7 Unusual Things That Dogs Can Detect by Smell

Dogs have been trained to sniff out the new coronavirus.
Dogs have been trained to sniff out the new coronavirus.
humonia/iStock va Getty Images

Dogs have an extraordinary sense of smell—at least 10,000 times as acute as ours. While humans boast 6 million olfactory receptors, dogs are blessed with up to 300 million. It's no wonder they're being trained to detect a wide range of objects by smell, from bombs to viruses to fertile cows. Dogs are proving themselves more than our best friends—they are also astoundingly precise odor hunters. Here are seven unusual items they've been taught to sniff out.

1. The Novel Coronavirus

Viruses have specific odors, and scientists have discovered that dogs can detect them. Dogs have been able to distinguish between three types of bovine viruses, for example—those causing diarrhea, herpes, and influenza. Now, dogs are being taught to smell viruses that affect humans. Cindy Otto, director of the University of Pennsylvania's Working Dog Center, is training eight Labrador retrievers to sniff out SARS-CoV-2, the coronavirus responsible for COVID-19. If the pilot study works, canine surveillance teams may one day help screen travelers at airports, patients at hospitals, or attendees at conferences.

Dogs that have already been trained to detect malaria are being put to a similar test at the London School of Hygiene & Tropical Medicine. Scientists have collected viral samples to train the dogs, and if all goes well, the UK's government hopes to deploy six dogs to screen travelers from abroad at airports.

2. Bronze-Age Human Remains

Cadaver dogs, or human-detection dogs, can sniff out the scent of decomposing remains in decades-old cold cases. But could dogs’ noses track odors that go back thousands of years? In 2015, Croatian archaeologist Vedrana Glavaš and dog trainer Andrea Pintar decided to test dogs on Croatia’s Velebit mountain range, where Glavaš had uncovered portions of a 3000-year-old hill fort and necropolis. According to their 2018 study in the Journal of Archaeological Method and Theory, the cadaver dogs found graves with burial chests and human finger and toe bones. The dogs, the paper contends, are searching for the molecules of human decomposition. Glavaš believes the rocky, porous karst landscape of the area preserves those molecules well, perhaps better than plain soil.

3. Fertile Cows

Knowing when a cow is fertile—or in estrus—is important to dairy farmers so they can choose the best time for artificial insemination. In the past, farmers tried to determine estrus by observing changes in cows’ behavior, such as mounting or standing to be mounted. Dogs that have been trained to identify odors specific to estrus might be a more accurate way. Dogs can pick up such scents in vaginal fluid, milk, urine, or blood samples with an accuracy of more than 80 percent overall, and in the case of milk, 99 percent. In one 2013 study, 13 dogs, eight of which had previously been trained to detect narcotics or cancer, were taught to detect estrus-specific scents in cow saliva. They were able to pinpoint estrus in nearly 60 percent of the samples.

4. People Carrying Explosives

Though we can’t see them, we all trail thermal “plumes” in our wake as we move through air—and dogs have been trained to detect them for traces of explosives. In Auburn University's Canine Performance Sciences program, researchers have taught Labrador retrievers to detect body-worn explosives in crowds, including at large concerts and airports, by following scent particles in human heat plumes. This patented method, dubbed Vapor Wake, has been used to train dogs for law enforcement agencies and for mass transit organizations.

5. Invasive Pythons

A dog detects invasive snakes as part of the USDA's Animal Plant Health and Inspection Service.U.S. Department of Agriculture, Wikimedia Commons // CC BY 2.0

Auburn University’s detection dogs have also been trained to smell Burmese pythons [PDF] slithering through Florida's Everglades National Park. Thousands of the pythons, an invasive species, hide in the Everglades’ tall grasses and prey on native mammals and birds. In 2010, two dogs named Ivy and Jake found 19 snakes in the park, and in 2017, dogs named Floyd and Vito sniffed out five pythons on North Key Largo in the Florida Keys. The python-sniffing pups were trained as part of Auburn's Eco Dogs program.

6. Bed Bugs

When bed bugs invade homes, they hide in crevices and cracks and can be very hard to get rid of. One reason is because they're difficult to see, but dogs—who hunt by smell—have proven to be good detectives. In 2008, researchers at the University of Florida trained dogs to discern the odor of bed bugs and their eggs from those of other insects with 97.5 percent accuracy. The dogs were able to smell the difference between live bed bugs or eggs and dead bed bugs, their skins, and their feces. But in the real world, bed bug-detecting dogs sometimes they detect bugs where there are none, wasting consumers' time and money.

7. Cancer

In 2013, a 75-year-old man visited his doctor after his dog kept licking at a small lesion behind the man’s ear. The lesion turned out to be a malignant melanoma—and it wasn’t the first case in which a dog had sniffed out cancer in humans. Different cancer types have specific odor signatures. Some researchers suggest that detecting cancer by that signature, potentially before a visible tumor forms, may catch cancer at earlier stages and prolong survival. The Penn Working Dog Center's cancer detection program is training dogs to imprint on tissue and blood samples donated from ovarian cancer patients. The researchers hope to isolate the odor the dogs identify and develop an electronic sensor that will screen cancers earlier.

Amazon's Under-the-Radar Coupon Page Features Deals on Home Goods, Electronics, and Groceries

Stock Catalog, Flickr // CC BY 2.0
Stock Catalog, Flickr // CC BY 2.0

This article contains affiliate links to products selected by our editors. Mental Floss may receive a commission for purchases made through these links.

Now that Prime Day is over, and with Black Friday and Cyber Monday still a few weeks away, online deals may seem harder to come by. And while it can be a hassle to scour the internet for promo codes, buy-one-get-one deals, and flash sales, Amazon actually has an extensive coupon page you might not know about that features deals to look through every day.

As pointed out by People, the coupon page breaks deals down by categories, like electronics, home & kitchen, and groceries (the coupons even work with SNAP benefits). Since most of the deals revolve around the essentials, it's easy to stock up on items like Cottonelle toilet paper, Tide Pods, Cascade dishwasher detergent, and a 50 pack of surgical masks whenever you're running low.

But the low prices don't just stop at necessities. If you’re looking for the best deal on headphones, all you have to do is go to the electronics coupon page and it will bring up a deal on these COWIN E7 PRO noise-canceling headphones, which are now $80, thanks to a $10 coupon you could have missed.

Alternatively, if you are looking for deals on specific brands, you can search for their coupons from the page. So if you've had your eye on the Homall S-Racer gaming chair, you’ll find there's currently a coupon that saves you 5 percent, thanks to a simple search.

To discover all the deals you have been missing out on, head over to the Amazon Coupons page.

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Treat Your Feline This Holiday Season With Fancy Feast’s Cat Food Advent Calendar

Fancy Feast/Chewy
Fancy Feast/Chewy

In anticipation of the holiday season, many children and adults get to unwrap mini presents each of the 24 days leading up to Christmas day, during what's known as Advent. Though Advent itself dates back to the 4th century, the version we know today, complete with the chocolate-filled calendars, was popularized in the early 1900s. And apparently it's no longer just for humans, because Fancy Feast is letting your feline roommate in on the fun with this unique cat food Advent calendar, now available at Chewy for $23.

For the 24 days leading up to Christmas, your cat will get to enjoy a variety of different wet foods, including favorites like grilled salmon, chicken, and more. There is even a unique ornament included with each calendar featuring a cat in the shape of a heart that can go right onto your tree. (Also, don't be surprised to find your actual cat making its way into the middle of your tree; they're known climbers.)

Now while you enjoy your Advent calendars from brands like LEGO, Funko, and more, your cat will be able to join in on the fun as well. To learn more about Fancy Feast's Feastivites Advent Calendar, head on over to Chewy.

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This article contains affiliate links to products selected by our editors. Mental Floss may receive a commission for purchases made through these links.