It is not advised for you to shampoo your Maine Coon with human shampoo. The acidity levels are different in humans and cats. Human shampoo is more acidic for the cat's skin and may give irritation which leads to flaky skin and risks disease with prolonged use. If you do use human shampoo on your Maine Coon, make sure it is thoroughly rinsed so the cat does not ingest toxic chemicals when grooming themselves.