Dogs sniff each other’s backsides as a way of gathering important information about each other. This behavior is rooted in their natural instincts and is a form of communication.

The area around a dog’s anus contains scent glands that produce pheromones, which provide a wealth of information about the dog’s identity, health, age, sex, and even their emotional state

. By sniffing, dogs can learn a lot about one another, which helps them understand social hierarchy, find potential mates, and avoid conflicts. It’s a completely normal and natural behavior for dogs!

Last Updated on January 2, 2025 by News Time

Dogs can smell when people are stressed, and it seems to make them feel downhearted.

Humans and dogs have been close companions for around 30,000 years, based on anthropological and DNA evidence. This long history suggests dogs are particularly attuned to interpreting human emotions. They have evolved to read verbal and visual cues from their owners, and previous studies have shown that their acute sense of smell allows them to detect stress in human sweat. Now, researchers have found that not only can dogs smell stress—manifested as higher levels of the hormone cortisol—but they also react to it emotionally.

In a new study published Monday in Scientific Reports, scientists from the University of Bristol in England recruited 18 dogs of various breeds, along with their owners. Eleven volunteers, unfamiliar to the dogs, underwent a stress test involving public speaking and arithmetic, while samples of their underarm sweat were collected on cloths for analysis.

Next, the human participants took part in a relaxation exercise, which involved watching a nature video while seated on a beanbag chair under dim lighting. After this, new sweat samples were collected. Sweat samples from three of these volunteers were used in the study.

The participating dogs were divided into three groups and exposed to sweat samples from one of the three volunteers. Before this, the dogs were trained to associate a food bowl at one location with a treat and a bowl at another location with no treat.

During testing, bowls without treats were occasionally placed in one of three “ambiguous” locations. In one session, when the dogs smelled the sweat sample from a stressed volunteer, they were less likely to approach the bowl in the ambiguous location compared to when they smelled a cloth without a sample. This suggested that the dogs believed the bowl did not contain a treat. Previous research indicates that expecting a negative outcome reflects a down mood in dogs.

The results suggest that when dogs are around stressed individuals, they become more pessimistic about uncertain situations. In contrast, being near people with a relaxed odor does not have this effect. This was explained by Zoe Parr-Cortes, the lead study author and a Ph.D. student at Bristol Veterinary School, University of Bristol.

“For thousands of years, dogs have evolved alongside us, learning to live with humans,” says Zoe Parr-Cortes. “Both humans and dogs are social animals, and there’s an emotional contagion between us. Being able to sense stress from another member of the pack would have been beneficial, as it alerted them to a threat that the other member had already detected.”

Katherine A. Houpt, a professor emeritus of behavioral medicine at Cornell University’s College of Veterinary Medicine, explains that the fact the odor came from an unfamiliar individual highlights the importance of smell for dogs and its influence on their emotions in practical situations.

Houpt, who was not involved in the study, suggests that the smell of stress might have reduced the dogs’ hunger, as stress is known to affect appetite. “It might not be changing their decision-making, but rather their motivation for food,” she says. “It makes sense because when you’re super stressed, you’re not as interested in that candy bar.”

This research, Houpt adds, demonstrates that dogs have empathy based on smell, in addition to visual and verbal cues. When you’re stressed, she suggests, it could lead to behaviors in your dog that aren’t typically seen. Moreover, it raises questions about how stress might affect dogs when they’re exposed to the heightened anxiety of their owners.

“If dogs are responding to mild stress like this, I’d be curious to see how they react to more intense situations, such as an impending tornado, losing a job, or failing a test,” Houpt says. “One would expect the dog to be even more attuned to a real threat.”

Last Updated on November 21, 2024 by News Time

“We Now Know the Nerve Behind Dogs Shaking Water on Your Clothes”

“If you’ve ever spent time with a dog, you’ve likely experienced this: you’re lounging by the pool on a hot day, tossing a stick for your furry friend. After fetching it, Fido trots over, flashes a doggy grin, and shakes cold water all over your dry clothes.”

“Scientists have finally uncovered the reason behind the infamous ‘wet dog shake.’ New research reveals that a receptor in mammal skin called C-LTMR is responsible for this behavior. When droplets of liquid land on the back of the neck, it triggers a consistent shaking response in furry animals, from dogs and cats to mice.”

“It’s a complicated behavior,” said Dawei Zhang, co-author of the research and a doctoral student at the Howard Hughes Medical Institute of Harvard Medical School.

The study, published today (Nov. 7) in Science journal, reveals new insights into the “wet dog shake.” According to Zhang, animals across species tend to shake at the same frequency, typically with three back-and-forth shakes, but until now, researchers didn’t know which receptors and nerves were responsible for this behavior.

New genetic tools allowed Zhang and his colleagues to uncover the cause of the “wet dog shake.” The team began by creating genetic mutations in mice to knock out either the channels in skin receptors that detect mechanical forces or the receptors that respond to temperature changes. This approach helped them pinpoint the culprit behind the shaking behavior.

The researchers discovered that mice unable to detect temperature changes still performed the “wet dog shake” when droplets of oil were sprinkled on their necks — the most reliable way to trigger the behavior. However, mice lacking mechanoreceptor channels, which detect mechanical forces, did not shake at all.

Zhang and his team zeroed in on mechanoreceptors, tracking their activity in response to the oil droplets. They identified three receptors that respond to very light touch. Using optogenetics, a technique that activates specific receptors with light, they were able to trigger the individual nerve types without needing any liquid stimulus, further pinpointing the source of the shaking behavior.

The results were conclusive: when the researchers stimulated a type of nerve called C-fiber low-threshold mechanoreceptors (C-LTMRs), the mice shook as though they’d just been sprayed with water. To confirm their findings, they engineered mice without C-LTMRs and discovered that these mice shook 58% less than normal mice when drizzled with water.

C-LTMRs have long been a mystery, Zhang explained. While research conducted 80 years ago suggested they might be responsible for creating ticklish sensations in animals, it wasn’t clear how animals experienced this stimulus. In humans, similar mechanoreceptors called C-mechanoreceptors are linked to pleasurable, brushing sensations on the skin.

Last Updated on November 21, 2024 by News Time