If you're a cat lover, you know that your furry friends can go absolutely wild for a sprinkling of catnip, the green herb that can be found in many cat toys or even grown in your own garden.

Does your cat, an otherwise aloof and graceful creature, go whacky for catnip? Then they are one of the 70 per cent of domestic cats, as well as some big cats like lions, who do. But how has this ...