Association between hepatic histopathologic lesions and clinical findings in dogs undergoing surgical attenuation of a congenital portosystemic shunt: 38 cases (2000-2004).

OBJECTIVE: To review hepatic histopathologic lesions in dogs undergoing surgical attenuation of a congenital portosystemic shunt (CPSS) in relation to clinical findings and tolerance of complete surgical attenuation.
DESIGN: Retrospective case series. ANIMALS: 38 dogs that underwent surgical attenuation of a CPSS. PROCEDURES: Hepatic histologic examination findings and medical records of dogs undergoing surgical attenuation of a single CPSS between August 2000 and July 2004 were reviewed. Liver biopsy specimens were obtained from 38 dogs during surgery prior to complete (n = 16) or partial (22) attenuation of a CPSS and from 13 of the same dogs a median of 3 months following surgical attenuation.
RESULTS: Portal tracts were inadequate for interpretation in 2 liver biopsy specimens. Liver biopsy specimens obtained prior to surgical attenuation of a CPSS had a lack of identifiable portal veins (13/36 dogs), hepatic arteriolar proliferation (25/36), ductular reaction (5/36), steatosis (16/38), and iron accumulation (32/38). Lack of identifiable portal veins on histologic examination was associated with increased hepatic arteriolar proliferation, decreased tolerance to complete surgical CPSS attenuation, and decreased opacification of intrahepatic portal vessels on portovenography. Ductular reaction was always associated with failure to tolerate complete surgical attenuation of a CPSS. Surgical CPSS attenuation resulted in significant clinical, serum biochemical, and portovenographic changes indicative of improved liver function, but only subtle changes in hepatic histologic examination findings. CONCLUSIONS AND CLINICAL RELEVANCE: Dogs without identifiable intrahepatic portal veins that had a ductular reaction on hepatic histologic examination were less likely to tolerate complete attenuation of a CPSS.