Photo by Rick Geary

The cat is goofy and reeling for about ten minutes, the typical length of a catnip high.

Dear Matthew Alice: My Siamese cat discovered a healthy catnip plant in my patio last week. Now every night when I come home from work he is waiting by the patio door. When I let him out, he goes straight to the plant and literally drools over it. Within 15 minutes or so he wants to repeat the exercise. This goes on all night. My other cat wants nothing to do with it. Why is the one cat so obsessed with the mystical weed? Is catnip addicting? Why does it only affect cats — and only certain ones, at that? — Parent of a Feline Flower Child, San Diego

An all-too-common story. Two cats, same upbringing. One’s helping with the dishes and making straight A’s, the other’s beginning the long, slow slide into kitty oblivion. But your household does represent the typical situation for catnip susceptibility in the feline world (including lions and other wild cats). It affects only about half the population, though it’s interesting to note that all kittens are oblivious to it. The susceptibility, if it’s there at all, doesn’t kick in until an animal is about three months old. Catnipmania is definitely a genetic trait. So don’t accuse your Siamese of having a major character flaw. He has the catnip gene and he just can’t help himself.

Catnip (Nepeta cataria) is a member of the mint family, native to Europe and introduced here in Colonial times as a medicinal herb. The volatile oil hepetalactone is the active ingredient.

As you’ve noted, once the cat has snorted a little weed, he’s goofy and reeling for about ten minutes, the typical length of a catnip high. Then it’s back for another hit. Some vets believe catnip mimics the effect of sex hormones. Others disagree. Any biological advantage of the situation for the cat or the plant is yet to be explained. You’ll find the occasional vet with a Reefer Madness mentality who says too much catnip can cause permanent psychosis, but the mainstream opinion is that a little herb from time to time docs no harm. Some vets even use it to keep cats from fearing office visits. Oddly, when sniffed, catnip is a stimulant; ingested it’s a tranquilizer. No one’s explained that either. I doubt that scare tactics (“This is your brain. This is your brain on catnip”) or “Just say meow” campaigns will do any good. So stock up on Grateful Dead records and live with it.