Portal venous gas in dogs and cats with severe enterocolitis
Gas densities in the liver on ultrasonography may be found within the parenchyma (emphysematous hepatitis: often associated with necrotic neoplasms), in and around the gallbladder (emphysematous cholecystitis) or in vessels -either biliary tracts (pneumobilia) or portal veins.
Gas in portal veins tends to be carried away from the to the periphery of the liver. This is a transverse view from below the xiphisternum in a Labrador Retriever with severe acute enterocolitis and an adrenal mass. Bright, hyperechoic gas bubbles can be seen within portal vessels travelling away from the hilus.
On still images gas densities are scattered through the liver:
The fact that the gas is predominantly located peripherally is significant: gas in the biliary tracts tends to be carried towards the hilus.
This is the diarrhoea-filled colon:
And the left adrenal mass:
Unsurprisingly, views of the portal vein and tributaries show gas bubbles carried in flow from the mesenteric vein entering the main PV:
This is a little review of the phenomenon in human medicine:
http://radiopaedia.org/articles/portal-venous-gas
As reported, our experience in cats and dogs is that portal vein gas carries a poor prognosis.
This is a fatal enterocolitis with intensely hyperechoic portal venous gas in a cat:
…and detail of a gas bubble in a portal vein:
