Recent research has shown that hypoxia-induced mediators of fibrosis such as hypoxia-inducible factor-1 alpha (HIF-1 alpha), matrix metalloproteinases-2 (MMP2),−7 (MMP7), and−9 (MMP9), tissue inhibitor of metalloproteinase-1 (TIMP1), and transforming growth factor-β1 (TGFB1) are upregulated in feline kidneys with CKD supporting the link between hypoxia-fibrosis-CKD in the cat (14). Here, TIMP1 is linked to chronic kidney disease.