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13 Reasons Behind Your Dog’s Weird Behavior

It's our natural tendency to project our human traits and emotions onto dogs—until you see your dog rolling in the mud. You just can't explain that, but these canine experts can.

DogSigma S/Shutterstock

Why do they “run” in their sleep?

As you may have guessed, this usually means they’re dreaming, and fortunately, it’s not usually of any medical significance, says Gary Richter, DVM, integrative veterinarian, and veterinary health expert at What’s interesting is that studies revealed certain dog breeds acted out their hallmark traits while dreaming, like an English springer spaniel flushing out prey or a pointer “pointing” in its sleep. If all that “running” during sleep seems excessive, Dr. Richter says it could point to underlying stress or a medical condition. Dogs sleeping too much could be a sign of sickness, too—find out how much dogs usually sleep.

Yellow labrador retriever standing on sofa looking out the windowCarol Kelpin/Shutterstock

Why do they bark at the window?

Every day the mail carrier delivers mail, your dog barks. Does this dog behavior simply mean dogs hate mail carriers? “Barking at people outside is a protective behavior. Dogs see their house as their territory and anyone approaching or near their territory is a potential threat, so they bark to ward off the intruder,” says Dr. Richter.  Adding to it, each time the mail carrier delivers mail, your dog barks and the mail carrier goes away. It creates a pattern that is reinforced over and over. “From the dog’s perspective, they are saving the house from invasion every day by driving away the invader. We never appreciate their efforts,” says Dr. Richter. Just like dogs actually have a justification for barking at the mailman, there’s a reason behind each one of your pup’s facial expressions.

Dog rolling over in grass, enjoying sunny day in parkRobert Petrovic/Shutterstock

Why do they roll in stinky things?

Dogs have upwards of 300 million olfactory receptors in their nose, and humans have a paltry six million. With all those receptors, you would think dogs’ high scent orientation would steer them away from vile and pungent smells, like dead animals, yet it’s like Eau de Stinky to them. “Their opinions about what constitutes an attractive scent are often different from ours,” says veterinarian Jennifer L. Summerfield, Brown Veterinary Service, DVM, CPDT-KA. “It’s thought that the behavior of rolling in dead or especially stinky things may have originated as a way of disguising the dog’s scent, which could be useful for hunting.”

Flat Coated Retriever puppy eats a chicken carcassPhil Stev/Shutterstock

Why do they eat gross things?

Like smell, a dog’s sense of taste is vastly different from ours. We both like a juicy burger, but dogs find a rotting chicken or even vomit quite tasty, too. “Dogs originally evolved as scavengers eating scraps on the periphery of human settlements, and feral dog populations today still manage to survive quite well on less-than-ideal food sources like trash, roadkill, and other unsavory options,” explains Dr. Summerfield. But why don’t they get sick when they eat nasty roadkill or expired food? “A dog’s GI tract can process bacteria and other contaminants that would make a human sick and is often able to extract some nutritional value from ‘gross’ things like poop or vomit.” Your dog’s eating habits could also be indicating a serious medical condition, so it’s important to know why your dog eats non-food items, like dirt.

Dog poops in a meadowDora Zett/Shutterstock

Why do they search for the perfect pooping place?

Dr. Summerfield says there are three possible reasons for this. One theory is they are stamping down the grass for a clean place to poop. The second is they are scanning the area for predators before they go. Lastly, a study found the most interesting reason. “A study done in Europe found that dogs tend to align themselves in a North-South position when they poop,” says Dr. Summerfield. Even more fascinating, dogs rarely relieved themselves along the east-west alignment. Think your dog’s bathroom requirements are strange? You probably never even realized these other unbelievable facts about your dog’s behavior.

Dog sniffing other dog's rear, close-upPhotick/Shutterstock

Why do they sniff your crotch?

You really don’t have to apologize to your new friend when your dog sniffs their crotch—but you will anyway. Dr. Summerfield says the reason why you shouldn’t be embarrassed about this dog behavior is that dogs collect a lot of vital information via their nose and the most concentrated sources of pheromones the crotch or butt area whether you have two legs or four. It doesn’t matter if your human or not. “Although we might find this behavior socially inappropriate, sniffing the anus or genital areas of another dog is a very polite and normal way to say hello in the canine world—much like shaking hands for humans,” says Dr. Summerfield. “So it’s not surprising that when they’re meeting a new human friend, many dogs go straight for the crotch for a good ‘getting to know you’ sniff.” In addition to what your pup learns from sniffing your pheromones, there are at least 13 other secrets your dog knows about you.

Cute barking dog not aggressive on leashalexei_tm/Shutterstock

Why are they aggressive to some dogs and scared of others?

“Many dogs are anxious or uncomfortable about interacting with other dogs—this can be due to genetics, negative past experiences, or a lack of adequate early socialization as a puppy,” says Dr. Summerfield. A dog may lunge forward and bark at another dog to keep it from getting to close; other dogs may hide or cower behind you while some just lay down in an overly submissive posture because they’re fearful or not comfortable with the situation. Dr. Summerfield adds, “It’s not uncommon for a dog to be wary of other dogs, but very friendly towards humans—or vice versa.”

Puppy Jack Russell Terrier licks his mistress. A lovable

Why do dogs lick toes (and other body parts?)

Let’s start with the most licked place: our face. “Licking the face, especially around the mouth, is a normal friendly greeting behavior that dogs often display towards other dogs when saying hello. This is usually seen a submissive gesture—a way of saying, ‘Hi there! I’m no threat to you!'” says Dr. Summerfield. So, it’s perfectly natural for a dog to lick a human face too. As far as feet, fingers, and in between toes: The stronger the smell, the higher the attraction. “This may be due to the higher concentration of scent in these areas, which is also why many dogs are attracted to dirty socks and dirty laundry.” While it may be normal for your dog to lick you, you should definitely consider the scary reason you shouldn’t let a dog lick your face.

French bulldog puppy on the carpetPatryk Kosmider/Shutterstock

Why do dogs scoot on their butt?

The butt scootin’ boogie is kind of comical to watch, but you have to wonder why they do it and what they are leaving behind on your floor. It’s a sure sign of plugged or infected anal glands.”Normally, these sacs express their contents, a very pungent-smelling brown fluid, when the dog defecates. But occasionally, the sacs might become plugged or infected and have a hard time emptying on their own,” says Dr. Summerfield. To relieve the discomfort, they scoot their butt on the floor. “If this happens, your veterinarian can normally resolve the problem by expressing the glands manually.” In addition to your dog scooting on their but, make sure to monitor for these things dogs do to let you know they’re sick.

Golden retriever is digging a hole in sandy soil to hide his toy tennis ball. The dog's legs and toy.Candy299/Shutterstock

Why do they stash things?

Some dogs bury their treasures while others stash them behind a chair or under a stack of pillows on the sofa. Dr. Richter says this is purely instinctual behavior. “They are keeping track of their stuff,” he says. To keep their treasures from being stolen by another animal, they hide it for safekeeping. While this dog behavior is perfectly natural, some breeds known for hunting like hounds and terriers are prone to digging and hiding as the prey they hunt lives underground. Dachshunds, another breed known for stashing, may have a cache of toys and treats nestled in the corner of a dog bed.

Boxer canine looks through screen door while waiting for something.Lori Jaeski/Shutterstock

Why do they bolt as soon as the door is open?

A dog can be dead to the world when it’s sleeping, but when a door opens, it instantly comes to life and sprints to the door to check it out. This dog behavior is similar to ours when we’re surprised at something—we perk right up to see what’s up. But for a dog, there’s a little more to it. “This is an instinctive self-protection behavior. Something has moved suddenly and unexpectedly, and they don’t know what may be coming through the door,” says Dr. Richter. Some dogs take it further and bolt through the door because they want to investigate potential threats and defend their space. Didn’t realize your dog was holding down the fort each time he sprinted to the door? You probably never knew these other secrets your dog would tell you if he could.


Why do they pick up and carry something during a walk?

It could be anything really from a magnolia seed pod to a glove someone dropped. “Dogs use their mouths in much the same way that human children use their hands. Many dogs are naturally curious about the world, and if they find an object interesting, they may want to pick it up, hold it, or carry it for a while,” says Dr. Summerfield. They’re curious just like toddlers, and some breeds are attracted to certain objects like a toddler is to a blankie, especially if the dog is a sporting or retrieving breed.

Close up back view of two small Jack Russell dogs sniffing about in Autumn leaves, showing waggy tailsJenny Summers/Shutterstock

Why is their tail wagging to the left?

Tails can express a wide variety of emotions. A low wagging tail with a wide sweeping arc is a friendly wag, while a high, stiff tail may indicate aggression or arousal. But why do dogs wag their tail to a certain side? “Recent studies on dog body language do suggest that there may be a difference as to how the left- and right-sided tail wags are interpreted by other dogs, and in how the dogs feel when wagging their tails to the left vs. the right,” says Dr. Summerfield. In the study, dogs remained relaxed when they saw images of another dog wagging its tail to the right, but when dogs saw the image of the tail wagging to the left, it stirred up anxiety. More research is needed, but it indeed points to the tail as a key communicator. Now that you know why your pooch is acting a little strange, find out the 19 things your dog actually wants from you.

Lisa Marie Conklin
Lisa Marie Conklin is a Baltimore-based writer who writes regularly about pets and home improvement for Reader's Digest. Her work has also been published in The Healthy, HealthiNation, The Family Handyman, Taste of Home, and, among other outlets. She's also a certified personal trainer and walking coach for a local senior center. Follow her on Instagram @lisamariewrites4food and Twitter @cornish_conklin.

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