Renal fascia

The renal fascia (also called the perirenal fascia or Gerota’s fascia in human anatomy) is a layer of connective tissue that envelops the kidney and the perirenal fat. It forms part of the retroperitoneal space and acts to suspend the kidney within the abdominal cavity.

It typically has two main layers:

• Anterior layer (prerenal fascia)

• Posterior layer (retrorenal fascia)

These layers encapsulate the perirenal (adipose) capsule, which surrounds the renal capsule (the fibrous layer tightly adherent to the kidney itself).

Species-Specific Considerations

a. Dog and Cat (Carnivores)

• The renal fascia is well developed.

• It blends with the transversalis fascia of the abdominal wall and the diaphragmatic fascia cranially.

• The kidneys are retroperitoneal, and the fascia helps maintain their relatively fixed position, especially the right kidney which is more cranial and more tightly bound.

b. Horse

• The kidneys are asymmetrically placed, with the right kidney more cranial and closely associated with the liver.

• The renal fascia is more tightly adherent around the right kidney, aiding in this asymmetry.

• It is continuous with the fascia of the diaphragm and helps anchor the kidneys against displacement from peristalsis or abdominal pressure.

c. Ox (Cattle)

• Kidneys are displaced caudally (especially the left kidney, which is located near the midline or even on the right side due to the large rumen).

• The renal fascia is less distinct and looser than in carnivores, reflecting the kidney’s more mobile nature.

• The lack of a strong fascial fixation allows the left kidney to be displaced across the midline.

d. Pig

• The renal fascia is fairly distinct and envelops the perirenal fat, but pigs also have lobulated kidneys, and the fascia helps hold the lobules together.

• The kidneys are located more symmetrically compared to ruminants.

Relations and Continuities

• The renal fascia merges cranially with the diaphragmatic fascia.

• Laterally and posteriorly, it connects with the fascia of the abdominal wall.

• Medially, it may be continuous with the adventitia of the renal vessels and ureter.

• Inferiorly, it may be incomplete, allowing communication with the pelvic retroperitoneal space.