Innate immunity measurements in healthy and footrot-affected sheep treated with selenium or saline. Footrot-affected (FR) sheep, regardless of Se treatment, had A) smaller ear wheal diameters compared with healthy sheep 30 min after KLH challenge (P = 0.05), whereas Se treatment decreased the 30 min response to histamine (P = 0.02). B) After stratifying FR-affected sheep by whole-blood Se (WB-Se) status at the time of the DTH assay (WB-Se cut-off: 250 ng/mL), sheep with WB-Se concentrations above 250 ng/mL (FR-High Se) had a decreased response to histamine at 30 min (P = 0.02). C) FR-affected sheep had a lower percent neutrophil bacterial killing of Lactococcus lactis compared with healthy sheep (P = 0.04), which was not altered by Se treatment (P = 0.36), or D) Se status (P = 0.26). E) FR-affected sheep had lower mRNA concentrations of IL-8R compared with healthy sheep (P = 0.02), which were not altered by Se treatment (P = 0.24), or F) Se status (P = 0.32). FR-High Se status sheep tended to have increased mRNA concentrations of L-selectin (P = 0.07).