The Feline Fascination with Silver Vine
Catnip is often referred to as ‘weed for cats’ – but scientists have discovered another plant that sends felines into an even greater frenzy. Researchers have found 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 recognized 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.
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.
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.
Does Catnip Get Cats High?
After smelling catnip, most cats will show changes in their behaviour. Most will roll around, make loud noises, and some may be excited or hyperactive. This is because active chemicals in catnip activate the cat’s opioid reward systems, which control the natural release of endorphins. While this makes cats happy, they are not really ‘high’ in the sense we would think about it.
Cats don’t display any slowed reactions, impaired judgement, or experience any altered perceptions. Likewise, cats can’t get addicted to catnip or suffer withdrawal symptoms if they stop using it. Scientists think this love for catnip actually evolved because the plant acts as a natural mosquito repellent.
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.’
Unexpected Results
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.
Professor Miyazaki told the Daily Mail: ‘silvervine can be a useful form of olfactory enrichment for cats, especially for cats that do not respond to catnip. It may encourage play, rubbing, rolling, and exploratory behavior. Based on our research, silvervine appears to be safe when used appropriately as a cat enrichment material.’
Other Plants with Similar Effects
Scientists have discovered three other plants that have the same effect as catnip:
- Silver Vine: Actinidia polygama is a deciduous climbing vine grown in the high mountainous regions of eastern Asia. It produces clusters of fragrant, creamy white 1 ½ inch flowers which bloom in the summer and bears a fruit similar to kiwi. Silver vine has been used for centuries in Asia as a preventative health aid. It is very popular in Japan and China as a cat stimulant when ground into a powder and has a distinctive sweet tea-like fragrance which attracts cats.
- Tatarian Honeysuckle: Native to Siberia and other parts of eastern Asia, but it is probably better known in North America, where it is a widespread introduced species and noxious weed. A bushy shrub, it can grow to three meters in height. It generally has a pair of white to pink crimson red flowers.
- Valerian Root: A perennial flowering plant, with heads of sweetly scented pink or white flowers that bloom in the summer and can reach a height of 5 feet. Valerian flower extracts were used as a perfume in the 16th century. It is also widely used, when crushed, as a herbal remedy. It’s been used to treat sleep disorders and for conditions connected to anxiety and psychological stress including nervous asthma, hysterical states, hypochondria and headaches.
