Overview

• Bacterial infection involving the hepatobiliary system; variable in size and distribution.
• Distribution and lobular involvement-variable; multifocal microabcessation; diffuse suppurative cholangitis/cholangiohepatitis; cholecystitis; choledochitis, or discrete focal necrosuppurative lesions; lesions associate with pyogenic bacteria.
• Large abscesses commonly associate with hepatocellular carcinoma (HCA) in dogs where opportunistic organisms populate necrotic regions.

Signalment

• Dog and cat.
• No breed predilection.
• Hepatic abscesses-most common in old dogs with HCA in necrotic foci, or secondary to immunosuppression or diabetes mellitus; in neonates may develop subsequent to omphalitis.
• Suppurative septic cholangitis/cholangiohepatitis-most common in young-middle-aged male cats secondary to retrograde bile duct infection or hematogenous distribution of translocated enteric bacteria via the portal vein.
• Cholestatic disorders (e.g., EHBDO, GB mucocele) predispose to enteric bacterial translocation due to reduced delivery of bile acids and secretory IgA (normally regulate the enteric bacterial population and reduce enteric bacterial translocation); cholestasis also impairs canalicular bacterial egress from the liver.

Signs

Causes & Risk Factors

• Hematogenous infection via the portal vein, hepatic artery, or umbilical vein.
• Biliary tree obstruction, preexisting hepatobiliary or pancreatic disease, and inflammatory bowel disease: predispose to enteric bacterial translocation.
• Ascending biliary tract infection.
• Cholecystoenterostomy.
• HCA with necrotic foci.
• Compromised immune responses: diabetes mellitus, glucocorticoid administration, hyperadrenocorticism, hypothyroidism, chemotherapy, immune-mediated disorders managed with immunosuppressives.
• Penetrating wounds.
• Complication of hepatic biopsy or other surgery.

Differential Diagnosis

• Infectious or necroinflammatory disease-most patients are febrile.
• Hepatic abscess-fever, abdominal pain, and/or hepatomegaly (especially if risk factors).
• Pancreatitis or pancreatic abscess.
• Hepatobiliary neoplasia.
• Gastrointestinal obstruction or perforation.
• Peritonitis or other intra-abdominal abscess.
• Cholecystitis, choledochitis, cholelithiasis.

CBC/Biochemistry/Urinalysis

• CBC-neutrophilic leukocytosis with a left shift and toxic WBC changes; monocytosis; thrombocytopenia; nonregenerative anemia.
• Biochemistry-variably increased ALT > ALP activity; low albumin, hyperglobulinemia, inconsistent hyperbilirubinemia, and hypoglycemia; features reflecting endotoxemia (Gram-negative bacterial infection.
• Urinalysis-usually normal; bilirubinuria; proteinuria; culture may or may not disclose hematogenously dispersed organisms.

Other Laboratory Tests

• Serum bile acids-may be high; depends on the extent or zonal location of hepatic involvement, cholestasis, or may reflect sepsis-related cholestasis.
• Coagulation tests and RBC morphology (schistocytes)-consistent with DIC.

Imaging

Diagnostic Procedures

Drug(s)

• Antibiotics-initially based on cytology and Gram stain, then adjusted based on culture and sensitivity results; continue for 2–4 months, perhaps longer.
• Initial treatment-combine antimicrobials to cover possible polymicrobial infection (common aerobic and anaerobic pathogens); common effective empirical combination includes: ticarcillin (25–50 mg/kg over 15 min. CRI) or amoxicillin clavulanate (10–20 mg/kg PO q12h), enrofloxacin (2.5 mg/kg PO or SC q12h dogs or cats; may use 5 mg/kg PO or SC q12h in dogs), and metronidazole (15 mg/kg IV q12h; reduce dose by 50% if hepatic dysfunction or severe cholestasis) or clindamycin (10–16 mg/kg SC per day; reduce dose if hepatic dysfunction or severe cholestasis to 5 mg/kg SC per day).
• Choleretics advised if biliary tree involved, but if EHBDO NOT UNTIL biliary decompression (see Bile Duct Obstruction (Extrahepatic); Cholangitis/Cholangiohepatitis Syndrome).
• Antioxidants advised (see Chronic Hepatitis).

Contraindications

• Aminoglycosides-do not use until normal hydration because of potential for renal injury; also, may not penetrate abscess capsule.
• Avoid drugs metabolized or excreted by the liver or those known to be hepatotoxic if compromised liver function; adjust dosages or frequency of drugs if suspect reduced hepatic elimination, cholestasis, or hepatic dysfunction.

Patient Monitoring

• Assess vital signs and physical condition.
• Sequential ultrasound examinations-monitor for abscess recrudescence or suppurative peritonitis.

Possible Complications

• DIC
• Septicemia/Endotoxemia
• Fulminant hepatic failure
• Septic peritonitis
• Acute renal failure

Expected Course and Prognosis

• Favorable prognosis-early detection and aggressive antimicrobial treatment, with judicious surgical intervention.
• Guarded prognosis-concurrent disorders, especially unresectable primary hepatic neoplasia.

Abbreviations

• ALP =alkaline phosphatase
• ALT = alanine aminotransferase
• AST = aspartate aminotransferase
• CCHS = cholangitis/cholangiohepatitis syndrome
• CRI = constant rate infusion
• EHBDO = extrahepatic bile duct obstruction
• GB = gallbladder