Acquired urea cycle amino acid deficiency and hyperammonaemic encephalopathy in a cat with inflammatory bowel disease and chronic kidney disease

CASE SUMMARY: A 5-year-old male neutered Persian cat was referred for investigation of a 4 week history of weight loss, inappetence and intermittent vomiting. Chronic kidney disease (CKD) and inflammatory bowel disease were diagnosed, and despite immunosuppressive therapy and assisted enteral nutrition, the cat experienced persistent anorexia, vomiting and severe weight loss. After 2 additional weeks of treatment, the cat developed acute-onset neurological signs associated with severe hyperammonaemia and was euthanased. Plasma amino acid assessment revealed deficiency of several amino acids involved in the urea cycle, including arginine. RELEVANCE AND NOVEL INFORMATION: To our knowledge, this is the first reported case of an acquired urea cycle amino acid deficiency without nutritional deprivation in a cat. Several contributing factors were suspected, including intestinal malabsorption and CKD. This case demonstrates the importance of urea cycle amino acids in feline metabolism and possible necessity for parenteral supplementation, particularly in the context of persistent weight loss despite adequate enteral nutrition.