Ultrasonogram of Hepatic Abscess in Cattle inoculated with Fusobacterium necrophorum

Abstract

Fusobacterium necrophorum was inoculated into the portal vein of eight cattle. Multiple necrotic foci were found in the livers of three of them which died acutely. The remaining cattle autopsied 12 to 126 days after the inoculation had abscesses in their livers. In the former three cattle, multiple hyperechoic masses were detected in the liver by ultrasonography. The masses corresponded to the necrotic foci. In the latter five cattle, a liver lesion was similarly detected, first on the 5th to 10th day after inoculation. It consisted of a central hyperechoic mass and a surrounding hypoechoic halo, which corresponded to necrotic tissue and granulation tissue, respectively. In some cases the central hyperechoic area of the halo pattern changed later to be hypoechoic. The ultrasonographic lesions appeared as a spherical hypoechoic pattern. Finally, they disappeared from the hepatic images on around the 50th to 70th day after inoculation. These processes corresponded to diminution of the central necrotic mass, the abscess being gradually replaced by the granulation tissue and capsule and to change of the abscess into the scar. The capsule and scar were imaged as a isoechoic or hypoechoic pattern. Some other lesions of the halo pattern remained and were accompained by lateral shadows.