Histopathology of ileal and liver tissues from steers in an experimental liver abscess challenge model

Authors: DORNBACH, COLTEN - Texas Tech University; HALES, KRISTIN - Texas Tech University; DAVIS, EMILY - Texas Tech University; Sanchez, Nicole; CRUZ PENN, MICHAEL - Texas Tech University; BALLOU, MICHAEL - Texas Tech University; GALYEAN, MICHAEL - Texas Tech University; MCDANIEL, ZACH - Texas Tech University; SMOCK, TAYLOR - Texas Tech University; NAGARAJA, T - Kansas State University; AMACHAWADI, RAGHAVENDRA - Kansas State University; LAWERENCE, TY - West Texas A & M University; Broadway, Paul

Submitted to: Frontiers in Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/22/2026
Publication Date: 5/11/2026
Citation: Dornbach, C.W., Hales, K.E., Davis, E.M., Sanchez, N.C., Cruz Penn, M., Ballou, M.A., Galyean, M.L., McDaniel, Z.S., Smock, T.M., Nagaraja, T.G., Amachawadi, R.G., Lawerence, T.E., Broadway, P.R. 2026. Histopathology of ileal and liver tissues from steers in an experimental liver abscess challenge model. Frontiers in Animal Science. 7:1814529. https://doi.org/10.3389/fanim.2026.1814529.
DOI: https://doi.org/10.3389/fanim.2026.1814529

Interpretive Summary: Liver abscesses cost producers almost $1 billion annually. The leading theory on liver abscess formation is that bacteria leave from damaged parts of the rumen wall and enter the bloodstream to reach the rumen. However, recent studies have suggested that multiple bacteria are involved in liver abscess formation, and that the lower gut may be an area where bacteria escape. Gross pathology limits scientists to view only macro structures within tissues. Yet, histology may provide valuable information on microstructures and subsequent effects on liver abscess formation. Scientists in Lubbock, Texas, along with university collaborators, evaluated the microstructure of the ileum and the liver in calves exposed to a liver abscess model. Data from this study found that changes in diet and dosing with bacteria found in liver abscesses increased inflammation and damage in the ileum. Results suggest that diet and bacteria exposure may work together to induce tissue damage and increase infection risk. These data will be of interest to physiologists and pathologists in the field of animal science.

Technical Abstract: Our objective was to identify the effects of diet and intraruminal inoculations of Fusobacterium necrophorum, Salmonella enterica, and Trueperella pyogenes on microstructures of ileal and liver tissues of Holstein steers experimentally challenged to induce liver abscesses (LA). Ileal epithelium and liver tissues were collected from Holstein steers (n = 80) across 2 separate experiments for histopathological analysis. Steers in Exp. 1 were assigned randomly to 1 of 3 treatments: 1) low-starch control diet primarily comprised of dry-rolled corn, alfalfa hay, and wet corn gluten feed (CON1; n = 13); 2) high-starch acidotic diet based on steam-flaked corn (AD1; n = 13); or 3) high-starch acidotic diet based on steam-flaked corn plus intraruminal inoculation with F. necrophorum subsp. necrophorum, S. enterica serotype Lubbock, and T. pyogenes (1 × 109 CFU/mL in 100 mL; ADB; n = 14). In Exp. 2, steers were assigned to 1 of 4 treatments: 1) low-starch control diet (CON2; n = 10); 2) high-starch acidotic diet based on steam-flaked corn (AD2; n = 10); 3) high-starch acidotic diet based on steam-flaked corn with intraruminal inoculation of F. necrophorum subsp. necrophorum (8.81 × 108 CFU/mL; ADF; n = 10); or 4) high-starch acidotic diet based on steam-flaked corn with intraruminal inoculation of F. necrophorum subsp. necrophorum (8.81 × 108 CFU/mL) and S. enterica subsp. Lubbock (1.52 × 109 CFU/mL; ADFS; n = 10). In Exp. 1 and 2, steers on high-starch acidotic diets (AD1, AD2) or inoculated with bacteria (ADB, ADF, and ADFS) had lesser ileal villi height and greater crypt depth compared to low-starch controls (CON1 and CON2; P < 0.01). Inflammatory cell counts were consistently elevated in acidotic and inoculated treatments, particularly ADFS (P = 0.05). Ileal villi height and crypt depth differed in steers with and without LA between experiments (P = 0.10). In Exp. 2, liver tissue damage was greatest for ADFS steers and least for CON2 steers (P = 0.03). Liver lymphocyte foci area was lesser (P = 0.02) and neutrophil score tended to be lesser (P = 0.08) in steers with a LA. When acidotic dietary cycles were coupled with bacterial inoculations containing Salmonella (i.e., ADB and ADFS), steers presented greater intestinal damage, immune cell infiltration, and liver pathology. Overall, these findings underscore that diet and pathogen exposure can synergistically modulate tissue damage and infection risk.