Hepatic Neoplasia

• Primary hepatic tumours are rare (less than 1.5% of all canine tumours and 1.0-2.9% of all feline tumours) * However, the liver is a common site of metastatic tumours due to the rich blood supply (hapatic portal vein and hepatic artery)
• In dogs, metastasis to the liver is 2.5 times more likely than primary neoplasia
• In cats, primary hepatobillary tumours are more frequent than metastatic tumours
• Malignant tumours are more common in dogs
• Benign tumours are more common in cats
• Malignant primary tumours include:
  • Hepatocellular carcinoma
  • Cholangiocellular carcinoma
  • Gall bladder carcinoma
  • Haemangiosarcoma
  • Mast cell tumour
  • Hepatic carcinoids (neuroendocrine)
• Benign tumours include:
  • Hepatocellular adenoma (hepatoma)
  • Cholangiocellular adenoma
  • Gall bladder adenoma

Note: Distinction must be made between all hepatic tumours and benign nodular hyperplasia frequently observed in the older canine. The most significant primary tumours in the dog are hepatomas, hepatocellular and cholangiocellular carcinomas and hepatic carcinoids. Hepatocellular carcinomas and cholangiocarcinomas are the most significant in cats.

Diagnosis

Symptomatic in approximately 75% of dogs and 50% of cats, particularly if malignant.

Clinical signs

• Usually non-specific:
  • Weight loss
  • Inappetance
  • Lethargy
  • Polyuria-Polydipsia
  • Vomiting
  • Ascites
• Neurological Signs - seizures, ataxia and weakness occur less frequently. They may be due to metastasis to the central nervous system, hepatic encephalopathy or hypglycaemia which can occur as a paraneoplastic syndrome
• Icterus - Particularly in dogs with extrahepatic cholangiocarcinomas and diffuse carcinoids

Physical Examination

• Cranial abdominal mass - palpable in up to 75% of cats and dogs

Haematology and Biochemistry

• Usually non-specific. The following are frequently observed in dogs:
  • Mild non-regenerative anaemia - cause idiopathic, however, anaemia of chronic disease, inflammation, red blood cell sequestration and iron deficiency may play roles
  • Leukocytosis - resulting from the associated inflammation and necrosis with large liver masses
  • Thrombocytosis - potential causes include production of thrombopoietin as a parneoplastic syndrome, iron deficiency, inflammatory cytokines and anaemia
• Elevated hepatic enzymes - likely due to hepatocellular damage or biliary stasis though the level of enzyme increase is not proportional to severity of liver damage
• Hypoalbuminaemia
• Hyperglobulinaemia
• Hypoglycaemia
• Elevated pre- and postprandial bile acids

• The following have been observed in cats:
  • Azotaemia
  • Elevated hepatic enzymes
  • Elevated bilirubin

Description

Carcinogens and toxins for example nitrosamines can induce hepatic tumours in an experimental environment.

Signalment

• Hepatic carcinoma occurs most often in male dogs over 10 years old
• Cholangiocellular carcinoma occurs more commonly in female cats