Just in time for summer, scientists share both intoxicating and mosquito-repelling plants for cats
By Kim Campbell Thornton
Andrews McMeel Syndication
We’ve all seen cats rolling in ecstasy when exposed to catnip (Nepeta cataria) or silver vine (Actinidia polygama), another feline intoxicant endemic to Japan and China. The kitty feel-good herbs activate the opioid system, producing a euphoric effect. But do they have another purpose?
Researchers at Iwate University in Japan, in partnership with scientists at Nagoya University in Japan and the University of Liverpool in the U.K., wanted to uncover the neurophysiological mechanism and biological function of the silver vine response in domestic cats. It turns out that licking and chewing these plant leaves is a feline form of chemical pest defense, transferring plant metabolites known as iridoids, which repel mosquitoes, to their fur.
The mosquito repellent effect of the chemical compound nepetalactone in catnip was already known. And researchers at Northwestern University in Chicago and Lund University in Sweden discovered last year that it’s because nepetalactone activates an irritant receptor called TRPA1, found in animals ranging from flatworms and fruit flies to humans.
“We now think catnip is so aversive to so many insect species because it activates this widespread irritant receptor,” said Marco Gallio, associate professor of neurobiology at Northwestern’s Weinberg College of Arts and Sciences, in a news release last year.
The Japanese researchers sought to learn whether nepetalactol -- the active compound in silver vine (Actinidia polygama) -- would have the same effect. They had observed that when cats licked and chewed silver vine, the crumpled and torn leaves were more aromatic than intact leaves.
Working with 16 domestic shorthairs, the scientists learned that when cats lick, chew, rub and roll on silver vine, much higher amounts of the insect repellents are released. The damage to the leaves produces a complex “cocktail” of iridoids that is more repellent to mosquitoes.
The study, published recently in the journal iScience, demonstrated that the silver vine response is regulated via the same opioid receptors involved in rewarding and euphoric effects in humans. The rubbing and rolling response transfers nepetalactol from the plant leaves onto the cat’s face and head, providing a protective effect against Aedes albopictus mosquitoes (tiger mosquitoes), revealing its likely biological significance.
In an email interview, Dr. Masao Miyazaki of Iwate University, a leader of the research project, explained that not only were more iridoids released, but their composition changed in ways that seemed to encourage the cats.
“Nepetalactol accounts for over 90% of total iridoids in intact leaves, but this drops to about 45% in damaged leaves as other iridoids greatly increase,” says Miyazaki, whose research interests include how chemicals drive instinctual behaviors of companion animals. “The altered iridoid mixture corresponding to damaged leaves promoted a much more prolonged response in cats.”
To test whether the cats were reacting to these compounds specifically, the cats were presented with dishes containing pure nepetalactone and nepetalactol. “Cats show the same response to iridoid cocktails and natural plants except for chewing,” Miyazaki says. “They lick the chemicals on the plastic dish and rub against and roll over on the dish.”
The behavior continued even after the dishes were covered with a punctured plastic cover, preventing the cats from contacting the chemicals directly. “This means that licking and chewing is an instinctive behavior elicited by olfactory stimulation of iridoids,” Miyazaki wrote.
Cats perceive iridoids through their olfactory system. Giving it to them orally had no effect. Kittens don’t respond to it, but develop the behavioral response with maturity.
But as you may have discovered with your own pet, not every cat responds to the heady effects of these herbs. Some 30% to 50% of cats lack the gene that lets them turn on and tune out. Discovering the gene responsible for the feline reaction to catnip and silver vine is the next goal for Miyazaki and his team.
“Our future studies promise to answer the key remaining questions of why this response is limited to felidae (cat) species, and why some cats don’t respond to these plants,” he says.
Q&A
Pets don’t have
to live in fear
Q: My dog hates getting his nails trimmed. He quivers and quakes whenever I bring out the nail trimmers, and I’ve never even quicked him. Do you have any advice to help with his fear?
A: Pets can be fearful of many things -- loud noises, car rides and, yes, nail trims. People are often unsure how to deal with these fears, and sometimes they default to punishment simply because they’re frustrated. That makes matters worse, but here are some tips to help turn fear around.
When a dog or cat isn’t comfortable being handled -- whether it’s to have nails trimmed, teeth looked at or an exam at the veterinary clinic -- they can respond with the body language you describe, plus panting, lip licking, drooling, and even with a growl or bite. Nobody wants that, including the dog.
That’s when you need to seek out a savvy behavior professional who can help you develop and implement a program of what’s called counterconditioning -- pairing the scary event in small bites (so to speak) with something the animal likes, such as a tasty treat, praise or a favorite toy. The idea isn’t to reward the fear, but rather to change the way the dog or cat experiences the frightening situation.
It’s a slow but steady introduction to the nail clippers and having the nails trimmed. You might do only one a day, followed by some warm deli turkey or whatever your pet’s favorite treat or toy is. Always keep things below the level at which your pet starts showing signs of anxiety.
In a video on the Fear Free website (bit.ly/3NTSH9J), you can see some ways to help improve your pet’s response to nail trims. If you start before it becomes a crisis, you will likely progress more quickly. -- Dr. Marty Becker and Mikkel Becker
Do you have a pet question? Send it to askpetconnection@gmail.com or visit Facebook.com/DrMartyBecker.
THE BUZZ
Summer safety tips
for dogs and cats
-- With warmer weather here, snakes are coming out of brumation -- a period of partial dormancy -- and seeking warmth and prey. It’s all too easy for an unsuspecting or curious dog to get a bite from a startled snake, so pay attention to your surroundings and your dog’s activity when you’re hiking in areas where snakes are found. Depending on where you live, that can be forests, deserts, swamps or grasslands -- or even your backyard. Snakes can be in burrows, under rocks or in water. You might not see your dog get bitten, so be aware of signs such as swelling, pain, difficulty breathing and unexplained salivation, says Steven Marks, DVM, associate dean and director of North Carolina State University’s Veterinary Medical Services. If you see or suspect a snake bite, keep your dog calm and get him to the veterinarian right away. Don’t apply ice or a bandage or tourniquet, and don’t try to suck out venom, Dr. Marks says.
-- In hot weather, be sure your dog or cat always has fresh water and a cool place to rest, especially if you don’t have air conditioning or you have a pet with a flat face, such as a bulldog, pug or Persian cat. Extreme temperatures can cause pets to suffer heatstroke and dehydration. Signs include panting, difficulty breathing, dark red gums, lethargy and high body temperature (104 degrees Fahrenheit or more). Pets with these signs should see the vet immediately. To help pets chill, offer a frozen towel or bag of frozen veggies they can snuggle with.
-- Light-colored or white pets need protection from the sun. Look for pet-safe sunscreen and apply it to the face, ears and nose, or even the whole body in the case of shorthaired or smooth-coated dogs. Keep hairless pets indoors when it’s sunny out. -- Dr. Marty Becker, Kim Campbell Thornton and Mikkel Becker
ABOUT PET CONNECTION
Pet Connection is produced by a team of pet care experts. Veterinarian Dr. Marty Becker is founder of the Fear Free organization, co-founder of VetScoop.com and author of many best-selling pet care books. Kim Campbell Thornton is an award-winning journalist and author who has been writing about animals since 1985. Mikkel Becker is a behavior consultant and lead animal trainer for Fear Free Pets. Dr. Becker can be found at Facebook.com/DrMartyBecker or on Twitter at DrMartyBecker. Kim Campbell Thornton is at Facebook.com/Kim.CampbellThornton and on Twitter at kkcthornton. Mikkel Becker is at Facebook.com/MikkelBecker and on Twitter at MikkelBecker.