Catnip is often referred to as 'weed for cats' – but scientists say there is another little-known plant that sends felines into even more of a frenzy. Researchers say that silver vine (scientifically known as Actinidia polygama) gives cats an even bigger buzz.
Both plants contain similar chemical compounds that activate cats' opioid reward systems, triggering an instant, harmless kick of euphoria. While catnip contains more of these active chemicals, a new study has revealed that cats have a significant preference for silver vine.
Although silver vine isn't well known in the West, it has been recognised as a cat-attracting plant for hundreds of years in Japan, where it is called matabi. In their new study, scientists from Iwate University and Nagoya University in Japan offered cats a choice between the plants. They found that both free-roaming outdoor cats and purebred indoor cats almost always went for silver vine. In fact, most cats completely ignored the scientists' catnip offering whenever silver vine was also available.
How Catnip and Silver Vine Affect Cats
As many pet owners will know, when felines encounter catnip, they usually flop to the floor, rolling around and rubbing their faces into the plant. Catnip contains a chemical called nepetalactone, while silver vine contains a very similar compound called nepetalactol. Scientists believe that cats have special cells in their airways that react with these chemicals when they are sniffed through the nose. This triggers the opioid reward systems to start producing endorphins – the cat's natural happy chemicals.
This doesn't necessarily make cats 'high' in the same way that drugs like cannabis affect humans, but it does put them in a good mood and significantly alter their behaviour. While these effects are well-documented, scientists haven't previously studied what happens when cats encounter catnip and silver vine at the same time.
Study Findings: Cats Prefer Silver Vine
In their first trial, the researchers placed fresh silver vine branches near a live catnip plant in a garden that was frequented by local cats. Six cats visited the garden over 10 nights, five of which rubbed and rolled on the silver vine, while no cats showed any interest in the catnip. When the researchers repeated the test only using extracts from the two plants, cats still showed a strong preference for the silver vine extracts.
To check that this behaviour wasn't unique to this small population of Japanese cats, researchers repeated the test with 22 cats from Europe, the US, and the Middle East. Once again, when catnip and silver vine extracts were offered, 15 cats only responded to the silver vine extract, while only three responded to the catnip. This is despite the fact that cats would show the normal rubbing and rolling behaviour when given samples of catnip in isolation.
Co-author Dr Reiko Uenoyama, an assistant professor at Iwate University, says: 'Our study shows that what cats can respond to and what they actually choose are not always the same. Catnip can make cats respond in laboratory tests, but that does not mean cats will choose it in a more natural, free-choice setting.'
Why Silver Vine Wins
What made these results so unexpected was the fact that fresh catnip plants contain 170 times more active compounds than silver vine. Lead author Professor Masao Miyazaki, of Iwate University, says: 'At first glance, this was counterintuitive. One might expect a plant containing more active compounds, and compounds that clearly work in laboratory tests, to trigger a stronger behavioural response.'
One possible explanation for this unexpected choice is that fresh catnip is simply too strong for most cats to enjoy. When they encounter a living plant or potent extract, the odour might overwhelm their sensitive noses and lead them to choose the more mellow scent of silver vine. Interestingly, this supports an observation from one of the very first accounts of catnip's attractive powers. In 1786, over 200 years ago, Philip Miller noted in his book 'The Gardener's Dictionary' that cats tended to prefer catnip when it was 'withered' and avoided healthy clumps of the plant. This could be because slightly dried-up catnip releases fewer active chemicals, making its scent less overpowering. That could also explain why cats respond so well to dried and powdered catnip products that are often sold as toys.
Other Plants That Affect Cats
Researchers found three other plants have a similar effect to catnip: silver vine, Tatarian honeysuckle, and valerian root. The results of the experiment revealed that 79 per cent of the cats responded positively to silver vine, compared to 68 per cent for catnip. About half of all the cats in the study responded positively to Tatarian honeysuckle and valerian root.
