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