Effect of Parenteral Amino Acid Composition on Hyperammonemia in a Cat with Hepatic Lipidosis

An 8 yr old spayed female domestic shorthair presented with a 1 wk history of anorexia and lethargy. Cytological examination of the liver using fine-needle aspiration revealed numerous adipocytes, confirming hepatic lipidosis. The cat was hospitalized for treatment; subsequently, the clinical signs and blood analysis results improved. On day 17, the nasoesophageal tube was removed because of recovery of appetite and vitality. However, owing to insufficient voluntary food intake, partial parenteral nutrition (PPN) was initiated using an amino acid solution with a low branched-chain amino acid (BCAA)/aromatic amino acid (AAA) ratio and arginine deficiency. Within 24 hr of PPN administration, neurological signs were observed, including vocalization, panting, hyperactivity, and a subsequent comatose state. Although hepatic encephalopathy was considered, there was limited evidence of hepatic failure. The clinical course was most consistent with acute hyperammonemia secondary to arginine deficiency, although a contributing role of the low BCAA/AAA ratio cannot be excluded. This case suggests that amino acid PPN with arginine deficiency and a low BCAA/AAA ratio may contribute to neurological signs in cats, underscoring the importance of careful amino acid selection in nutritional formulations.