a dog's nose and her sense of smell

Penny and I have fun playing scenting games. Two favorites start off with me telling Penny to 'wait'. In the first, I show her a piece of tasty food and let her smell it and then I go away and hide it somewhere up the other end of the house.

Penny puts her nose to the ground as she makes her way to where it is hidden, so I assume she actually follows the scent of my movements rather than the smell of the treat itself. When I tested this by adding a loop around our lounge room, she followed this trail exactly.

The second game involves me hiding at the other end of the house and calling 'come'. It's great fun to hide in cupboards and crouch down behind boxes, listening for the slow click, click of her nails on the floor as she searches. I feel young, rediscovering the excitement of a childhood game of hide-and-seek.

When we walk around the streets, if she is 'free' rather than being expected to 'walk nicely on lead', it's a slow trip, as she has to sniff every post, clump of grass, wall, lamp-post, rock...I'm sure you get the idea.

Smelling is obviously a delight to her. I read a fascinating description of the role of the sense of smell in a dog's life by Randy Kidd, DVM, PhD, at Whole-Dog-Journal.com

The summary at the end of the article says:

The dog’s nose may be his most powerful organ and it is certainly one of the most dynamic of all animal systems, with activities that range from basic smell detection, to sensing fear, to memory, to emotions, to mate- and pack-selection, on to a genetic history carried from one generation to the next. Fortunately, disease doesn’t often waylay its functional capability, and fortunately again, most of the diseases of the nose are easily treated naturally.

The entire article is worth a careful read, but some of the highlights for me were:

The dog collects scents by air-scenting (sniffing volatile oils that are traveling in the air) and sniffing the ground. A dog’s nose is ideally made for sniffing – the outer nares are mobile and allow for expansion on inspiration and contraction to prevent the entry of unwanted objects. When a dog sniffs, he inhales the scented chemicals into his nasal cavities, where they are trapped in mucus and processed by the sensory cells. Expiration forces air out the side of the nares so that its exit doesn’t interfere with odors still in the air or on the ground...

In addition, the dog has devoted a tremendous amount of his brain tissue to olfactory cells. (Some estimates allocate one-third of the dog’s brain to the chore of scenting.) All this adds up to a canine scenter that has thousands to millions of times the ability of his human counterpart...

In my opinion, the best “nutrition” we can give to a dog’s nose is a daily dose of natural odorants, generated from the fields and woodlands out of doors – the perfect way to build up the reserve of sensory cells and brain connections related to smelling.

An article called Dogs Smell!also has a discussion of dogs' sense of smell and there I read that different breeds have a stronger or weaker sense of smell according to the length of their nose - which seems pretty obvious. It's interesting, though, to wonder how these differing muzzle lengths come about, when all breeds of dogs are so similar genetically.In an interview with Raymond Coppinger, Juliet Clutton Brock and Robert Wayne,
Jonica Newbysays:

All dogs start life with a small muzzle. Then, at 8 weeks of age, the genes for growing noses suddenly switch on, until, from about 5 months they gradually switch off again.

But when you scramble the timing of those growth genes, you can get a long nosed dog. Or a short nosed dog. Or a dog that doesn’t grow up at all. That’s how nature gave us all these weird and wonderful shapes and sizes.