The comparative analysis of CYP transcripts in L4 of H. contortus revealed higher constitutive expression of 12 cyp genes (HCON_0044070, HCON_0073880, HCON_0073890, HCON_00134870, HCON_0023990, HCON_0024000, HCON_0024005, HCON_0024010, HCON_00145460, HCON_00145170, HCON_0042000, HCON_00141052) in the resistant BSI isolate compared to the susceptible McMaster isolate. This evidence concerns the gene PPIG and bathing suit ichthyosis.