You run just the right amount of water at the perfect temperature while trying to convince your dog how good he’ll feel after his bath. The doggy shampoo you squirt over his coat has a pleasant smell, and your four legged friend is satisfied munching on CANIDAE treats while you scrub him from head to toe. A question arises, however, while drying off your pet – why doesn’t he smell as good as the shampoo you smeared all over him? Dogs definitely do have a unique wet dog smell, and there is science that can explain what causes it, which begins the minute water hits your dog’s skin.
Dogs may have a better nose than humans, but our nose is also pretty amazing. Microscopic molecules in the air enter the nose when we inhale, finding their way to specialized cells called olfactory sensory neurons located in the nasal cavity. The job of these cells is to recognize the chemical makeup of molecules and send the information to the brain via electrical signals where it’s decoded into a recognizable smell – a steak sizzling on a grill, the scent of a flower… or the smell of a wet dog.
Dogs and humans share three senses—hearing, smelling and seeing—but we rely on them in different ways, or rather, with different levels of dependence. For the majority of humans, hearing is their primary sense followed by seeing and lastly, smelling. There are some humans who are more visually focused and take in and process visual information before auditory information but as a general rule, the order of sensory dependence is hearing, seeing and then smelling.
A dog, on the other hand, primarily relies on his sense of smell. For our canine friends, the order of sensory dependence is smelling, seeing and then hearing. Amazingly, our dogs receive and understand as much information via smelling as we do via sight!
A dog’s reliance on the nose starts at a young age. When puppies are born, their eyes are closed and their ears are stopped up. Even so, they are born with heat sensors in their noses which help them locate their mother in order to nurse. These heat sensors fade with time, and fully adult dogs no longer have this ability.
The paws are not usually the first thing we notice when looking at a dog. Some canines have wide paws while others have more slender feet, and some have webbing between their toes. Over the centuries, the anatomy of dog paws adapted to the environment the dogs lived and worked in, to make it possible for them to do the jobs they were bred to do. Here are some amazing facts about dog paws you may not know.
A dog’s paw consists of five parts:
1. The claws, which give dogs a good grip on a surface
2. Digital pads, directly under the toes
3. The metacarpal pad, directly under the digital pads
4. The dewclaw
5. The carpal pad located on the front paws at the back of the foot
My dogs know before I put them outside if there is an animal near their dog pen, even in the winter with the windows down. By the time they get outside, they’ve already pinpointed the area where a cat, possum or other small animal is. A dog’s nose is amazing. Everything about a dog’s nose is designed to give him a sort of “super power” when it comes to smelling. Even the slits on each side of their nose have a specific function.
Every time a dog breathes, he pulls in smells. The canine sense of smell is 10,000 to 100,000 times better than ours. James Walker, former director of the Florida State University Sensory Research Institute, came up with a good visual to explain the difference between our sense of smell compared to a dog. “If you make the analogy to vision, what you and I can see at a third of a mile, a dog could see more than 3,000 miles away and still see as well,” he said.
Another way to grasp the power of a dog’s nose is to imagine two million barrels of apples sitting in a warehouse. A dog could walk in and detect the one rotten apple hiding among all the others. Once a dog has been trained to detect a specific scent, such as drugs, bedbugs, cancer or low blood sugar, he can find it regardless of other scents around him. One reason why canines can isolate a scent is due to the slits on each side of their nose.
Compared to our ability to distinguish between 4,000-10,000 different smells, dogs can process 30,000-100,000 scents. Because they use scent more than the other senses to navigate through their world, the amount of brain power devoted to their sense of smell is 40 times greater than ours. As a dog inhales, the air is separated and splits into two different paths. One path takes about 12% of air to the back of the nose for scent analysis, and the rest passes through that area and goes to the lungs.
The air that stays at the back of the nose is filtered through a maze of ruffle-like bony structures called turbinates that sift out odor molecules according to their chemical makeup. Olfactory receptors in the tissue of the turbinates then recognize an odor based on their shape, and send impulses to the brain to process.
The slits on each side of the nose give dogs the ability to have a constant stream of air that can span many respiratory cycles. When we inhale and exhale, the air goes out the same way it came in and any odors that entered are forced out along with the air. In dogs, exhaled air goes out through the slits and the swirling motion of air helps new odors enter the nose. This makes it possible for a dog searching for smells to have a steady stream of air coming in for up to 40 seconds, and maybe even longer.
The slits also allow dogs to wiggle each nostril independently, and give them the ability to know which nostril a smell entered. This is how a dog can pinpoint where a smell is coming from, and why a canine searching for smells on the ground will weave back and forth as he follows a trail.
At the bottom of the canine throat is a second structure found in cats and other mammals: the Jacobson’s organ, which is used to pick up pheromones. The smells it detects are sent to a part of the brain that’s devoted to only analyzing the pheromone molecules it picks up. It lets dogs smell and taste the scent. If you’ve ever seen your dog sniffing with his mouth open in a sort of grin, he’s having a Flehman Reaction and catching a whiff of a female in heat or sniffing urine left by another dog.
Once a dog has learned a scent, he can remember it for a long time. Certain dog breeds like the Bloodhound and Basset Hound have some added features that increase their scenting ability. Their long ears help sweep up smells from the ground, and loose skin around the chin traps scents.
The slits in a dog’s nose enhance their sniffing ability so they can follow prey, locate someone lost in the woods or buried under snow, and root out their CANIDAE treats no matter where you hide them. When you see your dog with his wiggling nose in the wind, you can bet he’s savoring every bit of information that’s riding in the breeze. That’s a pretty remarkable feat when you think about it!
Like cats and other animals, dogs have whiskers that stick out from the sides of their muzzle. Technically, they aren’t whiskers – they’re called vibrissae, which comes from a Latin word “vibrio” that means to vibrate. A dog’s whiskers are actually highly tuned, multi-functional, sensitive sensory hairs they need and use every day to perform specific functions that help them move around in their world.
Dog whiskers are found on both sides of their muzzle, as well as on the forehead above the eyes, on their chin and above the upper lip. As puppies grow, the whiskers are among the first hairs to develop. Unlike the neatly arranged 12 whiskers in four rows on each side of a cat’s face, dog whiskers are more varied in their pattern depending on their breed and genetics.
Whiskers are twice as thick and coarser than regular dog hair. Their roots are set three times deeper and packed with nerves and blood vessels that make each individual whisker a super sensitive receptor to movement. Air moving it or objects brushing against it causes the whisker to vibrate and stimulates the nerves. Dog whiskers are as sensitive as our fingertips. Whiskers play an important role in helping dogs understand and move through their environment.
Regardless of how human and canine paths came together, the history we share is unique and special. Early dogs weren’t the cuddly, family-friendly pets we cherish today, and domestication was likely initiated by the animal and not by man. The history of dogs is filled with fascinating facts.
Dogs, wolves, coyotes, dingoes, jackals and foxes are members of the Canis Family. (Canis comes from the Greek word kūon and means “dog”). These animals are opportunistic, adaptable, intelligent and found in every habitat on Earth. Their early history goes back to around 65 million years ago to a carnivore that resembled a weasel, the Miacis (My-ah-sis) that made its home in trees and dens in Europe, China and North America. These creatures evolved into the Tomarctus (Toe-mark-tus), a hyena-like animal that lived about 15 million years ago and lived throughout North America. These animals are thought to be direct ancestors of the Canis Family – prehistoric dogs.
The Tomarctus had five toes on their back feet, but as it evolved into Canids, the fifth toe became immature, and the remnants of the fifth toe are seen in the dew claws found on the back feet of wolves and some dog breeds.
One of the first Canids, the dawn-wolf, looked like a fox with an elongated body. This creature was as cat-like as he was dog-like, living in and climbing through trees. It’s believed this animal could be related to the feline species as well as to Canids.
Because the domestication process happened so long ago, and archaeological findings have provided small clues, scientists are divided on the evolution of wolves. They are equally divided on the origin of where wolves first lived. One theory says Canids began in North America before spreading out to areas in South America and Asia.
It’s possible the grey wolf had a smaller ancestor that crossed the Bering Strait land bridge to Siberia where it evolved before making its way back to Canada and the United States as the wolf we know today. And a third theory suggests Canids began in North America, found their way to Asia, and then migrated back.
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