High-Yield Points:
• Two retroperitoneal organs in sublumbar region.
• Cattle kidney = externally lobulated; sheep and goat kidneys are externally smooth.
• Right kidney: cranial and fixed against the dorsal abdominal wall, contacting the liver. Left kidney: displaced to the right by the rumen and relatively pendulous/less fixed; 'floating kidney' is only a descriptive clinical shorthand.
• Functional unit = nephron. No single renal pelvis in ox — calyces drain directly into ureter.
• Ureter passes caudally over psoas muscles → opens into bladder at trigone.
• Palpable per rectum in cow (left kidney especially).

Ruminant Urinary System

Bovine Kidneys: In cattle, fetal lobation persists externally, producing approximately 15-20 visible lobes separated by grooves. This is characteristic of cattle among the principal domestic ruminants; sheep and goat kidneys are externally smooth.

Right kidney: Lies under the last rib and first 2-3 lumbar transverse processes; relatively fixed; bears a clear impression on the caudate lobe of the liver.

Left kidney: The rumen displaces it to the right of the median plane. Unlike the firmly retroperitoneal right kidney, it is pendulous and enclosed in a peritoneal fold except at its attachment, so its position varies with rumen fill and body size. It is commonly palpable per rectum in the adult cow.

Internal Structure: Ox kidney is multipyramidal — many renal pyramids, each with its own papilla draining into a calyx. There is NO renal pelvis in ox; instead the calyces directly converge to form the ureter.

Ureter: Long muscular tube descending from the renal hilus along the dorsal abdominal wall (retroperitoneal), crosses the pelvic brim, and enters the dorsal bladder wall obliquely at the trigone — this oblique entry acts as a one-way valve preventing reflux during bladder distension.