Low Level of Supplemental Dietary L carnitine Increases Energy Expenditure in Overweight, But Not Lean, Cats Fed a Moderate Ener L carnitine is primarily synthesized in the liver from the amino acids lysine and methionine through a series of four enzymatic reactions, with the liver and kidneys converting the precursor butyrobetaine into active napfcheck L Carnitine for dogs and cats Cardiomyopathies in cats Veterinarian Karlsruhe Arndt Small Animal Center Dietary l Carnitine Supplementation in Obese Cats Alters Carnitine Metabolism and Decreases Ketosis during Fasting and Induced Hepatic Lipidosis ScienceDirect