First description of LPS-treated, pen-housed feeder cattle as a model of bacterial infection

Authors: Chitko-Mckown, Carol; McDaneld, Tara; Kuehn, Larry; Lindholm-Perry, Amanda; Clawson, Michael - Mike; Wynn, Emily

Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 10/4/2022
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Intravenous administration of 0.25µg/kg BW LPS in saline to catheterized cattle mimics infection with Gram negative bacteria as indicated by fever, malaise, and elevated haptoglobin. However, catheterization requires individual housing which does not mirror a feedlot environment. We report the results of a trial using this concentration of LPS to treat cattle without catheterization and housing them in a pen setting along with control/sham-treated animals as a prototype for collecting responses to LPS-treatment in a feed yard setting. Thirty fall-born calves were used to mirror typical feedlot pen numbers. Animals were weighed, body temperature measured, and a blood sample obtained prior to administration of LPS. Fifteen feedlot steers were treated with LPS (0.25µg/kg; in 1-3ml of saline administered IV) and 15 feedlot steers served as controls and were treated with saline. After treatment, cattle were maintained on trial for four weeks. Blood samples were collected with a syringe via jugular venipuncture on Day 0 prior to treatment, then on Days 1, 7, 14, 21, and 28, after treatment. Response variable were modeled with fixed effects of pen and treatment using SAS. LPS-treated steers showed signs of malaise and had stopped eating within 2h. By 4h post-treatment, the animals had returned to normal behavior. On D1, haptoglobin levels were significantly higher (P=0.00159) in LPS-treated steers than in the controls. Neutrophil numbers were significantly higer (P=0.0007) in LPS-treated cattle on D1, however percent lymphocytes were significantly lower in those animals (P=0.0001). No animals required any post-treatment veterinary intervention and rectal temperatures and weights were similar between both treatment groups for the next 28 days. Our results show that LPS can be used to mimic a bacterial infection similar to that observed in calves suffering from BRDC. Because catheterization was not required, and no veterinary intervention was needed, this technique can be used in animals enrolled in studies where housing in typical feed yard pens is required.