Overview
The bovine kidneys (renes) are lobated: deep fissures divide their surface into lobes (lobi renales) of varying size, each with its own renal papilla. The lobes are fused in the deep cortex and the medulla, but do not form a common crest. There is no renal pelvis either: in the renal sinus the ureter divides into two major calyces (calices renales majores), which branch into minor calyces; each minor calyx cups one papilla.
Topography
- Right kidney: retroperitoneal, ventral to the last rib and the transverse processes of the first lumbar vertebrae. Its cranial pole sits in the renal impression of the liver. It is elongated and dorsoventrally flattened.
- Left kidney: more caudal and suspended from a fold of peritoneum, so it hangs in the abdominal cavity. The dorsal sac of the rumen pushes it to the right, so that it lies right of the median plane, caudal and ventral to the right kidney; its position changes with rumen fill.
- Both are surrounded by abundant perirenal fat.
Clinical relevance
- Rectal palpation: the left kidney can usually be palpated per rectum, with its lobated surface; of the right one, at most the caudal pole is reached in small cows.
- Pyelonephritis: an ascending infection from the bladder, typical of adult cows after calving; the classic agent is Corynebacterium renale, along with Escherichia coli and Trueperella pyogenes. It presents with haematuria, pyuria, fever and weight loss; the affected kidney enlarges, loses its lobation on palpation and the ureter thickens.
- Renal amyloidosis: marked proteinuria, oedema and large, pale kidneys, often with chronic inflammatory disease.
- Toxic nephrosis: heavy intake of acorns or oak leaves (tannins) and some drugs, such as aminoglycosides, damage the tubules.
- Lymphoma: in enzootic bovine leukosis the kidneys can be enlarged and infiltrated.