess may extend into the heaptic vein
    • give rise to thrombosis in the caudal vena cava
    • possible pulmonary abscesses
    • endocarditis
  • fibrous adhesion to adjacent viscera
    • if the abscess is near the surface
  • epistaxis, sudden death

NB: in many cases, abscesses are incidental findings at slaughter and result in condemnation of the affected livers