20 Weird Dog and Cat Behaviors Explained by Science

Let's take a leap into the wild brains of your adorable, and often baffling, four-legged housemates.

It's no mystery that most domestic cats dislike being in water, whether for a bath or a dip in a pool or lake. Most dogs, on the other hand, can't get enough of it. But why is this?

Perhaps it's because a cat's fur takes longer to dry than a dog's does, and cats don't like being sopping wet while they wait to dry off, Kelley Bollen, director of behavior programs for the College of Veterinary Medicine at Cornell University, told Live Science in 2010.

Or maybe cats prefer to have all four feet on a solid surface and "do not appreciate the sensation of floating in the water," she said.

Moreover, some dog breeds, including the Portuguese water dog and the Irish water spaniel, are bred to "work" in the water and have body types equipped for swimming.

In addition, most dogs are pleasantly introduced to water when they're young, while cats are not, Suzanne Hetts, a wildlife biologist with Animal Behavior Associates in Colorado, told Live Science. 

Cats like to stretch largely for the same reasons people do: It feels good, and it increases blood flow to the muscles, Andrew Cuff, a postdoctoral researcher of anatomy at the Royal Veterinary College in London, told Live Science in April 2016.

Cats sleep between 12 and 16 hours a day, meaning they're not moving for long amounts of time. When cats are sitting still or sleeping, their blood pressure drops, Cuff said. Stretching can reverse that, he added.

"As you stretch, it activates all of your muscles and increases your blood pressure, which increases the amount of blood flowing to the muscles and also to the brain," Cuff said. "This helps wake you up and make you more alert."

Stretching can also flush out toxins and waste byproducts that build up in the body during periods of inactivity, Cuff said. Moreover, when a cat stretches, it readies its muscles for activity, such as running after a mouse … or a treat.

Dogs often walk in circles before settling down for a snooze. This curious behavior is actually hardwired in them from prehistoric times, Leslie Irvine, author of "If You Tame Me: Understanding Our Connection With Animals" (Temple University Press, 2004), told Live Science in 2011.

Fido's wild dog ancestors would walk in circles to make a nest — an area with stomped-down grass or underbrush where they could sleep. This behavior may have also driven out snakes or large insects that otherwise might have bothered them, Irvine said.

Moreover, a nest would mark the dog's territory, telling other dogs to stay away, she said. 

Dogs aren't just particular about their cozy "nests." Turns out, some pups like to poop while they are aligned with the north-south axis of the Earth's magnetic field. To come to this wacky conclusion, researchers spent two years observing 70 dogs as they defecated and urinated.

The dogs studied, which included 57 different breeds, tended to face north or south while pooping and seemed to avoid facing east or west, the researchers noted in their study, published in 2014 in the journal Frontiers in Zoology. Even so, the researchers are not sure how the dogs are sensing the magnetic field (if they are, in fact, sensing it) or why they'd have such a particular pooping position. 

Speaking of poop … Why do domesticated cats bury their poop, spraying litter across the floor as they finish the deed?

Scientists suggest this poop-burying practice is tied to submission and precautionary measures. In the wild, predators with sensitive noses can likely easily pick up the smell of cats' urine and feces, according to Animal Planet. So, smaller and weaker cats that are more submissive may bury their poop to keep from riling up more dominant animals, Animal Planet said.

In contrast, big, dominant cats in the wild, such as lions and tigers, sometimes mark their territory with excrement but do not bury it, according to Mental Floss.

Some may even bury their poop because they see themselves as subordinate to their human owners, zoologist and ethologist Desmond Morris wrote in his book "Catlore" (Crown Publishers, 1988). 

Even though most pet cats have access to a bowl of kibble, these natural-born hunters often still bring home mice, birds and other small animals they've killed during their outdoor escapades.

That's because wild cats usually eat several small meals a day, and that instinct didn't disappear when they were domesticated about 10,000 years ago. Moreover, mother cats in the wild catch prey and bring it home to teach their young how to eat. Domestic cats are often spayed, meaning they can't have kittens. But they may still try to pass on their hunting wisdom.

In fact, your cat may think you're a "kitten" that needs feeding or may want to thank you for the food you provide her, according to veterinarian Dr. Marty Becker on VetStreet.com.

It's best to keep that chocolate bar out of Fido's reach. Chocolate contains theobromine and caffeine — stimulants that are dangerous to dogs, Greg Nelson, senior vice president of Central Veterinary Associates in Valley Stream, New York, told Live Science in 2011.

After a dog eats chocolate, it might begin to drool excessively, vomit and have diarrhea. These are signs that the chocolate is toxic to the dog, Nelson said. Dogs can also experience an increased heart rate and act restless, nervous or excited because of the caffeine, he said.

In addition, an irregular heart rate can cause poor circulation, which can lead to a drop in body temperature. If the dog has an extreme reaction, it could have lethargy, muscle spasms and/or seizures; go into a coma; or even die, Nelson said.

If your dog has ingested chocolate, call your veterinarian for advice. You should also call your vet if your dog eats a grape or raisin, as these can cause kidney failure in certain breeds.  [Are Grapes Toxic for Dogs?]

Anyone who has a cat knows that as soon as a box enters your home, your cat will turn it into a home in no time. But why do they seek out these confined spaces?

This behavior is likely instinctual; in the wild, enclosed spaces can help cats hide from predators and stalk prey.

"Cats like boxes because they are cryptic animals; they like to hide," Stephen Zawistowski, science adviser for the American Society for the Prevention of Cruelty to Animals, told Business Insider. "And a box gives them a place of safety and security."

A box can also help cats see what's coming at them, essentially helping them scan the area without being seen, Zawistowski said. What's more, if the kitty leaves the box to chase prey or a toy, it can always return to its safe zone afterward. [Why Do Cats Like Boxes?]

Dogs sweat, but not like people do.

When people sweat, they rely on their vast number of eccrine sweat glands all over their bodies. The sweat wets the skin and then evaporates, cooling the body in the process, Yana Kamberov, an assistant professor of genetics at the University of Pennsylvania, told Live Science in October 2016. This system allows people to continue walking, trekking or running without overheating, she said.

In contrast, dogs have sweat glands only on their paws and noses, Catherine Carrier, a veterinarian and animal operations senior manager at Covance Laboratories, a contract research facility that partners with pharmaceutical companies, told Live Science in July 2016. It's possible that sweaty paws give dogs more traction, Carrier said.

But sweaty paws aren't enough to cool off a dog. Rather, dogs mostly cool off by panting, Carrier said. [Do Dogs Sweat?] 

Dogs have some of the animal kingdom's most sophisticated and skilled noses. In fact, their sense of smell is 10,000 to 100,000 more acute than humans', according to an article on NOVA. That super sniffer leads to perhaps the ultimate, albeit stinky, dog mystery: What's up with all that dog-on-dog butt sniffing?

Those tail-wagging maniacs are communicating, of course. Or that's what scientists think, though there is a dearth of research to confirm that they are spreading information with their butts. What scientists do know is that dogs have anal sacs that secrete smelly, volatile compounds. For instance, George Preti, now at the Monell Chemical Senses Center in Philadelphia, found that the sacs emit a cocktail chock-full of trimethylamine, and several short chain acids such as propionic acid and butyric acid. His study was detailed in 1976 in the Journal of Chemical Ecology.

What those chemicals are telling other dogs is a mystery, said Anneke Lisberg, an associate professor of biological sciences at the University of Wisconsin Whitewater who studies chemical communication signals in domestic dogs. One study by Cheryl Asa, of the University of Minnesota, and colleagues found that wolves showed some particularities related to anal secretions: Adult male wolves, especially the alpha males, released anal-sac chemicals while pooping more frequently than females or juvenile wolves, the scientists wrote in 1985 in the Journal of Mammalogy.

Sometimes, wolves would deposit these butt scents without pooping, "suggesting a dual role in communication by these substances," the researchers wrote. As for what types of dogs seem to prefer butt-sniffing behaviors, one study found that, at least in dog parks, male dogs were more likely than females to sniff another dog's butt, while females were more likely to inspect the other canine's head, according to the study, published in 1992 in the Journal of the International Society for Anthrozoology.

You knew it was coming… Your dog doesn't only smell other dogs' bottoms and poop in odd ways — Fido also sometimes consumes feces. This behavior, called coprophagia, sometimes happens because the dog has a health condition, such as diabetes or Cushing's syndrome, that alters its appetite. Other times, it's due to nutrient deficiencies, according to VCA Animal Hospitals.

But oftentimes, perfectly healthy dogs will eat poop. It's unclear why, but one hypothesis is that coprophagia is simply a scavenging behavior, a remnant of dogs' evolutionary history.

Another idea is that dogs learn this behavior during puppyhood, when their mothers lick their genitals to stimulate urination and defecation, and then eat the excrement to maintain a clean den. It's also possible that dogs eat poop simply because they're bored. [Why Do Dogs Eat Poop?]

Regardless of the reason, eating feces can be harmful, as one case report revealed: A 1-year-old female mixed-breed dog was brought to the vet because of urinary incontinence, abnormal thirstiness and an excess of diluted urine, according to the report, published in 2013 in the Journal of the American Veterinary Medical Association. Turns out, the young pup had eaten the feces of another household dog, and that dog was being treated with a nonsteroidal anti-inflammatory drug called carprofen. The drug ended up in the treated dog's feces and then was transferred to the female when she ate that poop. 

Science doesn't have a clear answer on this one, so cat and dog lovers may forever debate whether Fluffy or Fido is brainier. But there are hints as to which fluff ball is most intelligent.

Cats' brains take up 0.9 percent of their body mass, compared with 1.2 percent for a dog's brain, but size doesn't necessarily matter here, experts say. That's because cats have 300 million neurons in their cerebral cortex, an area of the brain responsible for information processing. Dogs have 160 million neurons in that region.

However, it's hard to do experiments with cats because, well, they'd rather lick their paws than follow orders, scientists say. But one experiment showed that although both cats and dogs can solve puzzles to get food, cats will keep trying even if the puzzle is unsolvable, while dogs will go get humans to help them.

This doesn't mean either animal is smarter. It just shows the effects of how dogs were domesticated at least 20,000 years before cats were, and thus are more likely to interact with humans, the study researchers said. [Are Cats Smarter Than Dogs?]

Is it true that your household canine wags his tail out of glee? Sort of. Dogs do wag their tails as a form of communication, research has found. But a little shimmy doesn't always say, "Come pet me." Perhaps surprisingly, in 2007, researchers found that whether the tail is swishing on the right or left side of the dog's body has meaning: A tail wag that's skewed toward the right indicates positive emotions, while a leftie wag suggests negative emotions.

The left-right difference may be linked to the differences found in the right and left hemispheres of a dog's brain, the researchers noted. In addition, research published in 2013 in the journal Current Biology revealed that a right-wagging tail tends to relax canine passersby, while a left wag seems to stress out other dogs. 

The position of a dog's tail, even when it's not wagging, can also convey meaning. A tail held high above the spine may indicate arousal, while a tail tucked between the dog's rear legs can suggest fear, according to the American Society for the Prevention of Cruelty to Animals.

Zooming around in circles in hot pursuit of a furry thing that seems just a hair out of reach … Yes, tail chasing can be a pastime for some dogs. So, why do they do it? The dizzying behavior may be a throwback to your canine's hunting days; even if your dog isn't living in the wild, he or she has kept survival instincts, so when a moving tail comes into the dog's view, it's off to the races, according to the Canine Journal. Of course, that's not the only reason for running round and round — your dog could be chasing an itch if he or she has fleas or ticks, according to the journal.

If the tail-chasing behavior becomes excessive, it could be a sign of the doggy version of OCD, called canine compulsive disorder, according to a study published in 2012 in the open-access journal PLOS ONE. That study found that dogs given dietary supplements such as vitamins and minerals were less likely to show the excessive tail-chasing behaviors. Overall, the dogs with tail-chasing issues were shier and had been separated from their moms earlier than those without the compulsive behavior.

Turns out, your cat is not making biscuits when he or she seems to be kneading your pillow. That said, scientists aren't sure exactly why cats "knead," though they have some hypotheses. The most common explanation is that it's a leftover behavior from kittenhood, when the little fur ball would knead around its mom's teats to stimulate milk flow, according to a review of research published in the Journal of Veterinary Behavior in 2016. The behavior might also date back even further, to Fluffy's wild ancestors that apparently would pat down the foliage to make a soft bed or spot for giving birth. And still another idea is that kneading is one way of stretching for your cat (and cats love to stretch after a long nap), according to PetMD. 

When your cat turns her nose up at the food you place in front of her, don't feel bad. First of all, you're not alone — cats around the world are picky eaters. In fact, the seemingly snobby behavior may be hardwired into a feline's brain.

And rather than judging food on its smell, taste and feel, cats may be doing some math, albeit instinctually, in their heads. That's because they need foods with a 1 to 0.4 ratio of protein to fat, according to a study published in June 2016 in the journal Royal Society Open Science. "Given that the foods contained negligible energy from carbohydrate, this would equate to approximately 50 percent of total daily energy intake from protein and 50 percent from fat," the researchers wrote in the paper. How your cat can detect this nutrient ratio remains a mystery … for now.

If you're a cat owner, you've probably seen your wild fur ball take some pretty fantastic spills while walking across a narrow or shaky surface. Every time, the confidant beast nails the landing.

Here's why: For one, they're built for leaping, as they have an exceptional sense of balance and extra-flexible backbones because they have more vertebrae than humans. The extra vertebrae let them twist their bodies in midair and right themselves while falling. This aerial righting reflex has been described not only in cats but also in various other mammals, such as guinea pigs, rabbits, rats and primates, researchers wrote in 2011 in the journal Integrative and Comparative Biology. By 3 weeks old, kittens have mastered this righting reflex, according to a study published in 1984 in the journal Experimental Neurology.

This ability, however, doesn't give cats superhero status, and falls from heights can lead to injuries. In fact, high-rise syndrome — when cats fall from a height of more than two stories — can lead to fractured limbs and chest and other injuries, according to a study published in 2004 in the Journal of Feline Medicine and Surgery.

Most cat owners are quite familiar with a behavior that Pam Johnson-Bennett, author of several cat books, called the "elevator butt," in which your cat raises her hindquarters while lowering the front part of her body. Usually, the silly-looking posture occurs when you're petting a cat.

"Although elevator butt may seem rather insulting to us, it's actually the cat's very positive response to the fact that you've hit just the right spot when petting her," she wrote in her book "CatWise: America's Favorite Cat Expert Answers Your Cat Behavior Questions" (Penguin Books, 2016). Where is that sweet spot? Just at the base of the tail, though not all cats enjoy being rubbed there, Johnson-Bennett said.

But that elevator-butt stance, also called lordosis, has a sexual meaning as well. A female cat that hasn't been spayed may raise her posterior area to signal to males that she's ready to mate, Johnson-Bennett wrote.

When dogs snuggle in for some shut-eye, they sometimes enter the dream world. Turns out, in this respect, your dog is a lot like you: When they drift off, dogs cycle through stages of wakefulness, rapid-eye-movement (REM) sleep and non-REM sleep, according to research published in 1977 in the journal Physiology & Behavior. In that study, scientists recorded activity in the brains of six pointer dogs. They found that the canines spent 12 percent of their time in REM sleep and 23 percent of their time in the deepest stage of non-REM sleep, called slow-wave sleep. For people, the most memorable dreams occur during REM sleep.

Though researchers suspect your dog does have dreams, what makes up those dreams is an area of ongoing research. One way for scientists to enter a dog's dream world is to temporarily block the muscle-paralyzing part of the brain's pons, a region in the upper part of the brainstem; when that happens, dogs start to act out their dreams.

"What we've basically found is that dogs dream doggy things," Stanley Coren, a professor emeritus of psychology at the University of British Columbia and the author of "Do Dogs Dream? Nearly Everything Your Dog Wants You to Know" (W. W. & Norton Co., 2012). "So, pointers will point at dream birds, and Dobermans will chase dream burglars. The dream pattern in dogs seems to be very similar to the dream pattern in humans," Coren told Live Science in February 2016. Coren also found that tiny dogs likely have shorter, but more frequent, dreams than larger dogs.  

When your kitty pushes his or her head up against you repeatedly (as they seem to do everything), they are indicating that you're a part of their group, according to PetMD. Just like cheek-rubbing behaviors, in which a cat rubs her face against a human's skin, head "bunting" is another way of spreading their scents. According to PetMD, cats have scent glands in the spot on their heads above the eyes but below the ears — exactly where they push into you. By releasing its own scent, your fickle feline is bonding with you,  Johnson-Bennett said on her website Cat Behavior Associates.

"The bunting and rubbing are reserved for bonding, social, comforting and friendly purposes," Johnson-Bennett wrote. "When your cat engages in head bunting or head rubbing, he is placing his scent there as a social and affectionate gesture."