Scents and sensibility

Every working dog uses one of its senses above all others – usually its nose, and sometimes its eyes or even ears. Here are the breeds by hunting style.

Clean booters

Confusingly bloodhounds do not hunt the smell of blood but other scents caused by human movement. Their name comes from ‘blooded’, meaning ‘pure-bred’.

Ground scenters

Labrador retrievers, spaniels, trail-foxhounds and draghounds primarily hunt with noses to the ground.

Blood scenters

Gundogs, especially retrievers, and deer-finding dogs such as dachshunds follow the strong blood scent of wounded quarry.

Air scenters

Pointers, setters and often flatcoat and golden retrievers can cover a wide area through air scent. These breeds also use ground scent when closer to the quarry.

Sighthounds

A group of hounds, including greyhounds, whippets and Afghans, that hunt a moving lure using sight and speed rather than scent.

As foxhunting was replaced by trail hunting, hounds had to learn how the unfamiliar artificial scent behaved

Hunting with dogs is one thing, and hunting with hounds is quite another. Dogs do things differently from hounds. Whether they are gundogs (spaniels or pointers, for example) or hounds such as foxhounds and bloodhounds, every breed and type of dog working in the field has its own approach. Modern bloodhounds have been trained to hunt the clean boot. Spaniels are best following bodily odours on the ground. Pointers are air scenters. Some hounds – greyhounds, for instance – are sighthounds and will ignore their noses in favour of their eyes.

In the bitterly divisive days when the Hunting Act 2004 was passed, one small detail was particularly hard for hunting folk to swallow. The phrase ‘hunting with dogs’ seemed deliberately calculated to cause offence: because foxes and other banned quarry were not hunted with dogs but with hounds. There is more to this than hurt feelings. Having a thorough understanding of the way different breeds and species use their senses is a huge element of successful fieldcraft, no matter what the sport. For anyone who works a hound or a gundog, the distinctions between how they find and follow scent are important, and humans must learn what a hound knows instinctively about scent.

Whippets excel in lure coursing, where sight is used in the chase

A dog’s sense of smell

Scent begins its life as an organic compound of chemicals contained within a molecule. Scent molecules have many different homes (the medium) from where they gradually diffuse into the environment. Depending on conditions, many get swept into the air or washed away completely but most odour molecules are attached to the ground or objects on the ground. This is where they encounter an extraordinarily complex piece of biotechnology called a nose, which has a hound, gundog or detection dog operating it.

A dog’s primary scent system consists of up to 300 million cup-shaped scent receptor cells that capture molecules of smell as they enter the nasal organ. The information from the scent receptors is sifted many times and eventually reaches the areas of the brain devoted to processing smell. As much as one-third of a dog’s brain is devoted to olfactory cells performing this task. In addition, dogs have a vomeronasal organ (VNO) that is used for detecting pheromones. This is located inside the nasal cavity, and some breeds can flare their nostrils and open up their palate to suck the molecules into the VNO. How the dog finds the scent in the first place, and what it does with it then, is up to humans who have used a dog’s sense of smell since prehistory.

Weather can have a big impact on scent

Versatile scenters

Among the original – and still the best – of the hunting hounds are the bloodhounds. Luckily for hunting folk, they have also proved to be versatile and adaptable scenters. According to the Masters of Draghounds & Bloodhounds Association: ‘The bloodhound possesses the keenest sense of smell of any other dog breed and can track scent that is many days old over considerable distances.’ This superior scenting power is why bloodhounds have been used to track men for centuries but not how they got their name. The chien de Saint-Hubert ended up being called the ‘blooded’ hound because of its pure blood, as opposed to the many outcrosses producing other breeds of hunting hounds. Bloodhounds certainly don’t follow the scent of blood. They are much more discerning than that, as Jeremy Whaley, Joint Master of the South Downs Bloodhounds, points out. “The biggest mistake people make about hunting the clean boot is that they think it can be compared with, and is therefore similar to, hunting wild animals before the Hunting Act 2004,” he says. “Humans run with clothes and shoes on, therefore scent-producing matter in the environment is smaller and cleaner than with most animals. Clean-boot hounds learn to adapt to poor scenting conditions and are able to pick up the line of broken ground scent where the runners have crushed vegetation and soil.”

The only other canines that can compare with this are the detection dogs used to hunt out drugs and explosives. Eric Burchell, owner of Advanced Canine Technologies, reveals: “Detection dogs are PhD-level scenters. The way we train a dog is to modify its natural quality. You have to imprint the dog on the target odour and when it finds, you reward. We don’t use food treats, which can be distracting; instead, the best rewards are a tennis ball or a towel. You can train up to nine or 10 different odours within a group of smells such as the opiates. It is quite technical.” Burchell also trains and works his Bournepark Gundogs and, although most detection dogs are from gundog breeds, there is more to it. “You have to have a dog that is tough,” he explains. “They are working in difficult environments all the time and they have to be athletic, strong and confident.” Then Burchell can work with the scenting DNA of the gundog breeds: “The spaniels are ground scenters working from body-borne scent given off by the quarry. They find at ground level and you get a visible behaviour change. In a good scent the flavour of the game changes, and the dogs can tell that. For example, a wounded bird gives off a blood scent that is very strong for a dog. Cocker and springer spaniels find that easier because they have generations of breeding for that.”

Jane Manley, of the Flatcoated Retriever Society, agrees that various types of scent can be easier or harder for different breeds of dog. “I work flatcoats, labradors and spaniels, and it is noticeable how they each can appear more or less efficient at their job depending on scenting conditions,” she says. “It’s impossible to predict who will be top dog on any given day, as scent is so unpredictable. Sometimes a breeze seems to be an asset; another time the difference between ground and air temperature seems the major factor. An air-scenting dog, such as a flatcoat or a golden retriever, will benefit from a breeze carrying scent to them and they work the wind accordingly with a higher head carriage, while a spaniel will quarter more closely with its nose down for the best result.”

Pointers use air scent to locate their quarary

The most famous of the air scenters are the pointers and setters, surely also the most romantic as they range across the open hill, noses into the breeze, questing for grouse. Jon Kean is fortunate enough to have had many such days with his pointers. “The pointer is a hunting machine with great game-finding abilities,” he says. “I like a pointer that quarters the ground in systematic fashion, carrying a high head. When they go on point, you’ll possibly see their flews (upper lips) parted to taste the air. You just know they’ve got the scent of grouse up those wide, flaring nostrils.” The mystery of scent is a good talking point, he adds: “For example, you will get days when well-trained dogs either bump or miss game entirely. Then it is fair to assume that the scenting conditions have been poor, and the topography of the ground can have an impact as well. The days I like best are cool with a gentle breeze and moisture on the ground – good conditions for a working pointer. I wish I knew more about scent but I always trust the dog to find the grouse.”

Air scenters usually range quite widely with their noses up, unlike the ground scenters that must have their heads down. The next adaptation for a head-up dog is to leave scent behind almost completely and hunt by sight, as the gaze or sighthound group has done. Sarah Meadham competes her whippets and is a founding member of UK Sighthound Sport. She explains the distinction between scenting animals and the sighthounds: “Like all dogs, sighthounds have an incredible nose. Naturally they use their nose to pick up scent of prey but sight is where they excel, and usually if they lose sight of their prey they would give up a hunt. However, in lure coursing, the artificial ‘prey’ (usually shredded plastic) doesn’t have a scent, so purely sight is used in the chase. When handlers are ready, the lure is mechanically pulled away at speed, which triggers the dogs’ desire to chase.”

The scent-hound equivalent of this is drag hunting, which became popular with the military from the 1860s. The Staff College Drag Hunt, based at the Royal Military Academy Sandhurst, explains that the relatively short amount of time needed for drag hunting and the intensity of excitement is a plus for soldiers. It was even possible for units to get out drag hunting while stationed in Germany and Italy following the Second World War. It’s quite straightforward too, says huntsman Gary Thorpe: “Hounds follow a scent laid by a runner dragging a bag soaked in ‘the smell’. The scent is artificial and is made from a mixture of water, oil and perfume – all purchased from our local supermarket.”

Labrador retrievers and spaniels are ground scenters

On the trail

Trail hunting using foxhounds isn’t so simple, according to former Master of Foxhounds Richard Standing, who has hunted foxhounds as an amateur huntsman both before and after the Hunting Act, and remembers the difficulties of trying to hunt an artificial trail using foxhounds trained for generations to hunt a live fox: “The switch was problematic. Foxhounds are like sheepdogs. They are naturally going to do something – hunt or herd – and over the years we educated them to hunt one thing. The way you train a young foxhound is through peer pressure. The older hounds know what to do and the younger ones learn by copying, which enters them to scent.”

With inexperience came the added difficulty of both hounds and humans having to learn how this unfamiliar trail scent behaved. “Even within a day’s hunting, things can be unpredictable,” explains Standing. “Different quarry smell different. With a red stag the scent will stay for hours, whereas a simulated fox scent, depending on conditions, will only hang around for 30 minutes. A red stag might have moved on an hour earlier and the scent is still there, meaning you have to stop hounds. The more you have to stop hounds the less drive and confidence they are going to have, and I think we are certainly seeing a loss of drive among hounds.”

Trying to overcome some of these issues, modern trail hunts lay several fresh trails throughout a day; and two or three hound generations into trail hunting, the foxhound is evolving into a trail-foxhound. But the complexity of what goes on in a hound’s nose remains more daunting to understand than any Westminster politics.