- 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