What is Headspace?

Headspace is Amber Marks's satirical account of her research into the policing of smell - she uses developments in smell research as an allegory for the surveillance society. Amber was working as a barrister when she started spotting sniffer dogs on her travels to courts in different parts of the country. Disturbed by the implications for civil liberties (who needs a warrant when you've got a dog) and cynical about the supposed infallibility of canine intelligence (barking up the wrong knee), Amber started researching the phenomenon. To her amazement she discovered that across the world, people are being convicted on the word of a dog alone - despite the science of smell (the fascinating history and advances of which are all included in this book) being very poorly understood. As a legal expert on canine evidence, Amber is invited to a Ministry of Defence conference where the security applications of mice, moths, salmon and plants are discussed. That's when Amber's research journey really begins.

Q & A with Amber:

Why did you call the book "Headspace"?

Quite a lot in the book is about the importance of pscyhological privacy to human liberty and autonomy. Headspace - in 1960s jargon- means psychological privacy, the cognitive shed required for the development of an individual personality. When an entomologist told me that 'headspace' is also the technical term for the area surrounding a subject in which their smell can be detected and analysed - I knew it had to be the title of my book.

What did you enjoy most about writing this book?

I enjoyed everything about it. I enjoyed befriending security agents, police officers and scientists (they have all taken the fun I poke at their research in good humour). I enjoyed researching all the novels relating to the sense of smell (Perfume, Jitterbug Perfume, Brave New World, Oryx And Crake and millions of others) and learning about the science of smell. It was a great excuse to read Arthur Koestler's Ghost in the Machine and learn about bee brains and the manipulation of instinctive behaviour.

What is Dogwatch?

Dogwatch is the name of a secret organisation in Amber's book. It monitors potential threats to Headspace and seeks to inform people of their rights in these confusing times. It is presently focused on developments in surveillance, forensic science, less than lethal weapons, the militarisation of biology and the science of smell. Membership is easy- just send your findings to Amber and automatically become a member!

ACPO Police Dog Training and Care Manual

Dogwatch has received numerous media requests for this document- which is increasingly difficult to find on the internet. Dogwatch has decided to post the most interesting paragraphs from the Manual:

Regarding the use of Passive Alert Narcotics Detection Dogs: -

It should be recognised that all officers engaged on a passive alert dog operation should be fully briefed as to the capabilities of a passive alert dog team and each officers individual responsibility to complete the appropriate documentation in accordance with the Police and Criminal Evidence Act and the Codes of Practice.

All officers must be aware that the use of Passive Alert dogs does not constitute a search. The dog is deployed to scent the air surrounding an individual person and indicate the presence of the smell of category A and B narcotics in the close vicinity of an individual person giving a spontaneous indication on that person.

The indication of an individual person given by a Passive Alert dog provides grounds for a physical search. If the search is not undertaken solely on the indication given by the dog, but an attempt is made to support the dogs indication, i.e. by questions and answers the suspects comments may remove the reasonable grounds by which a search would have taken place.

The Passive Alert dog works in a completely non-discriminatory manner. Ensuring that the dog randomly scans people should support this. Therefore people may not be funnelled or individuals requested to change their direction in order to facilitate the dogs deployment as this may constitute a search.

Extensive training records, and records of operational deployments, should be maintained at Service level to support the evidential credibility of Passive Alert dogs. The Supervision of these records will rest with the Nominated Officer.


The training of dogs is not a problem which can be solved with a mathematical formula. The temperament and individual characteristics of each dog must be considered and the training technique varied accordingly. When a handler knows what to expect from the dog, and what the dog's reactions are likely to be, the handler has the advantage. Experience will enable an observant handler to anticipate a dog's next move and will help the handler to decide whether to force an issue or whether to modify the demands. Knowledge of dog behaviour does not come easily and can be acquired only by diligent application and study of all matters connected with dogs, but it is essential if a handler is to get the best from the dog. The following principles of training should be carefully studied.

1.1 Control

Control is the major factor in training dogs; self-control on the part of the handler as well as control over the dog. Self-control requires that handlers must, at all times, have complete control over themselves. A handler who loses their temper during the training period will also lose control of the dog. When this happens, the angry reprimands, shouting, jerking and repetitions which follow will do nothing except confuse the animal. The aim is to train the dog and not constantly reprimand it. An important point to bear in mind is that when a dog fails to obey a command, there is always the possibility that it has not learned properly. Right from the beginning of training, a dog should never be permitted to ignore a command or fail to carry it out completely. The dog must learn to associate a command with its performance of it, and must never be allowed to suspect that there is anything it can do but obey. Furthermore, the dog must learn that it will have to do what is commanded, however long it takes. Laxity on the handler's part, on one occasion only, may make such an impression on a dog that difficulty in maintaining the continuity and standard of training may easily ensue. All new exercises should be started when the dog is restrained and controlled, if the acquisition of bad habits is to be prevented. The handler must be patient until each exercise is brought to a successful conclusion. A dog can sense any change in the handler's attitude and, if it does this, it becomes more difficult to handle. Patience is a major requirement in training but, at the same time, it must be coupled with firmness. The moment it is certain a dog knows that should be done, instant obedience must be demanded and obtained. The result will be a prompt and accurate worker. Dog training takes much time and understanding. Training periods should be pleasant, so that both handler and dog will look forward to learning new tasks. Once this atmosphere is established, the dog will begin to enjoy training, and the dog that enjoys training is the one that is learning and learning well. It is easy to force a dog to be obedient, but it cannot be forced to enjoy it.

1.2 Association

The ultimate aim of police dog training is that a dog will react in the same way each time it hears a certain command or sees a visual sign from the handler. To obtain this degree of response from the dog, the handler must be consistent in commands and manner. The dog will not understand if there is day by day, a change in tone of command or a marked variation in attitude. From the day the dog is taken over, the same pattern of behaviour must always be followed. Consistency in command and action is of vital importance.

A dog rapidly learns to associate certain happenings with certain localities, sounds or people. If a particular criminal work exercise takes place too frequently in one location, the dog will anticipate what is required of it and control will suffer. It is for this reason that training must be carried out in a variety of localities and terrain, so that no particular area is allowed to become associated with any one exercise in the dog's mind.

1.3 Repetition

In the beginning of training, a dog is not aware of what is expected of it, nor how to associate words with the action required. As the mind of the adult dog has been compared with that of a child of 9 months, it is only natural that the dog will be uncertain of what it is to do. Before it can grasp the full meaning thoroughly and reliably, a command and its response will have to be repeated a number of times. Hence, repetition plays a big part in the correct training of a dog. It is essential that a dog is made to carry out the same command time after time until the required response is obtained without any delay. This repetition is far more important in training dogs than in the teaching of human beings. It is most important, however, that boredom is never allowed to creep in, either for dog or handler. After a few commands of 'sit' etc, it is far better to have a break or move on to another exercise. In teaching new exercises, the formula of Command, Action and Guidance is applied. This means that the dog is helped into the correct position when necessary but, as soon as it is expedient, the guidance must be withheld. In the early stages a dog should not be allowed to get into the wrong position, ie a wide or lazy 'sit', or 'down' instead of 'sit'. The dog must be corrected when it starts to do something wrong and should not be allowed to continue, but the exercise should be started over again. Care should be taken that the same mistake is not repeated. Play between exercises is just as necessary and important as training if a working happiness is to be obtained.

1.4 Commands

Commands must be given in such a way that they mean something to the dog. They must be given firmly and clearly, bearing in mind that the tone and sound of voice, not the volume, are the qualities that will influence the dog. In most cases, the more quietly the handler speaks the better, since the dog will pay more attention if spoken to in this way. Commands should not be repeated once the handler is satisfied that the dog knows their meaning, as this will lead to a bad association in the dog's mind. If a wrong command is given, no attempt should be made to correct it, as this will only tend to confuse the dog. Let the dog finish the first command, and then give him the command originally intended. Each time the dog executes the command correctly it should be rewarded with praise. It is at the discretion of the instructor as to the actual word of command for each particular exercise and be correctly applied.

1.5 Rewards

Whenever a dog successfully completes any action or command, however small, it must always be rewarded either physically, verbally or with food, or any combination thereof. This should be given even when the dog has had difficulty in doing the task but has accomplished it in the end. Praise can be given in various ways. Play at the end of each period of training has already been mentioned. This must be treated as of great importance and the praise for every small successful accomplishment must be given in such a manner as will suit the individual dog. The handler must find out what reward suits the dog and the amount to be given, and then apply it. After having been rewarded suitably, the dog will sense that it has done the right thing and will do it the more readily the next time it is given the same command. As has been stated, periods of training should end with a bout of play, but if the dog's performance in a particular exercise does not warrant praise it must be allowed to perform a short exercise it knows thoroughly, and does well, so that it will earn a reward legitimately. In this way, all training periods will finish on a happy note.

1.6 Correction

Dogs do not understand human standards or the principles of right from wrong. Rewards and correction are the means by which a dog can be taught what must be learned. If a dog does an exercise incorrectly, the exercise should never be allowed to go uncorrected. The handler should make the correction without losing their temper, help the dog to do the exercise correctly and then, when satisfactorily completed, give praise.

The simple admonishment of 'No', and the withholding of praise, will often be sufficient. If not, then correction may be more severe and effected by correct use of approved equipment and verbal commands (See Chapter 14). It must be understood that any correction must fit the particular dog, for all dogs are different, with varying temperaments and abilities. The correction should also relate to the incorrect behaviour and, equally important, that it must be well timed. A dog cannot associate correction with misbehaviour committed a long time before. It is vital therefore, that the correction must be administered immediately a dog misbehaves. The dog must never be corrected for slowness in learning or inability to understand. This will only spoil training and be counter productive.

Dog training is a continuous process, it doesn’t start and end on the training field, and physical contact between the dog and handler is a vital ingredient in the chemistry of producing a successful team. Physically praising a dog for correctly carrying out an exercise is just as important, even more perhaps, than other methods of reward. On the other hand, there may be occasions when another form of physical contact is warranted, such as encouraging the dog to sit or lie down. There may be times when the handler needs to attract the dog’s attention, and due to other distractions taking place in the immediate area, some form of physical contact may be necessary. This form of contact should be carried out as a means of reinforcing verbal commands, and as already stated, immediately the dog fails to carry out the command. The dog should always learn to feel secure in being close to it’s handler, and to regard the hands of it’s handler as symbols of praise and affection. Similarly, the training leash should never be used by the handler for striking a dog that misbehaves, for using it in this way will make the dog shy of the leash and lessen the effect of it when correctly and properly used.

All personnel involved in the training of police dogs are accountable in law, as stated in the Protection of Animals Act 1911, as amended (or equivalent Criminal Law or Statutory Law in Scotland) and no dog should ever be subjected to any cruelty during training, operational work or whilst in their care. The important criteria is that any chastisement must be reasonable and necessary, and in accordance with the law, making use only of approved equipment. (See Chapter 14 - Equipment).

Dogs possess the same basic senses as man. Four are
made use of in the training of police dogs.

2.1 Sense of smell

A dog's keenness of smell far surpasses that of a human being. A dog's nose is ideally adapted for the detection of the faintest odours. It is kept moist by glandular secretions and is extremely sensitive to the slightest air currents. When these currents are felt, a dog will turn his nose into them and sniff in order to test for any smell. During breathing, ordinary smells pass unnoticed as the olfactory organs lie above the current of air drawn through the nose, but if sniffing takes place, either because some odour is slightly sensed or because an external suggestion makes smelling desirable, the nostrils are expanded and the air is drawn upwards, so that the organs of smell are brought into full play. Studies have shown that dogs can respond to odour traces of all known sorts and in dilutions far more extreme than can be detected by man. Furthermore, they can distinguish between many odours which seem identical to human beings.

The subject of scent is dealt with in more detail in Chapter 3.

2.2 Sense of hearing

A dog's sense of hearing is so acute that it can hear sounds of a pitch far beyond the limit of those which can be heard by the human ear. However, it is in locating the origin of a sound that a dog shows great superiority over man, and it is this quality which is of most value in his work as a police dog. In utilising a dog's sense of hearing in training, it will be found that the pitch or tone of the voice, as well as the actual words, will affect the dog's response to oral commands.

2.3 Sense of vision

A dog's sight, when looking at stationary persons or objects, is poor compared to that of a normal human being. Nevertheless, the slightest movement, even at a great distance, will attract the dogs attention. This fact is of immense value in police work, provided the handler understands that their own range of horizon is much greater than the dog's, since the latter is limited by virtue of its height from the ground. Whilst it was thought that a dog sees everything in black and white and was unable to distinguish colours, that standpoint is being challenged.

2.4 Sense of touch

There is a wide variation among dogs in their responsiveness to the sense of touch. Some dogs are very susceptible to praise or correction; others appear to be relatively insensitive to it.

THE THEORY OF The Dog's Learning Process
How does a dog learn to carry out an action in response to a command given by a trainer? What are the factors that govern how quickly or accurately the dog learns to respond to such a command? Why are some dogs apparently difficult or impossible to train?

In order to understand the answer to these and other related questions, in an attempt to explain, from personal experiences, the way that we understand the way that a dog's mind works. The following information is taken from a serious study of police dog training and is not merely copies or extracts taken from reference books on animal behaviour and psychology.

Serious study into the learning behaviour of animals was pioneered by a Russian scientist called Ivan Pavlov. Pavlov carried out extensive research into our understanding of how animals learn. He found that by offering a dog some food (natural stimulus), an increase in the flow of gastric juices in the digestive tract was apparent (natural response). Further to this, he experimented by sounding a bell immediately prior to offering the dog food and observed that, after a number of repetitions, the sound of the bell alone (conditional stimulus) was enough to increase the production and flow of gastric juices (conditioned response).

Association is the basis of learning and in order for a dog (or other animal) to learn to carry out any action, the stimulus and the response must happen together. We associate thunder and lightning as one because they tend to happen closely together ie: the flash of the lightning followed by the roll of thunder. If the lightning flash followed ten days later by the clap of thunder, we may not guess that the two events are linked.

So for an association between two events to be linked, we must ensure that they happen together. In order to strengthen an association, we can use 'reinforcement'. This can be either positive (reward) or negative (correction).

Using the command 'sit' as an example, how does this fit together? We give the command 'sit' (conditioned stimulus) and immediately push the dog's rear onto the floor (conditioned response), and as soon as he is in the desired position we offer him praise (positive reinforcement). If the dog makes all the correct associations, in a short space of time the command 'sit' will make the dog respond by taking up the sit position in anticipation of the reward (praise).

3.1 Conditioned Stimulus

This is most commonly a particular word whose meaning is often descriptive of the action required by the dog eg: sit, down, come, etc. The word of command itself is unimportant as the dog has no recognition of meanings of individual words or sentences. Short words of command should be used whenever possible and they should all have an individual sound, in order to minimise the risk of the dog misinterpreting like sounding commands. A dog trained to associate the command 'No' with displeasure (negative reinforcement) may easily be confused if trained to carry out a send-away using the command 'go'. In this case a command of 'away' would be a better alternative as there is less risk of misunderstanding on the dog's part. The control of tone and pitch are essential when delivering commands, which is why one should not attempt to train the dog when in a bad mood. A person with a monotone voice would not generally be successful in training a dog to spoken commands. Compulsion commands trained by negative reinforcement (down, no, etc) are normally given in a low pitched tone, as the majority of dogs are reasonably submissive towards lower frequency noise. As an alternative to spoken commands, signals may be used. These are most commonly given by hand and can be just as successful as spoken commands, but have the disadvantage of having to be seen by the dog before they can be obeyed. It is not practical to train a dog to do 'a recall' to handler on a visual signal; if the dog is heading off in the opposite direction it will never know that it is being recalled, unless, of course, it looks round.

Although unnecessary, many handlers use a combination of commands and signals to transmit commands to their dogs. In training a dog to go into the down position the handler might use the command 'down' and simultaneously point to the ground. The only problem which may occur is in knowing which stimulus the dog is accepting - the command, the signal or a combination of both signal and command.

3.2 Conditioned Response

This varies from the simple act on the dog's part to a command of 'down' meaning, lie on the floor, to a more complex response which requires several different actions carried out in the correct order to a single command, such as 'seek' - meaning to go and use your nose to locate an article bearing a particular scent and indicate it's presence.

3.3 Association

This really is the 'key' to learning and the success of any dog training programme depends on the dog making all of the correct associations required in order to learn and carry out instructions from its handler.

As we have already seen, the timing between the command and the response required, is crucial if the dog is to make the correct associations in order to learn to carry out a command.

Using the "sit" command as an example, we will now examine all of the possible associations that the dog may have during the learning phase. The handler commences by walking the dog, in the park, on the lead, on their left hand side. At intervals the handler will stop and give the command "sit" and at the same time push the dog's croup (hindquarters) to the floor and reward it with praise. After many repetitions the 'dog' starts to respond to the command "sit" and no longer requires a hand on its croup to get it into the sit position.

A week of training goes by and sure enough the 'dog' will now sit every time it hears the command, and so we can pat ourselves on the back in the knowledge that the 'dog' understands the command "sit". Or does it? If we now let the 'dog' off the lead to run and exercise and when it is twenty yards away give the command "sit", the handler will find to their surprise that the 'dog' may not respond.

At home when the 'dog' is lying in front of the fire and we give the command 'sit' we find that it makes no attempt to get up into the sit position. On a visit to the local vet when we walk into the waiting room, sit on a chair, and give the command "sit", the dog again responds as though it does not understand what is required. A lot of people would say that the dog knows what is required but is being defiant, this is not the case. The dog really does not associate the command "sit" with the action of putting his rear on the floor. The association that the 'dog' has with the command is that whilst walking in the park at a particular spot on the handler's left side, on the lead, when the handler stops and gives a command "sit", the 'dog' is to put his rear on the ground. In the absence of any of the above associations the dog might well fail to understand the command. For example, walking the dog in a different park on the handler's right hand side or off the lead or giving the command "sit" whilst continuing to walk forward, the handler would probably find that the dog would not respond because the associations that he has with the command are limited to where the initial training took place.

So, in order to train the dog to understand the command of "sit" we must ensure that our training is structured to give the dog the experience to react to the command alone without regard to the environment and circumstances surrounding it. In other words, the command "sit" must be the primary association with the action required and we must work to eliminate, as far as possible, all of the secondary associations.

Some trainers may indeed think that they have trained their dogs to obey various commands but have, in fact, conditioned their dogs to a number of secondary associations. Heel free, for example, may require a check chain on the dog (not attached to a lead), which is jerked momentarily before walking forward, the handler may hold their left hand on their hip for the dog to be able to associate the fact that this is competitive heelwork - the command of "heel" being only of secondary importance. If the handler removes the chain or swings their left arm, even giving the command of "heel", the dog may not respond as effectively as when all the associations are correct. To emphasise the point, take a dog trained to respond to the commands "sit", "stand" and "down", either walking to heel or a short distance away from and facing the handler (distance control). Most people would believe that dogs trained to carry out these exercises for competition really do understand the commands. Most dogs, however, have picked up a string of secondary associations along the way. So in distance control for example, the handler, 1) positions the dog at a pre-determined point, real or imaginary and, 2) sets the dog up for the exercise by placing it in one of the three positions, 3) walks away from the dog a number of paces and then, 4) about turns and faces the dog and assumes a certain position with the body. We have already a set of 4 associations built into this exercise before the first command is given to tell the dog which position to adopt. Suppose the dog is left in the "sit" position and is waiting for the command telling it which new position to adopt, there are only two possibilities, stand or down - even a dog that does not fully understand the commands must get it right half of the time. It does not take much imagination to understand that once the dog is given all of the prior associations of the exercise by its handler then anybody, who the dog has never seen in its life before could come forward and command the dog to "sit", "stand" and "down" and the dog will respond. Let the same dog run in a field and then let the same person give the same commands and not surprisingly the handler may not get any reaction from the dog.

How about the retrieve? Does the dog really understand the command "fetch"? Think carefully about this one. The dog is put into the sit position, given a command to remain there, the article is thrown and the command "fetch" is given. Ninety-nine percent of trained dogs would still retrieve if the handler substituted the word "carrot" for fetch. All of the prior associations set the dog up for the act of retrieving; the article being thrown is usually the primary association.

It is also important that whichever commands are to be trained, the dog should be trained to obey them the first time it hears each of them. If we have a dog on a lead and tell it to "sit" four times before its rear touches the ground, we haven't taught it to sit on the fourth command, we had taught it to disobey the first three! If we need to shout commands to get a dog to respond when the dog is alongside us then what chance do we have of getting a dog to obey us when it is two hundred yards away.
Let us look at one of the commands in greater detail and the right and wrong way of using the voice. An area of difficulty many people experience is teaching the dog to hold something in its mouth. The dog is placed in the sit position and its mouth opened by pressing in its lips, just behind the canine teeth. As a retrieve article is placed in its mouth the command 'hold' is given in a soothing voice. After a few seconds the dog spits out the article and so the process is repeated. A few seconds later the article is again spat out and this time it is placed in the dog's mouth with a sharp command 'hold'. Out it comes again and it is put back in with a growled command of "HOLD IT". By now the dog has been subject to three completely different sounds made by its handler, all of which it is supposed to interpret as meaning the same thing, only by this time so much confusion and panic has set in that the dog is not receptive to learning at all. Now we have reached one of the fundamental theories of control - first control yourself.

It is much easier for the dog to understand what is required if the command is always given in the same tone. If it makes a mistake and for example drops the article then we use the command of negative reinforcement, simply "NO" given with the appropriate tone of voice. The verbal rebuke should be instant and SHORT followed immediately by the reinforcement of training progresses, so the dog's trust in his handler increases and so the bond strengthens. As both handler and dog progress, each new task that the dog is being taught becomes quicker and easier. Even the most complex exercise can be mastered as this confidence increases. When we talk about creativity in association with dogs, what we really mean is training the dog to become less inhibited by constraints of the more complex exercise and encourage the dog to be fairly flexible in its interpretation of a command or situation. We do not credit the dog with the ability to think out a situation in order to reach a conclusion. Also, with positive training, we are encouraging the dog to work towards a purposeful outcome and thereby increase the dog's drive or motivation to carry out a command. Some other points to consider regarding positive reinforcement training are:-

3.3.1 it is generally slower to teach than negative methods;

3.3.2 in certain exercises we might think that creativity is the opposite of what we want the dog to do;

3.3.3 it depends on the handler's ability to 'understand' their dog;

3.3.4 it requires a tremendous self control from the handler;

3.3.5 the reward needs to be available during all training sessions….
3.3.8 As training progresses the dog will learn to associate certain happenings with certain localities, sounds or people, and react accordingly. Whilst this type of association must be avoided at all costs in criminal work training, it is, conversely, the basis upon which rests the eventual standard of the obedience training. In this training the dog is expected to react in a set manner each time it hears or sees a specific command. To obtain this behaviour in a dog the commands, temperament and actions of the handler must always remain the same. Variations will only puzzle the dog and make training more difficult.

… The human has to make a conscious effort and sniff hard to savour an odour and get the air to pass over the Olfactory membrane. With the dog, each breath channels the air over the Olfactory Membrane, and the various odours in the air it breathes, register with every breath.

To a dog, following a line of scent which it wants to follow is as natural as eating, and it really needs no teaching, but you must induce it to follow a trail which although not necessarily of interest to it is of the utmost importance to you.


The biological differences between men and women make the odour of them different.

Personal Scent:

Personal odours can be identified to individuals dependant on their dietary and health regimes.
Different parts of the body each have their own odour armpits, feet, hands and so on.


The material from which the footwear is made; leather, rubber, canvas, suede etc: all smell different. This in addition to polish, cream, and other cleaners.-clcld have traced back to houde someone with same material shoes

Except for rubber all footwear is porous so the odour from the feet mingles with the smell of the footwear.


The different materials have individual smells, cotton, silk, wool, rayon etc: combining with washing agents. Whilst walking or running your clothing, rubs against itself causing particles to fall.


The occupational scent can be very distinctive:

Mechanic - Oil
Carpenter - Wood - Resin
Butcher - Meat - Offal
Baker - Bread - Flour

All clothing worn and footwear would be impregnated with the peculiar smells from his or her profession.

If all the individual, sex, personal scents, footwear, clothing and occupational scents are put together, the make up is very individual.

1.5 Factors Affecting Scent

Time, Coupled with exposure:

For moisture to evaporate, it must be exposed. If a bottle was filled with brandy and was corked, it would smell of brandy when re-opened, no matter how long it was left corked. If a little was spilled on the ground the smell would last only a few hours.

Time by itself does not destroy scent. Time coupled with exposure, which causes evaporation, does.

Sunlight or Heat:

Sunlight causes heat, heat causes evaporation.

The strength of the heat from the sun varies, the variations will alter its effect on the scent.

The higher the heat the greater the evaporation, therefore scent retention is minimal.

It is therefore important to consider what time of day tracking is taught.

Change of Temperature:

The rising of temperature dissipates scent, as the temperature rises so the scent rises it permeates with the air and then fades.

We do not need to see the sun for the temperature to rise.


Wind can be against us or assist us.

For the stronger the wind the quicker it disperses the rising ground scent. On the other hand wind will assist us in searching large areas for persons or property.


We have previously stated that there is no scent without moisture. However, heavy or prolonged rainfall after a track has been laid, will reduce the chance of a dog following it.

A light shower falling before the track is laid will greatly assist the dog to follow the trail of scent.

1.6 Changes of Terrain

Lush Vegetation:

This may help the dog in tracking because of its luxuriance there is more vegetation disturbed and damaged by a person walking or running.

Sparse Vegetation:

As you would expect, the scent retention on sparse vegetation compares unfavourably with that of lush vegetation. There is less shade so the sun can reach the moisture more easily. There is less vegetation to be disturbed by walking.


Forestry may afford good tracking. The ground retains moisture very well and the ground is shaded from the sun. The trees also break down the wind so the scent lasts well.

Rock, Tarmac and Concrete:

These surfaces make tracking difficult, scent may last for only a short time. There is very little moisture and very little ground disturbance when walked on. Heat from the sun evaporates any moisture quickly and the wind disperses the rising scent.

Generally speaking conditions are most favourable:

i) in mild, dull weather

ii) when the temperature of the ground is higher than the air, ie; normally at night time

iii) in areas where the ground is sheltered

Factors which aversely affect scent are:

i) hot sunshine

ii) strong winds

iii) heavy rainfall after the scent has been laid

Frost and snow may have the effect either of preserving of destroying a scent, depending on whether this occurs before or after the scent has been laid.

Pedestrian or vehicular traffic may disperse a scent.