YOUR DOG'S SENSE OF SMELL
SCENT IS THE MOST HIGHLY DEVELOPED OF ALL A DOG'S SENSES
HOW A DOG'S NOSE WORKS
When a dog takes a short deep sniff (rather than normal breathing) moisture on the surface of a dog's nose helps to capture scent molecules in the air and dissolve them. These molecules then come into contact with the olfactory membranes deep inside the dog's nose which send nerve impulses to the olfactory centre of the brain (which is forty times larger in ratio to the olfactory centre of a human brain). These nasal membranes cover the nose's wafer-thin turbinate bones and have convoluted folds to ensure that the minutest amount of scent can be captured within them and assessed accurately.
Dogs also have the ability to detect sex scent as the molecules in the air come in contact with the roof of their mouths and trigger the vomeronasal organ situated there. This organ transmits information directly to the limbic system of the brain which controls the dog's emotional behaviour.
Swedish scientists have recently discovered that dogs have heat (ie. infrared) detectors alongside the scent receptors in their nasal cavity. This enables hunting dogs to sense a prey's body heat when the dog is downwind of it.
EXAMPLES OF HOW ACUTE A DOG'S SENSE OF SMELL ARE
Scientist have proved that a dog can detect one part in a million of scent in distilled water. This ability to detect and differentiate scents has resulted in dogs being used throughout the world for detection and rescue, not just for hunting.
- Dogs have been successfully trained to detect land mines even when the mines are buried in the ground over long periods of time. Anne-Lill Kvam from Norway (a Full Member of the Pet Dog Trainers of Europe), who help set up the training programme in Angola to teach dogs to detect mines, gives lectures all over the world helping dog owners and trainers develop a deeper understanding of how dogs use their sense of smell.
- Look at the article "With training, a dog's nose almost always knows"
- "Why Beagles as detector dogs"
- Canine Search and Rescue Tribute to the dogs and handlers that worked at the World Trade Centre after 9/11
- National Search and Rescue
Dogs detect scent molecules in two different ways - sniffing the air for traces of a particular scent, or from sniffing the ground or objects with scent on. Some dogs seem to have a preference for air scenting or ground scenting but all dogs are capable of doing both to some degree or other.
Air scent occurs when a disturbance is made by whatever has recently passed through the air (eg. an animal, human, or a toy that has been thrown for the dog to retrieve - see Find It). It is affected by atmospheric conditions - temperature, humidity, wind speed and direction - and the time that has elapsed since the air was disturbed. Air scent disappears more quickly than ground scent.
- Your dog can detect the scent of any treats or toys that you are carrying in your pockets, hands, bumbag etc. As soon as you begin your walk, your dog will know exactly what you have hidden around your person for its reward for "good behaviour". This is why so many dogs do not come back when called - they already know what the handler has to offer them and there is no element of surprise or anticipation for the dog. This is why our treat boxes are so effective - the dog cannot detect what type of different foods the handler is carrying until the lid is taken off. I always enjoy watching a dog's look of surprise and sudden interest when a treat box lid is opened and it suddenly detects all the different and enticing food scents that suddenly appear in the air around the handler. Don't underestimate the power of a pleasant surprise on a dog's sense of smell when you are training a dog - it can be an extremely effective photo!
- Another misunderstood aspect of the sensitivity dogs have to air scent is when dogs bark "for no apparent reason". What is actually happening is that the dog is detecting the scent of other dogs (and/or humans) that are passing its territory, even when the doors and windows are tightly closed or when the "intruder" is a long distance away. I have plenty of instances where dogs that are in houses, sheds or kennels detect the scent of passers by in the wind and begin barking a territorial warning, or bark to communicate as the dog feels lonely and stressed. An amazing example of this is when I am walking my dogs on the Malvern Hills and we come to a valley where houses are built at the very bottom and are a great distance from the high path that we walk on. As soon as we turn into this part of the Hills a household of dogs that live at the bottom of the valley begin howling and barking (what the neighbours think I can't imagine as there is no way that they can see us walking on the path above!) and stop as soon as we have walked downwind of the property.
- Dogs use scent a great deal when compiling
environmental photos of enjoyable or threatening events to
store in their long-term memory.
One of the most obvious examples of this is when driving your dog
to the seaside, or agility shows, that it has visited in the past.
The dog can detect the same environmental scents in the air as it
did when it last visited the location and this photo triggers
anticipation and excited behaviour from the dog.
- DISTURBANCE - Scent molecules are left on the ground by an animal or human disturbing the surface as it walked across it. For instance, blades of grass would be crushed, earth disturbed by the weight of the human or animal, fallen leaves moved or crushed, twigs and stalks snapped and bruised.
- ANIMAL "DUST" - Animals leave minute fragments of skin, feather or fur (and pheromone scents) as they move across the ground and a dog can detect and recognise the subtle differences between not only species but specific animals as it follows this trail of dust particles.
- HUMAN "DUST" - Humans not only leave fragments of dead skin and
hair behind them, they also leave particles from their clothing,
footwear, and the manmade scents that they are wearing such as
perfume or deodorant. Dogs are also able to detect the emotional state of the human it is tracking
by the scent of the pheromones in the air or on the ground.
Tuna Tracking mimics ground scenting by leaving a very unusual but highly stimulating ground scent which the dog has usually not come across before. The dog soon realises that this exciting scent game only happens when their handler is around and so it builds a strong bond with the handler and the dog is far less likely to wander off and "read the newspaper".
One of the biggest and most enjoyable benefits of watching your dog working with its nose is that you begin to understand and learn about your dog's body language and relate the same signals to other aspects of the dog's life.
For instance, dogs often hold their tail in a particular way when they are really concentrating. I have noticed this with one of my collies who loves to play all sorts of different nose games with me - when he is really focused he raises his tail very high and curves it over his back. I recognised the same body language when I was teaching him to go over a dogwalk in agility and realised that he was concentrating just as hard on learning this new "game" as he was when following a scent. I recognised his concentration and commitment and gave him plenty of praise and reward for working so hard.
Other changes in body language that you may see in your dog when using its sense of smell are -
- Whole body rigid and still as the dog sniffs the scent either on the ground or in the air.
- Mouth open to catch more scent molecules in the roof of its mouth
- Licking its nose to keep it moist so that it can dissolve more scent molecules
- Suddenly standing still, and perhaps raising a paw as if in mid-stride. This behaviour is encouraged and bred into pointing and setting dogs that have to detect prey with their noses then stand perfectly still and rigid, pointing in the direction of the prey's hiding place. They have been bred to stand still for long periods of time until the hunter arrives and drives the prey out with flushing dogs so that he can see and shoot the prey. This is the reason why so many setting and pointing dogs get "lost" on walks in the countryside - they catch the scent of a nearby animal and stand and "point" or "set" until their handler comes to release them. Unfortunately the handler may not be able to see the dog's body language and will shout and whistle to try to get the dog's attention and return to them, unaware of the dog's need to be released from its working stance.
DON'T TALK OR MOVE - IT WILL DISTRACT YOUR DOG!
Dogs need and enjoy using their brains to detect, analyse and assess scents in their environment. However, they are unable to concentrate properly if they are distracted by movements or sounds from nearby. Therefore, resist the temptation to talk to your dog in any way until the dog has found the end of the track, object or finished the exercise. If you praise your dog by saying "good boy" while it is still working, it will stop sniffing the ground as these words are usually said as a release command to finish a training exercise. Also try to keep your body movements to a minimum when your dog is deep in concentration.
- Weather conditions - dry, wet, cold, warm, snow, rain, fog, mist, sun, wind
- The age of the track - ie. the time between when the track was set and when the dog was asked to find and follow it
- Ground cover - straw stubble is very sharp and unpleasant against a dog's nose; it is far harder for a dog to find a follow a track over long grass rather than short grass; twigs, leaves and branches can be distracting for some dogs when they are learning scent games.
- "Shouting" in scent terms - newly dug or ploughed earth and cut grass both give off very strong scents that can overpower a dog's sense of smell; animal or human tracks either crossing or on top of the track (ie don't do subtle scent games near paths or busy thoroughfares).
- Overpowering strong manmade scents - eg. petrol, fresh paint, tar, room or air fresheners, scented candles, essential oils, household cleaning products etc - are another "shouting" problem for dogs. Some dogs can be especially effected by strong scents, such as dogs in kennels with strong disinfectant, creosote or timber preservatives in their everyday environment. Meanwhile some dogs have very strong reactions to certain scents (lavender for instance is supposed to be a calming essential oil, but it can cause sudden anger for some individuals!) So many of these strong smells can hinder a dog's sense of smell (for an hour or more) and result in them being unable to use their noses effectively.
- Pollen can aggravate the membranes in a dog's nose, while citronella is a skin irritant and can be particularly painful when inhaled into the dog's sensitive nose. Also beware of products containing Tea Tree Oil as there have been cases of dogs showing adverse reactions due to the quality and strength of this highly overused natural oil.
Dogs are able to cope if they lose their sense of taste, hearing or sight but find life extremely difficult to cope with if their sense of smell is impaired or lost - it is the equivalent of a human becoming deaf, dumb and blind and having to live alone in modern society.
One of my dogs wears a plastic "basket" type muzzle when walking off-lead, yet he has no problems at all sniffing around and following any scent or track that he comes across. He wears the muzzle because when he is excited from chasing rabbits or squirrels, his adrenaline levels rise sharply and he occasionally chases after cyclists or joggers that happen to be passing at the "wrong time or place". With the muzzle on I have no worries about him causing any harm to anyone (or rabbit or squirrel!) and can allow him the freedom to exercise his body and mind in a safe and controlled manner.
WHAT DOGS USE THEIR NOSE FOR
IN THE BEGINNING....
From the moment that a puppy is born the first sense it uses is scent as it blindly searches for its mother's teat and begins to suckle. This is the puppy's first Environmental Photo - the smell of the milk and its mother, the taste of the milk in its mouth, and the heat and physical closeness of its mother are all perceived as very rewarding and pleasant and will be remembered for the rest of the dog's life. Over the next couple of days the puppy will depend solely on its sense of smell to explore its surroundings and these early "photos" can have a profound effect on the puppy's development and how it will perceive its world for the rest of its life.
With this in mind, an old towel with the breeder's scent on it (and later on the pup's prospective new owner's scent) can be left in the whelping box so that the puppy builds up strong and happy associations ("photos") with the scent and will feel at ease when they meet the humans. However, make sure that the towel does not have a strong chemical scent on it that will "pollute" the human's scent that you are trying to introduce to the puppy.
Also be aware that too much exposure to too many scents can confuse and stress puppies and so I recommend the introduction of ONLY ONE ORGANIC TYPE SCENT A DAY that the puppy will eventually come in contact with as it grows older. For instance, the saturated scent of one of the following can be put on the tip of a cotton bud and held in front of the young puppy's nostrils. Make sure that the puppy does not come in contact with the cotton bud (there may be harmful germs present) and that the puppy is not held or restrained - otherwise it may build up unpleasant associations with the scent and affect the puppy's behaviour when it comes across it later on in life. Instead, the breeder should stroke the puppy in a calm and pleasant manner so that the puppy feels confident and at ease with the new and exciting scent.
- Human scent* - Get the human to rub the cotton bud in their hand and then seal the cotton bud in an air tight container by itself until it is presented to the very young puppy (ie Seal & Keep).
- Foods* - Rub the tip of cotton bud on the puppy food that it will eventually be given when it is older the Seal & Keep. Also introduce it to the interesting smells of foods that it may be given as treats when it is older by rubbing the tip of the cotton bud on a bit of cheese, cooked meat etc.
- Compost - Push the cotton bud tip into your compost heap so that it can smell the "exciting" scents of rotting vegetation then Seal & Keep.
- Fresh or dried grass - Rub the cotton bud tip on your lawn, or on hay or straw, then Seal & Keep.
- Seaweed - If you have access to the seaside, rub a cotton bud tip on a piece of seaweed then Seal & Keep.
- Flowers* - Using only one type of flower at a time, rub the tip on the flower head so that it picks up the scent, then Seal & Keep.
- Other dogs* - Rub the cotton bud along the dog's fur so that it picks up traces of the dog's scent. You can also gently rub it on the dog's paw (where it is able to sweat). Seal & Keep.
- Rubber, Leather, Wool, or other materials* that it's toys will be made out of. Seal & Keep.
- Raw fish - Another exciting smell that will stimulate the young puppy's sense of smell. Rub the tip of the cotton bud on the fish then Seal & Keep until required.
* Only one variety of the scent on the cotton bud at a time.
MORE EXPERIENCES AND THEIR BENEFITS
When the puppy is weaned and introduced to its new home more interesting scents should be left on a variety of different articles, once again one scent at a time. For instance, put an interesting new scent on -
- Pieces of different textures of material
- Various surfaces in the garden
- Rubbed into raggits or grabbits that the handler plays with the puppy - but do not leave these training aids unattended as they will soon be chewed and destroyed!
The puppy can then be introduced to various Mind Games to help it develop and explore further its amazing sense of smell . This can also be done with dogs of any age or background.
There are many amazing benefits of introducing new and interesting scents to dogs rather than just letting it make its own entertainment by "Reading the Newspaper". The dog -
- Builds up a strong bond with the handler who provides such interesting scents and games for the dog to do while the handler is around. This is particularly true for dogs that have very little mental stimulation in their everyday lives, and those dogs that have become Lodgers.
- Will make a conscious effort to lower its levels of stress and adrenaline in order to concentrate on the scents that it is trying to analyse. This is one of the most effective ways of "de-stressing" dogs which are displaying "unwanted behavioural problems" and are in fact symptoms of stress.
- Gradually builds up the mental capacity to concentrate for longer periods of time. This ability can then have a profound effect on the dog's more traditional training (eg. staying in one position until it hears or sees your next command, doing a chain of exercises such as obedience or agility).
- Finds scent work helps to stimulate its mind and fulfill its working instincts. Many breeds and types of dogs have been bred for hundreds of generations to do particular work for humans - see Instincts. Most of these dogs are now kept as pets and have very little opportunity to fulfill their original working drives. However, a Mind Game session once or twice a week where the dog is using its brain and senses to their utmost limits not only tires the dog far more than a hour or more strenuous exercise, it feels as if it has used these working instincts and can really rest and relax until it is asked to "work" again later in the week.
Some breeds, such as scent hounds, have been specifically bred to have very high nose sensitivity and these breeds often have the distinctive appearance of having either -
- Big droopy (and usually drooling!) jowls hanging down from their upper lip
- Extra folds of skin around the face and/or neck which fall towards the ground as the dog lowers its head
- Long pendulous ears that touch the ground when the dog is sniffing.
The jowls, ears and folds of skin act like an umbrella around the dogs amazingly sensitive nose, enabling the dog to confine the scent molecules on the ground without the wind blowing them away while their ultra efficient wet noses detect the slightest scent so that it can be analysed and assessed by its brain.
HUNTING AND TRACKING
Tracking dogs, such as the Bloodhound or the Elkhound, have been bred to have phenomenal powers of mental and physical stamina so that they can concentrate on following one particular scent over long distances without being distracted by any other scents that they may detect while tracking. Depending on weather conditions and the terrain that they are working on, these dogs are able to follow tracks that are sometimes over 24 hours old and can differentiate between old tracks and those that have been made more recently.
On the other hand, flushing dogs are bred NOT to concentrate on following just one scent but to move quickly and erratically in the undergrowth and drive the prey out for the hunter to shoot. I use the phrase "Spot Scenting" to describe the brief and random thought processes that these dogs have for any one particular scent, or use the analogy of a butterfly moving haphazardly from one flower head to another in its search for nectar.
COMMUNICATION - "READING THE
Although it is fairly obvious that dogs use body language and sound to communicate with one another, we often misunderstand how important scent is for communication between dogs and, to a lesser extent, other animals. Scent is a major factor in a dog's social development, not only as a puppy but throughout its life.
Dogs communicate by leaving their scent in six different ways -
Some dogs have got "weeing" off to a fine art! My 11 year old dog has always had amazing bladder control and will store up vast quantities of urine for over 12 hours so that he can urinate at various strategic places on his fairly long walks off-lead on the Malvern Hills (eg. gateposts, specific trees or rocks, lamp posts etc). I only realised how much his bladder could hold when I took him to a training venue one morning and he realised that he was not going for a walk and proceeded to empty his bladder for 2 or 3 minutes so that he could concentrate on "working" with me in the training area.
Our young bitch, on the other hand, has a crafty trick of drinking from puddles and then urinating in them so that she leaves a "very big scent message" for the other dogs to sniff (but not necessarily drink from!).
Yes, dog "poo" is smelly, disgusting and a health hazard but every living creature has to get rid of its waste products somehow or other! However, dogs also use their faeces to act as another source of leaving their scent in the environment. Some dogs seem to enjoy analysing what the other dog has eaten by sniffing their faeces and can sometimes progress to enjoying the smell and taste so much that they eat the faeces.
- Anal glands
These are situated either side of the dog's anus and produce a very smelly secretion with the faeces. This strong scent is another way for a dog to leave a "message" on the environment.
- Scratching the ground
Some dogs scratch the ground after relieving themselves (with grass and leaves flying everywhere - and sometimes faeces as well!). Scratching and disturbing the earth, grass and other vegetation makes the "scent message" all the more noticeable and intriguing for any other dogs that come along afterwards.
- Rubbing themselves against something
Just as cats rub themselves against objects to leave their scent behind, dogs sometimes rub themselves against boundaries, humans, furniture etc in order to leave their scent on them. They may also do this in order to rub and massage themselves as well - dogs love to be touched!
These are external chemical messengers that enable dogs to detect various emotional states of not only dogs but humans as well (see Human Emotions such as Fear (and Happiness)). Pheromones help dogs to detect another dog's gender and sexual activity (eg. if a bitch ready to mate), levels of stress, fears or aggression, as well as calmness, relief, being relaxed etc. There is a very moving example of how pheromones effected two different dogs in very different ways in Our Dogs section of the website.
Because a dog's sense of smell is so acute, it is able to differentiate another dog's -
- Identity - is it friend, enemy, a newcomer or prey? If the dog considers the other dog as a friend and part of its pack, it will overmark the scent with its own so that both scents merge and become a new "identity" to any other dogs that come across the scent.
- Age (ie. puppy, juvenile, adult, or veteran) and therefore its rank or status not only in its "pack" but in the neighbourhood it lives or exercises in. More assertive bitches (and dogs) mark more than submissive ones.
- Gender - male or female, neutered or entire.
- Emotional state and levels of stress - depressed, anxious, overexcited, happy, contented and relaxed. These are all detected through pheromones (see above).
- Sexual arrousement
- What its diet consists of.
I like to compare this sniffing to humans reading - hence my expression "reading the newspaper" - and the scents that they leave behind "writing on the newspaper"! It is a vital part of a dog's life that it is able to "read" and "write" as it enables the dog to communicate with other dogs without having to physically be there. What dogs find so rewarding and satisfying about "reading the newspaper" is that every dog's "scent message" will be subtly different from the ones it did the day before. They enjoy the mental stimulation of reanalysing the scents to search for these subtle changes.
A classic example of dogs "reading the newspaper" is when I return home after training and/or being near to other dogs. My three dogs take great delight and concentration in sniffing me (especially my hands and trousers) to find out everything they can about the dogs I came in contact or close proximity too.
|Many dogs are also apprehensive about coming too close to another dog and enjoy communicating by sniffing the other dog's scent "messages" and leaving their own "message" for the other dog to smell later on. This "reading the newspaper" is particularly useful when introducing dogs to a new neighbourhood or training venue (see Where and When), as the dogs can learn a great deal about each other by sniffing each other's markings before actually meeting and displaying body language to each other.|
Dogs can become very frustrated and/or lonely because of the huge gulf of misunderstandings and lack of communication between themselves and their human "pack" (see Lodgers). For instance -
- The dog's calming signals are often misunderstood or ignored
- It may be given sufficient physical exercise while being walked on a lead but not be allowed to sniff the environment and thereby stimulate its brain and fulfill its working instincts
Therefore, detecting and analysing scents of other dogs can be even more important to these dogs who are starved of communication and welcome any type of contact with their own species.
Dogs also leave their scent to mark the boundaries of their territory. This warns other dogs to respect these boundaries and not to trespass. This is often backed up with barking if dogs come too close to their territory.
HUMAN EMOTIONS SUCH AS FEAR
Dogs are also able to detect the human's pheromones caused by stress, excitement, anger, anxiety or apprehension. This is why dogs become fearful or aggressive when they are close to humans that are nervous (often because the human has been bitten or frightened by a dog in the past). The dog recognises the scent of fear on the human and thinks that they are going to attack the dog, so it attacks first in "self defense". This is also true for dogs that are fearful of other dogs - they become "victims" and are attacked by other dogs because they can detect the fearful dog's pheromones either on the ground or in the air and believe that it will attack them.
One sad example of a dog picking up a human's apprehension was a dog I knew that became fearful and withdrawn whenever the handler walked down steep slopes while walking the dogs. The dog picked up the handler's fear of falling over and became worried as well, even though it did not understand why the situation was fearful.
On the other hand, dogs can also be positively affected by the scent of pheromones given off by emotions such as calmness, happiness and contentment. If humans feel relaxed and calm, their scent triggers similar behaviours in their dogs as well.
Dogs will also sniff the ground to diffuse a stressful situation (see Calming Signals). The dog itself may be stressed and so it sniffs the ground in an attempt to find a pleasant experience or photo that will distract it and help lower its stress levels. In other instances, the dog may pick up the stress pheromones in a human and try to calm the human down by displaying this calming signal.
A human equivalent of this displacement activity is idly drawing or doodling as we think, twisting our hair in our fingers, rattling keys or coins in our pocket, or constantly playing with komboloi (Greek worry beads).
Because dogs have far more sensitive noses than their rather limited taste buds, the scent of their food is far more important than its taste. This is why dog food manufacturers sell so much processed dog food, as cooked meat smells far more appetising and palatable than raw meat (although cooked meat has far less nutritional value than raw and therefore has to have artificial additives added to the pet food).
A practical example of how dogs love to use their sense of smell
is the use of Treat Boxes in training.
Rather than giving a treat to the dog in your hand, a tiny tasty treat is placed in a sealed treat box so
that the dog cannot detect what treats the handler has on their
person. When it is time to reward the dog the handler bends down
and holds the treat box so that the dog can "steal" the tasty treat
out of the box, licking and sniffing it inside and out just to make
sure that the very last molecule has been licked from it. Even
though the treat is gone in an instant, the whole process of
sniffing and licking the box is very exciting, stimulating and
rewarding to the dog and is a very strong
motivator. Make sure that you have a wide assortment of scents
of treats to choose from when placing the tiny morsel of food in
the treat box - after all if the same type of food is given each
time as a reward, there is little or no anticipation for the dog -
it already knows what the treat is going to be as the handler gave
it to them last time....
In conclusion if you find that your dog is sniffing a lot you may have to ask yourself these questions -
- Is the dog bored and therefore it uses its only opportunity to stimulate its brain and fulfill its working instincts while out on walks? Try Mind Games.
- Has it become a lodger because there is a lack of communication between what the dog's expectations and requirements are and that of the humans? See Lodgers to find out how to overcome this problem.
- Is it sniffing the ground in an attempt to resolve the stress and conflict it perceives around it? See Calming Signals.
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