Matrix metalloproteinases (MMPs), tissue inhibitors of metalloproteinases (TIMPs) and transforming growth factor-β (TGF-β) in advanced canine myxomatous mitral valve disease.

•Valvular and myocardial MMP2, MMP14, TGF-β1, TGF-β2 and myocardial TIMP2 and TIMP3 mRNA expression were increased in advanced MMVD.•Plasma MMP9 was decreased in advanced MMVD.•All affected markers correlated to increased echocardiographic parameters.•Narrowed myocardial vessels were associated with increased myocardial MMP2, MMP14, TIMP2 and TIMP3 mRNA expression.•Degenerative processes in MMVD involve MMPs, TIMPs and TGF-βs in both the mitral valve and the myocardium.