Catnip, scientific name Nepeta cataria, is a plant of the Lamiaceae or mint family. It can be found cultivated or growing wild in North America and many other places in the world. It is an herbaceous perennial that grows to about 20-40 inches tall and wide with a square stem and brownish-green, coarse-toothed triangular to ovate leaves. The flowers are both showy and fragrant usually white and spotted with pale purple or pink, a nice addition to any garden.

The active ingredient is an essential oil, nepetalactone, and can be isolated by steam distillation. Nepetalactone is a known repellent for mosquitos, cockroaches and termites. It is reportedly 10 times more effective against mosquitos than DEET, the active ingredient in most insect repellents but, unfortunately, is not very effective when applied to the skin.

Nepetalactone attracts cats, not only domestic cats. Tigers, leopards and lynxes have all been shown to react to catnip the same as domestic cats, lions less so. When your cat senses the bruised leaves or stems, it will rub on it, roll in it, paw at it, lick and chew it and display intense playful behavior. If the cat consumes the plant it may demonstrate anxiety or leap about while purring. Some cats will play growl, meow, scratch or bite at you if you are holding the plant material. They may become extremely hyperactive, running and jumping and aggressive if you try to take the “toy” away from them. After the cat loses interest in the catnip, it may take as long as a couple of hours for the animal to “reset” and evidence interest again.

The nepetalactone is detected by the cat via their olfactory epithelium by binding to one or more olfactory receptors. The euphoria wears off in 5 to 15 minutes, then the cat will become non-responsive, just sitting and staring into space. If too much of the material in ingested, the cat may become mellow, drool and fall asleep. Only about two-thirds of cats respond to catnip. The others seem to ignore it and the typical response behavior seems to be hereditary. Other plants including Veleriana officinalis, Acalypha india (only the root) and plants that contain actinidine or iridomyrmecin will have similar effects on susceptible cats. When a responsive individual feline smells the catnip, getting “high” from the smell seems to compel it to react in the same manner every time.

Researchers are uncertain about the neurological explanation for nepetalactone’s effect on cats. One theory is that the substance mimics so-called “happy pheromones” and stimulates specific receptors in the olfactory bulb, the amygdala and/or the hypothalamus in the brain.

While cats can become hyperactive when exposed to catnip, they are by nature survivors and know their limits. Most cats will back away once they have had enough so the substance is not toxic to cats. However if you have both dogs and cats in your house and allow your dog to walk through some Nepeta sp. your cat may pursue the dog with the intention of chewing or rubbing against any part of your dog that has come in contact with the plant material.

— By Dr. David Gross

Dr. David Gross of Edmonds graduated from Colorado State University’s veterinary school in 1960 and was in private practice for 10 years. He retired in 2006 as Professor and Head of Veterinary Biosciences, at the University of Illinois, Urbana-Champaign. Dr. Gross is the author of “Animals Don’t Blush,” which describes the unique patients and even more unique clients of a veterinary practice in Sidney, Montana in the early 1960s.