It is the condition of the body to adapt to the effects of substances to the body thus requiring an even larger amount of the substance to experience the same physiological and mental effect.

Your dog can sniff at or even eat a bit of catnip. the herb is edible and not harmful. just don't expect them to roll around like a cat would! your dog may scrutinize catnip by licking and smelling at it, or be totally indifferent to this stimulant.

It hurts for them at first then they get used to it