Abscesses in the liver of cattle are focal infections resulting from entry and establishment of pyogenic bacteria. There are several routes by which bacteria reach the liver, but entry via portal blood is by far the most frequent, because it drains the gastrointestinal tract, a source of bacteria. Liver abscesses can occur at all ages and in all types of cattle, but are most common in feedlot cattle fed high-grain finishing diets. The generally accepted pathogenesis of liver abscess includes chronic ruminal acidosis that leads to rumenitis, which then allows bacteria, primarily Fusobacterium necrophorum, to cross the epithelial barrier to enter the portal circulation. Bacteria from the portal circulation are filtered by the liver, leading to growth, production of virulence factors, particularly leukotoxin, damage to hepatic parenchyma, and abscess formation. Trueperella (formerly Arcanobacterium) pyogenes is the second most common bacterial species isolated from liver abscesses. Another bacterial species that has been recently isolated from liver abscesses is Salmonella enterica. Liver abscesses in cattle are of significant economic concern to the feedlot industry because of liver condemnation, reduction in performance and carcass yield. Liver abscess data collected from several packing plants have indicated a higher incidence of liver abscesses, particularly of the A+ score (most severe), in Holstein steers than the traditional beef cattle. Holstein steers raised for beef production are different from traditional beef breeds. Among the differences include more digestive and metabolic disorders and death losses in Holstein steers compared with beef breeds. The generally accepted reason for the increased digestive disorders, liver abscesses and death loss is the greater number of days Holsteins are on feed. However, it is not known whether the bacterial flora of liver abscesses of Holstein steers is in any way different from abscesses of the traditional beef cattle. In a recent study, liver abscesses in Holstein steers had a more diverse bacterial flora compared with traditional beef cattle. However, the prevalence of the major bacterial species, F. necrophorum, and T. pyogenes were similar between the 2 cattle types.