Overview
The growth of the rumen and reticulum pushes the liver (hepar) to the right, so that in the adult it lies entirely right of the median plane. Its convex diaphragmatic surface rests on the right part of the diaphragm and the right costal wall; its visceral surface contacts the reticulum, omasum, abomasum, duodenum and the right kidney, which sits in the renal impression. The organ is also rotated: the original left lobe lies ventral and cranial, and the right lobe dorsal and caudal.
Lobes and vessels
- Lobes: the fissures are shallow and the lobes are less distinct than in the dog or cat. A left lobe, quadrate lobe, right lobe and caudate lobe are recognised, the last with the papillary process and a prominent caudate process.
- Caudal vena cava: runs along the dorsal border, partly embedded in the parenchyma, before crossing the diaphragm.
- Hilus (porta hepatis): the portal vein and hepatic artery enter and the hepatic duct leaves here.
Biliary tract
- Gallbladder (vesica fellea): present in cattle; pear-shaped, on the visceral surface between the quadrate and right lobes, and projecting beyond the ventral border.
- Bile duct (ductus choledochus): opens at the major duodenal papilla, in the cranial part of the duodenum. In cattle the pancreatic duct opens separately, further caudally.
Clinical relevance
- Liver abscesses: a complication of ruminal acidosis and rumenitis; bacteria, mainly Fusobacterium necrophorum and Trueperella pyogenes, arrive through the portal vein. They are a major cause of condemnation in feedlots. An abscess that erodes the caudal vena cava can cause thrombosis and septic emboli in the lung.
- Fatty liver (hepatic lipidosis): in the transition cow, negative energy balance mobilises body fat that accumulates in hepatocytes. It is worse in over-conditioned cows and is associated with ketosis, displaced abomasum and poorer fertility.
- Fasciolosis: Fasciola hepatica, transmitted by freshwater snails, migrates through the parenchyma and lives in the bile ducts; it causes chronic cholangitis and, in cattle, thickened, calcified bile ducts. Migrating larvae favour infectious necrotic hepatitis caused by Clostridium novyi.
- Examination: the liver lies under the right ribs and cannot be palpated; it is examined by ultrasound and biopsied through a caudal right intercostal space.