What’s in a smell?
The canine nasal airway. (a) Three-dimensional model of the left canine nasal airway, reconstructed from high-resolution MRI scans. (b) The olfactory recess is located in the rear of the nasal cavity and contains scroll-like ethmoturbinates, which are lined with olfactory epithelium. The olfactory (yellowish-brown) and respiratory (pink) regions shown here correspond to the approximate locations of sensory (olfactory) and non-sensory (squamous, transitional and respiratory) epithelium, respectively (Craven et al. 2007).
I open the door to let Aubrey out before bed, she stands there in the doorway body still, lifts her head up slightly her ears drop back her eyes seem to narrow as if in concentration and her little nose is twitching in every direction, I can hear her sniffs, lots of them like chugging train.
I sit beside her wondering what it is she can smell, I take one big sniff in, yet cannot work out what is I am smelling, maybe a fresh scent of the night air, maybe if I close my eyes it will help. One more big sniff in, this time with my eyes closed, I seem to feel instead of noticing any smell, I feel the cold inside my nostrils. A few more deep sniffs in and breaths out I am actually feeling quite relaxed, I feel my shoulders drop. Glancing down to look at Aubrey I notice she is already gone; I hear her in the field running after scent trails with the occasional loud half sneeze after taking into many scent molecules and wanting to clear them out, I am guessing from all those tunnels a mouse has made in the grass.
All I can see is lights from the far away towns, all I can hear is Aubrey running and the cars in the distance on the dual carriageway and all I can smell is now my own hand moisturizer after warming my nose back up!
To think what Aubrey can smell, see, and hear really is mind blowing.
Standing in the doorway she must have seen pictures in the dark, a trail of a fox scent over to the right, A pheasant late to bed visualized by scent alone. The neighbours dogs who went out earlier and every spot that they toileted in and the direction they went in, as scent does mark time the last paw print leaving more odors than the ones in front. I wonder if it was as clear as looking at a picture.
My sister owns a Beagle who has over 300 million receptor sites compared to our mere 6 million!! I do feel sorry for him at times as there must be limited time to rest when faced with an overwhelming selection of smells to digest. Going into a kitchen must be like food heaven or hell as he is not allowed to eat what he can smell, just his bland kibble! You can see the appeal to counter surfing for dogs when they know what's up there. If you own a hound you may notices they sneeze more than other breeds to clear the remaining scent molecules out. Donnie has a little sneezing session quite regularly.
Us humans become used to a smell, we say we become nose blind to it, like me to the inside of my truck! It smells normal to me but every person who sits it in comments straight away about its awful smell (very rude to suggest my dogs and I smell). But dogs do not get nose blind, a scent is always noticeable. They have a part of their nose called a vomeronasal nasal organ which helps. It is a small bone where the sensory cells sits in small chambers, you have seen a male dog obsessed with a spot we all know has a female calling card on it, the male could not push his nose any further into it. It is like he is glued to the spot! While the chemical information he is sniffing up goes straight up to the vomeronasal area, these chemicals are pheromones, they will prompt specific reactions in that males by changing his hormonal levels. Hence why it is ever so tricky getting them to leave it and concentrate after!! And when they do they chatter they teeth together which I wonder is the equivalent to a flehmen response (the lip curl that you'd see in bulls).
We also have this organ. But not as good of course. Thankfully! Its a good job we evolved with a little more decorum. Although is a study somewhere suggesting we can small other peoples pheromones, but ill leave that can of worms for now.
Urine marking is a form of communication, higher the better, get all those pheromones noticed. The sniffer/reader will read sexual readiness and social confidence of the post leaver. It’s not about territorial marking anymore as our dogs aren’t wild... or wolves!!!! It’s all information, how often a dog is there what is his recent activities and even conquests. I’ve entire males who will go back to wee again higher on the same spot and then scrap the floor as much as he can just to establish that he is here more often and ready for action more than the last post marker was! They scratch the floor because they have glands on the paw pads so double whammy of leaving scents. It is always a visual marker of their power and size.
Random interesting fact: Using antibiotics changes a dog’s body odor temporary. Though I would share that, would be interesting to see if your dog was approached differently by a dog it sees regularly.
I think the nose should have a more prestigious title; we cannot compare it to our own. Maybe we should name it the scent vessel?
What happens inside the nose is extremely complicated but here is the simpler Sarah version for you; Muscles in the nostrils draw airflow inside, present air travels deeper inside to get processed or gets pushed out the slits on the side of the nose, this action means airflow and scents gets carried in and get pushed out. The wind generated by the exhale creates a current which helps draw the present odor further in. So, the sniff actually needs a sniff out too, which if you look at your dog’s nose you may notice a little puff of air out. They are continually smelling so no scent goes unnoticed.
Different odorants can be sniffed up each nostril at a time they are then transported and greeted by a vast number of nasal tissues covered in hair to grab and hold each molecule so the receptor sites located in the Cilia of the olfactory epithelium which are all ready to distinguish what information the molecules and chemical have the receptors connect directly to nerves in the olfactory bulbs in the brain so information is learned in an instance.
Of course, we are different species, we never had to rely on our senses to the extent of a dog, we even have far less genes dedicated to the cause, A long long long time ago when dogs evolved from their far-removed ancestors and humans began domesticating them, we shaped the dog to suit our needs. The first need was to hunt, to hunt they needed a strong nose of a hound to track, keen eyes and speed of a sighthound, and hearing to keep guard of livestock and people safe. Not only did we change the appearance of dogs we changed the shape of their brains! I think that is incredible; a hound has a larger olfactory bulb made up about an 8th in it mass which is proportionally bigger than our own. Then the sighthound who has a larger visual lobe at the back of the brain.
I say this a lot but if we do not see our dogs as dogs with their magnificent capabilities which are ever present how can we fulfil their needs. A dog needs to smell that lamppost/noticeboard and read its messages, why stop its biological desires, in doing so it does not harm us. It does not need to heel walk everywhere. It does need to have a run and find and follow scent trails, to fetch and carry suitable items in its mouth. And this is where training comes in and why it is so important. To allow freedom we need to know we can keep them safe and that they will listen and recall at any sign of dangers. See training is not about being the “Alpha” which is a crazy outdated and unscientific notion! It’s about working together, learning and understanding each other to get the best out of our relationships.
