Multidisciplinary Surgical Treatment of Hepatic Abscess in a Geriatric Dog with Congenital Extrahepatic Portosystemic Shunt.

Hepatic abscesses are uncommon in dogs and typically develop secondary to biliary tract disease or ascending bacterial infections. Although congenital extrahepatic portosystemic shunt (EHPSS) is known to impair hepatic perfusion and immune clearance, its potential role in predisposing geriatric dogs to hepatic abscess formation has not been previously reported. This case report describes the diagnostic approach, therapeutic decision-making, and clinical outcome of a geriatric dog in which a multidrug-resistant hepatic abscess occurred in association with congenital EHPSS, and to propose a pathophysiologic link between chronic portal hypoperfusion and intrahepatic infection. An 11-year-old neutered male Maltese dog with a known EHPSS presented with acute anorexia and lethargy. Diagnostic imaging revealed a hepatic abscess adjacent to the gallbladder, and cytology confirmed a septic process. Despite targeted meropenem therapy based on antimicrobial susceptibility testing, the abscess failed to regress and C-reactive protein levels continued to rise. Concern for persistent biliary contamination and impaired hepatic immune clearance led to surgical intervention. A combined procedure-partial hepatic lobectomy, cholecystectomy, and shunt attenuation-was performed. Postoperative hypotension was managed successfully with vasopressors and transfusion. The patient recovered uneventfully, and at four-month follow-up, hepatic enzyme activities normalized and liver size increased. These findings highlight the need to evaluate hepatic infections in dogs with EHPSS as a potential consequence of impaired hepatic immune clearance rather than an incidental finding.