History:

• A 13.5- year-old, male neutered, domestic shorthair cat presented for not eating or drinking, and lethargy for 4 days.
• There was no prior medical history and the patient was reported to be in good health.

Physical exam/Bloodwork

• Pertinent physical exam findings included generalized icterus and hepatomegaly on abdominal palpation. The patient had a body condition score of 6/9 and a muscle condition score of 1/3.
• Initial blood work revealed a mild anemia, mild leukocytosis characterized by a neutrophilia, panhypoproteinemia, elevated ALP (657 U/L), ALT (269 U/L), and hyperbilirubinemia (7.0 U/L). The GGT was normal (4 U/L).

Additional imaging:

• An abdominal ultrasound showed a diffuse hepatopathy characterized by enlargement and hyperechogenicity. Choledochitis was thought possible due to mild dilation of the common bile duct and slight thickening of the wall. There was also a segmental enteropathy and small volume of peritoneal effusion.
• An abdominocentesis was performed.The peritoneal effusion was consistent with a chylous effusion containing relatively low numbers of atypical cohesive cells concerning for carcinoma.

Thoracic and abdominal CT was performed to screen for neoplasia.

CT FINDINGS:

• The liver is moderately to severely diffusely enlarged, with rounded caudal margins. Prior to intravenous contrast administration, the hepatic parenchyma is diffusely markedly hypoattenuating (-25 to -50 HU). Bile within the gallbladder is comparatively hyperattenuating (40-50 HU). No hepatic nodules or masses are identified.
• A mild to moderate volume of peritoneal effusion is present. Multiple thin linear wisps of soft tissue attenuation are within the caudoventral abdominal and inguinal fat.
• Evidence of mild bilateral chronic nephropathy and mild jejunal lymphadenopathy was also noted.
• The patient has a large accumulation of subcutaneous and falciform fat but also has a reduced overall muscle mass.

CT DIAGNOSIS:

• The enlarged and diffusely fat attenuating liver is consistent with hepatic lipidosis.
• Mild to moderate volume of peritoneal effusion is consistent with the recently diagnosed chyloperitoneum.
• Mild caudoventral abdominal and subcutaneous edema is likely secondary to panhypoproteinemia or vasculitis.

CASE DISCUSSION:

• Cytology of the liver confirmed hepatocellular aspiration with marked lipid vacuolization and evidence of cholestasis. No evidence of neoplasia was identified.
• During hospitalization, the patient became progressively neurologically inappropriate and dull despite medical management. He ultimately went into cardiac arrest and could not be revived.
• NECROPSY:
  • The liver was found to be markedly enlarged. The lobe edges were rounded and there was a marked, diffusely enhanced reticular pattern throughout the parenchyma. Sections of the liver floated in formalin supportive of hepatic lipidosis. An impression smear of the liver further confirmed this diagnosis.
• Hepatic lipidosis is one of the most common feline hepatobiliary disorders. It can be idiopathic or secondary to a separate disease process, such as pancreatitis, neoplasia or gastrointestinal disease. Partial or complete anorexia for a week or longer leads to increased peripheral lipolysis secondary to stimulation of hormone sensitive lipase. Lipolysis induces a dramatic increase in the concentration of the free fatty acids in the blood, which accumulates within the liver. The accumulation of triglycerides within hepatocytes results in hepatocyte enlargement, cholestasis and ultimately liver failure. Expected physical exam findings typically include hepatomegaly, jaundice, dehydration, and weight loss. Hepatic encephalopathy is rare but possible. Clinicopathologic changes are characterized by hyperbilirubinemia and increased serum ALT, AST, and ALP, with only a small, if any, increase in GGT activity1. In human medicine, measuring liver attenuation on computed tomography provides a noninvasive method of predicting fat content in the liver in patients with steatosis and steatohepatitis2. A study investigating the clinical application of computed tomography for the diagnosis of feline hepatic lipidosis reported two patients suspected to have hepatic lipidosis, based on clinical signs and bloodwork changes. The patients had lower liver attenuations (27-32.2HU) compared to 26 healthy control cats 54.7 /- 5.6 HU. One cat with a hypoattenuating liver (32.2 HU) showed a mild increase (39 HU) in liver attenuation on follow up CT three weeks later, following clinical recovery. The researchers went on to include a prospective study, which measured liver attenuation of 6 healthy feline patients before and after a fasting period of 72 hours. CT liver attenuation was found to decrease during the fasting period (from 53.8 /- 3 HU prior to fasting to 46.8 /- 2.4 HU after) and then increased after restarting feeding (50.2 /- 3.6 HU)3. Given the recently reported increased potential for major bleeding following ultrasound guided liver biopsy in feline patients with a diagnosis of hepatic lipidosis (add citation), CT may be considered as a non-invasive procedure to aid in the diagnosis.

1. Center SA. Feline hepatic lipidosis. Vet Clin North Am Small Anim Pract 2005; 35: 225-269.
2. Kodama Y, Ng CS, Wu TT, Ayers GD, Curely SA, Abdalla EK, Vauthey JN, Charnsangavej C. Comparison of CT methods for determining the fat content of the liver. AJR Am J Roentgenol 2007; 188: 1307-1312 [PMID:17449775 DOI:10.2214/AJR.06.0992].
3. Nakamura M, Chen HM, Momoi Y, Iwasaki T. Clinical application of computed tomography for the diagnosis of feline hepatic lipidosis. J Vet Med Sci 2005, 67, 1163-1165.
4. Pavlick, M., Webster, C. R. L., & Penninck, D. G. (2018). Bleeding risk and complications associated with percutaneous ultrasound-guided liver biopsy in cats. Journal of Feline Medicine and Surgery, 21(6), 529–536. https://doi.org/10.1177/1098612×18788883