Proteinuria (UP/C > 0.5) was observed in 7 out of 13 CKD dogs with stage 3, and a tubular pattern characterized by the predominance of low molecular weight proteins loss (RBP and or VDBP) was noticed in 5/7, and the loss of albumin and RBP, both in similar magnitude, in 2/7 (tubular and glomerular pattern).