Why catnip affects some cats and not others
Catnip’s scent carries nepetalactone, a chemical that can trigger a distinctive response in sensitive cats. When a cat sniffs the plant, the molecule reaches smell receptors in the nose. Those receptors send signals to the brain, which can produce behaviors such as rubbing, rolling, or playful bursts of activity. The reaction is not simply a matter of liking the plant: it depends on how the cat’s sensory system responds to the chemical.
Sensitivity is the key difference
Cats vary in whether they have the inherited sensitivity needed to respond. A cat without it may smell catnip and move on, much as a person might notice a scent without finding it especially compelling. That difference explains why two cats can encounter the same dried leaves and behave as if they have met entirely different plants.
Age matters, too. Many kittens do not react when they are very young; the response may emerge as they mature. A kitten’s indifference, therefore, does not necessarily predict how it will respond later.
A sniff is not a reliable test
The effect also depends on the encounter: a cat has to smell enough of the active compound for its response to be noticeable. But a lack of theatrics does not mean the herb has failed or that the cat is being fussy. Catnip sensitivity is a biological variation, not a universal feline trait. For owners, the practical result is simple: a toy that sends one cat tumbling may barely register with a housemate, while a young cat’s first unimpressed sniff may not be its last.
