Blood cell counts and chemistry in steers with experimentally induced liver abscesses with or without ruminal acidosis

The study evaluated changes in blood cell counts, plasma and serum chemistry, including hepatic enzymes, in steers with liver abscesses (LA) induced experimentally by intraportal (IP) or intraruminal (IR) inoculation of Fusobacterium necrophorum subsp. necrophorum. Forty steers (20 Holsteins and 20 dairy-derived beef; BW = 206 ± 45 kg) were assigned using a randomized complete block design to 1 of 4 treatments. Treatment groups included a negative control (CON), a group with induced ruminal acidosis (RA), a group with induced ruminal acidosis followed by intraruminal bacterial inoculation (IR), and a group with intraportal bacterial inoculation, without RA induction (IP). Study duration was 48 d. All steers were initially fed a low-starch diet. On d 4, steers in the RA and IR groups were restricted to 80% of the previous DMI, then on d 5 and 6, were offered a high-starch diet at 120% (d 5) and 110% (d 6) of previous DMI. This challenge cycle was repeated beginning on d 10. Steers in the IR group were inoculated with F. necrophorum on d 19 and 26, and the IP group was inoculated with F. necrophorum on d 26 through the hepatic portal vein via ultrasound-guided percutaneous catheterization. Blood samples were collected on d 26, 33, 40, and 47. Steers were euthanized and necropsied on d 48, and livers were examined for LA presence and severity. Seven of 10 steers in the IP group developed LA, as did 5 of 10 in the IR group. Steers in CON and RA groups demonstrated no changes in blood over time. Steers with LA in the IR group had leukocytosis and neutrophilia (P < 0.01) compared to CON or RA group. Steers with LA in the IP group had greater (P < 0.01) total leukocytes, neutrophils, and platelet counts, greater (P < 0.01) plasma total protein and fibrinogen concentrations, greater (P < 0.01) serum globulin concentrations, and reduced (P < 0.01) albumin: globulin ratios compared to the IR steers. Gamma-glutamyl transferase activity was elevated (P < 0.01) in the IP group compared to CON, RA, and IR groups. Steers with severe abscesses with adhesions had more pronounced blood changes than steers with severe abscesses with no adhesions. The difference in blood changes with LA induced by IP or IR was likely because 7 steers in the IP group had severe abscesses with adhesions compared to 1 of 5 steers in the IR group. Overall, blood changes reflected active inflammation and liver injury associated with LA and the magnitude of changes depended on abscess severity.