Liver Problems? One solution, three choices. Zentonil is a new stable form of S-Adenosylmethionine (SAMe), a compound that is vital to normal liver function. S-Adenosylmethionine has been clinically proven in veterinary trials to safely and effectively support and protect liver cells in compromised animals. ZENTONIL is the only S-Adenosylmenthionine product on the veterinary market that is offered in three strengths for greater: Dosage accuracy Ease of administration Cost-effectiveness