{unfinished}}
Description
Hepatic abscessation occurs most commonly in cattle and is a common cause of economic losses due to carcass condemnation and reduced production efficiency. The disease is associated with a change from pasture to a high concentrate ration that predisposes to the development of rumenitis.
Pathogenesis
The main causative agent of the disease is Fusobacterium necrophorum, a gram-negative obligate anaerobe and a component of normal rumenal microflora. Arcanobacter pyogenes has also been implicated in the disease. Damage of the wall of the rumen secondary to rumenal acidosis leads to bacteraemia. Bacterial emboli from the inflamed rumen wall enter the hepatic portal system and are transmitted to the liver, leading to abscess formation.
Clinical Signs
Clinical signs are a rare feature of the disease and abscesses are frequently only observed as incidental findings at slaughter or post mortem. Detailed clinical examination may reveal signs of pyrexia, depression and weight loss. Evidence of abdominal pain may be present such as bruxism, grunting when pressure is applied to the xiphisternum and abduction of the elbows. There may be a history of feeding of a high-concentrate ration, anorexia and reduced milk production. Rupture of the abscesses is associated with anaphylactic shock and death.
References
- Divers, T. J., Peek, S. F. (2008) Rebhun's Diseases of Dairy Cattle Elsevier Health Sciences