Warning Signs of Fatty Liver in Cats: Early Signs and Treatment Options Veterinary Secrets with Dr. Andrew Jones, DVM 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 PDF) L carnitine in petfood My 4 month old girl Margo was diagnosed with polyneuropathy last week. Neurologist has recommended L carnitine as a supplement. She's better than she was but not climbing or jumping yet x