Show me, if you can, one scientific instrument able to detect and locate: blood and bodies, arson and ivory, pythons, truffles and bedbugs. These are among the scents dogs are being used to sniff out, despite a wealth of scientific research to find a mechanical alternative as effective.

Man has profitably employed dog’s scenting skills in the hunting and shooting field for many centuries, as the wide range of scent-hound and gun-dog breeds illustrate. Whatever their breed differences, scent hounds from Finland and France have the same priceless attributes, as have their counterparts in America and Istria. Setters, pointers, braques and épagneuls may vary from Ireland to Italy and from Hungary to Holland, but scenting success is the shared skill.

Perhaps the greatest failing of man in his understanding of dog is his recurring inability to appreciate how dominant the sense of smell is in the senses of the domestic dog. For man, the main detecting senses are sight and hearing.

Indeed, I have read scientific papers claiming that our sixth sense lapsed only because of the high-quality facility given to us by our eyes and ears.

I have also read articles in country magazines extolling the superb eyesight of dogs, which I find hard to justify. I have never come across a dog with better all-round eyesight than man, although we will never be able to match dog’s remarkable detection of movement. Never, too, will any of us match their quite astonishing sense of smell.

A dog-owning neighbour of mine was recently quite apologetic about always taking her dogs on the same country walk. Each time she walks that route, she sees the same scenes. But for her dogs, each of those walks is a different experience despite following the same route every day. For across that path, farm animals, wild creatures, other dogs and humans have moved and every day the smells will vary. This is the stimulation dogs react to, savour and need for the fullness of life. For the domestic dog, nose work beats watching TV by a mile!

Amazing sense of smell
The dog’s scenting powers have attracted the attention of scientists; Droscher in 1971 found that a barefooted man leaves roughly four billionths of a gram of “odorous sweat substance” with each step he takes. In 1933, Budgett found that water formed 99 per cent of such a gram in the first place. In locating this minute sweat sample, the tracking dog has to overlook the accompanying, conflicting and much more powerful surrounding smells – animal, vegetable and mineral… and most men on the run wear shoes! Experiments on puppies by Russian psychiatrists Klosovsky and Kosmarskaya led them to believe that the senses of smell and taste were so interconnected they were virtually acting as one, and could, in general, act interchangeably.

I have noticed when using dogs on a trail that the dog’s head is carried higher during morning tracking, perhaps because the air is rising, bringing the scent with it. It’s also noticeable that scenting ability varies from dog to dog, even within a breed. I suspect, too, that it’s the Bloodhound’s determination and sheer persistence as much as its scenting powers that makes it so effective at following cold trails. Using Labrador Retrievers as tracker-dogs in the Malayan emergency showed me that scenting prowess isn’t enough by itself; you need a fanatic like a Bloodhound for really testing trails. However, the contemporary physique bestowed on this breed for the show ring is a serious handicap in the field.

Research has shown that an amazing one-third of a dog’s brain is allocated to scent detection. The German Shepherd Dog has an olfactory area of 170 square centimetres, compared to a Pekingese’s 20 square centimetres. The Peke, however, still has five times the olfactory area of a human. Studies in Labradors revealed that: working lines produced the best sniffers; excessive attention-seeking was accompanied by poor search ability; dogs stressed by novel situations were less suitable for search work. The sheer sensitivity of the canine nose allows it to specialize in hunting deer or fox, otter or hare, man or truffles and to locate avalanche victims, drugs, the wounded on the battlefield, explosives, temporary graves, dry rot, melanomas, the onset of epilepsy… even moonshine in America.

Outstanding skill
The dog’s tracking ability has been used to show that identical twins produce an identical odour. A dog can follow the trail of either twin after smelling an article belonging to one of them, although cases have been recorded of a gifted dog actually differentiating between the two. This tracking ability can be impaired by temperature change, rain, humidity, frost, wind, competing odours and the sheer passage of time. But no human or machine would get on such a trail in the first place. This tracking skill backed by a dog’s response to training is a valuable element in the unique man-dog partnership. Pigs employed to locate truffles usually eat them!

In American Kennel Club tracking tests in 2005, nine scent-hound breeds earned 63 titles among them. Golden Retrievers earned 94 titles. They, along with Labradors and Malinois, are the favoured breeds in that country for drug, bomb or search-and-rescue work. Bloodhounds are famous for their ability to persevere with an original trail, with GSDs, Boxers and Dobermans more likely to be diverted by cross-trails. A Dutch Shepherd has been assessed as worth his weight in gold, after detecting millions of counterfeit dollars in the U.S. The U.S. Customs and Border Protection declared that dogs’ nose-skill leads to well over 6,000 arrests annually.

The Russian airline Aeroflot has helped develop a ‘super-sniffer dog’ in its campaign to defeat terrorists and drug smugglers. Crossing a Siberian Husky with a Turkoman jackal has produced a dog with scent-detection skills for extreme cold, which can suppress smells. The jackal’s nose is even more sensitive than the domestic dog’s, but the jackal is hard to train and afraid of humans. Husky blood brings low-temperature skills and greater biddability.

These hybrids can work in extreme winter temperatures. Each dog is estimated to be worth around $8,500 and other airlines in northern countries have expressed interest in them.

The more perceptive writers on dogs have long appreciated the overriding importance of the canine sense of smell. Wilson Stephens in his quite excellent Gundog Sense and Sensibility has written: “To gundogs, with centuries of nose-consciousness bred into it, noses are for serious business, eyes merely come in useful occasionally” going on to state that he had never needed to teach a dog to use its nose but usually had to teach one to mark the fall of game using its eyes.

‘Wildfowler’ in his Dog Breaking of 1915 gave his list of setter qualities in this order; “Nose, pace, energy, style and indomitable endurance” – no doubt in his mind of the value to man of dog’s sense of smell. But to limit scenting powers just to the nose is not entirely correct.

In his informative The Mind of the Dog (1958), R.H. Smythe recorded this information: “Now, odours, scents or smells represent the delights of paradise to every dog… it is well known that delicate smells make the mouth water. Saliva dissolves the scent-bearing vapours and so the dog not only smells them but also tastes them. It is believed that hounds use both smell and taste, especially when the scent becomes strong, and it is believed by many that when hounds ‘give tongue’ they are actually savouring the delightful odour as it dissolves in their saliva.” In pursuit of this belief, our ancestors utilized the “shallow flew’d hound” to hunt by sight and scent, in that order, as a “fleethound,” and the “deep-mouthed hound” as a specialist scent hound.

There’s a link, too, between well-developed sinuses and the ability to track. The best trailers have the skull conformation to allow good sinus development, adequate width of nostril and good length of foreface so there is sufficient surface between the nostrils to house the smell-sensitive lining membrane.

Scent hounds, gun dogs and other hunting dogs depend on the shape of their skulls for acute smell discrimination. In pedigree breeds, the standard’s wording of the description of the skull therefore relates to the scenting prowess of the dog.

The terrier’s narrower skull leads it to prefer hunting by sight, show less interest in following a trail of scent yet, through selective breeding, show enormous interest in scent coming from below ground.

Imagine the delicacy of scent that allows a gun dog, at some distance, to distinguish between a partridge and a lark, a pheasant and a woodcock. Writing at the turn of the century, Gen. Hutchinson in his classic work Dog Breaking (1909) advised hunting pointers and setters together, stating on the subject of scent that “on certain days – in slight frost, for instance – setters will recognise it better than pointers, and, on the other hand, that the nose of the latter will prove far superior after a long continuance of dry weather.” Different breeds often display definite strengths in such a way and so, too, do individual dogs.

Following a trail ‘hot-footed’ at great pace demands not only a ‘fast nose’ – i.e., superb coordination between detection and reaction, nose to brain – but also the anatomical capability of physical response. The legendary Foxhound, John Smith-Barry’s Bluecap (1759), took part in a famous match-race in 1762 over a four-mile distance on Newmarket racecourse. The ground was reportedly covered in just over eight minutes. Sixty horses started with the four foxhounds but couldn’t last the pace, only 12 finishing. Yet the hounds had to run and follow a trail! Bluecap, it was alleged, covered ground at a mile every two minutes, approximately the speed of a Derby winner. I wonder what time this hound would have achieved just running with its head up. His three-year-old daughter, incidentally, came a close second in this match.

But ‘flying the country’ is not the essence of scent-hound work; the skill in unravelling a confused scent, the music of the hounds and the teamwork of the pack is the core of hunting pleasure with hounds following by scent. ‘Questing and melody’ in such hounds has long been greatly valued and the considerable skill needed to pursue poor scent always much admired. In stag hunting, the most trusted hounds, the tufters, exercise great scenting skill in deciding on the right line to get the pack laid on and the desired quarry isolated from the remainder; only a dog can do this. The sensory skill of the domestic dog is simply sensational.

It could be that with the contemporary pressures on country sports, not just those arising from differing social attitudes but more from the increasing loss of country in which packs of hounds can operate, we need to find new outlets for hounds that follow scent. Hound trailing in the Lake District gives great pleasure to both people and hounds and offends no one. Perhaps a revival of match-races in which Foxhounds or comparable breeds take part in speed trials on draglines in the wake of Bluecap’s feat would fulfill a need. So, too, could scent-matches in which the slower foot hounds could prove the quality of their nose work on confused trails, where time was less important than accuracy. Come on, you fanciers of Beagles and Bassets, Grand Bleu de Gascogne and Hamiltonstovares, Ridgebacks and Podengos; even in show dogs, the heritage is there and the instincts merely dormant. Even Masefield pondered a century ago, on scenthound skills:

Whence this sagacity, this wondrous pow’r
Of tracing step by step or man or brute?
What guide invisible points out their way
O’er the dank marsh, bleak hill and sandy plain?

By Col. David Hancock
The author of seven acclaimed books on dogs and 500 articles published in a number of national magazines, Col. David Hancock, M.B.E., of Oxfordshire, England, has been studying dogs for 50 years.
(Appeared in January, 2007 issue)