A male, 12 months old, Friesian breed  calf shows a bilateral alteration of the kidneys. The right one presents a vesicle of purulent material and adhesions to the liver.

When opening the left kidney, a dilatation of the renal pelvis is observed, which is intensely fibrous and has abundant purulent content mixed with material of sandy consistency. As a consequence of these alterations the renal medula is atrophied. The inspectors that refer the case suspect a congenital malformation.

The histopathological study shows that it is a chronic suppurative pyelonephritis. A diffuse and inflammatory sclerosing (fibrosis) reaction of the renal pelvis with a presence of mineralized material and abundant bacteria is confirmed.

Bacterial pyelonephritis usually have an ascending origin (the bacteria enter through low urinary tracts) the presence of bacteria favors the precipitation of mineral salts and the formation of calculi.

Bilateral alteration of the kidneys, in the right (arrowhead), a bag of purulent material  was observed wich was adhered to the liver.

Image of the left kidney sectioned in half. You can see dilatation and fibrosis of the renal pelvis and the presence of suppurative material.