The greatest potential levels of mRNA were found for the mastitis-affected dairy cows’ NFkB (2.63 ± 0.11) and COX18 (2.64 ± 0.16) genes, respectively, while CHL1 (0.44 ± 0.12 and 0.64 ± 0.11) had the lowest levels in both Holstein and Montbéliarde dairy cows. This evidence concerns the gene CHL1 and mastitis.