In the current investigation, qRT-PCR was used to measure the levels of antioxidant (CAT, GPX1, Keap1, OXSR1, ATOX1, GST, and Nrf2) and immune (IFN-γ, IL-4, TNF-α, MYD88, CCL5, TLR4, TLR9, LTF, and PRLR) genes in Barki ewes that were resistant and non-resistant to mastitis. The gene discussed is MYD88; the disease is mastitis.