GDF8 was not different amongst healthy cats (2137 ± 740 pg/mL) and cats with IRIS stage 1 (1785 ± 530 pg/mL) and IRIS stage 2 (1961 ± 638 pg/mL; <i>p</i> = 0.608) CKD. The gene discussed is MSTN; the disease is chronic kidney disease.