Table 2.

Ultrasonographic phenotypic classification of hepatobiliary disorders in dogs.

Disorder	Ultrasonographic features	Pathophysiologic mechanism
Hepatitis	Mild hepatomegaly; decreased echogenicity in acute hepatitis and increased echogenicity in chronic hepatitis; reduced parenchymal uniformity. Vascular margins are more conspicuous in acute hepatitis but become less conspicuous in chronic hepatitis. Mild ascites may be present [7].	Acute inflammation causes congestion and inflammatory cell infiltration, increasing tissue water content, which results in hypoechogenicity.
Hepatic lipidosis	Grade 1: mild diffuse increased hepatic echogenicity; diaphragm and portal vein walls are easily visualized [8].	Lipid accumulation within hepatocytes increases ultrasound backscatter, leading to hyperechogenicity.
		Grade 2: moderate diffuse increased echogenicity with reduced definition of portal vein walls and the diaphragm [8].
		Grade 3: marked diffuse increased echogenicity with poor or absent visualization of portal vein walls, diaphragm, and the far field/posterior aspect of the right hepatic lobe [8].
Cirrhosis	Small liver; irregular margins; markedly increased echogenicity; heterogeneous architecture. Portal vein dilation; ascites may be present [9].	Fibrous tissue deposition causes hepatic contraction and increased echogenicity, and contributes to portal hypertension.