Lobular dissecting hepatitis in the dog.

Ascites and acquired portosystemic shunts were consistent findings in six dogs with a chronic hepatitis of unusual morphology and unknown etiology. The hepatitis was characterized by a mixed inflammatory infiltrate and dissection of the lobular parenchyma by reticulin and fine collagen fibers. While limiting plates were disrupted by this process, portal inflammation was inconstant and seldom marked. Biopsy samples generally had very small, sublobular regenerative nodules, but larger nodules sometimes were present postmortem. Dilated vascular channels, representing sinusoids and portal venous radicles were a prominent feature of most affected livers. The lesions differ from previously documented chronic hepatitis in the dog, and from the chronic hepatitides in man.