Colic impression

The colic impression of liver (colic fossa) of the liver refers to the shallow depression formed on the visceral surface of the liver (typically on the right lobe or quadrate lobe depending on the species) due to contact with parts of the colon. This impression varies among domestic animal species based on their gastrointestinal anatomy and the spatial relationship between the liver and surrounding organs, it is mainly seen in humans and horses.

Species-Specific Differences

• Horse (Equine): The colic impression is well-marked and located on the caudodorsal surface of the right lobe of the liver. It is caused primarily by the right dorsal colon and, to some extent, the transverse colon. Given the massive and complex arrangement of the large colon in the horse, the colic impression is prominent.

• Ruminants (Cattle, Sheep, Goats): In cattle and small ruminants, the colon forms a spiral loop and is not as voluminous as in the horse. The liver is mostly displaced to the right by the large rumen. The colic impression is present but less distinct; it is mainly formed by the proximal loop of the ascending colon and sometimes the spiral colon.

• Pig (Swine): Pigs have a large, spiral colon which lies in contact with the liver. The colic impression is relatively pronounced and lies on the caudoventral part of the visceral surface, especially due to the centrifugal coils of the colon.

• Dog (Canine): The colic impression is caused by the transverse colon and is located near the gallbladder fossa on the quadrate and right medial lobes of the liver. It is usually less marked compared to herbivores due to the simpler configuration of the colon.

• Cat (Feline): Similar to dogs, the colic impression is subtle and caused by the transverse colon. It lies in proximity to the gallbladder region on the visceral surface.