Odour Imprinting in Detection Dogs: Are We Starting With Too Little?

Are We Starting With Too Little? Rethinking Odour Imprinting in Detection Dogs

Are we sometimes expecting our detection dogs to find an odour before we've properly taught them to recognise it?

It's a question I've been thinking about following a particularly interesting weekend delivering a two-day detection dog seminar in Essex.

Over the two days, I worked with 15 handlers and their dogs, all involved in nose work and scent detection at varying levels of experience. The seminar was brilliantly organised by Nikki from Turner & Pooch, and I thoroughly enjoyed working with everyone who attended.

However, something happened repeatedly throughout the weekend that got me thinking. Not just about the dogs and their training, but about how we introduce target odours, what we expect from our dogs and whether some of our established training practices deserve closer examination.

Before going any further, I want to make something absolutely clear.

This article is not a criticism of any of the handlers, their dogs or the people who have trained them.

In fact, it is as much about questioning my own thinking and expectations as an instructor as it is about anything I observed over the weekend.

I've been training and working dogs for more than 25 years, and one thing I've learnt is that experience should never prevent us from questioning what we do.

If anything, it should encourage us to question more.

The Odour: Napier Gun Oil

Throughout the weekend, the target odour was Napier Gun Oil, a substance commonly used within UK scent detection sports.

Although the handlers came from different training backgrounds, there was one particular similarity in how many of their dogs had been introduced to the target odour.

When I asked about their initial imprinting, the answers were remarkably consistent.

Most had used just one or two drops of gun oil.

The oil was generally applied to some form of absorbent material and subsequently placed inside a container, often a small metal magnetic tin or plastic tub.

These were then used to teach the dogs to locate and indicate the target odour.

During the weekend, the hides themselves varied in age. Some had been prepared around 30 minutes before searching, while others had been left overnight.

None of this was particularly unusual within the sport detection environment.

However, what interested me was how some of the dogs responded when searching.

Something Was Missing

Throughout the weekend, I observed several dogs actively searching areas containing the target odour, sometimes passing directly by the hide without displaying any obvious recognition.

What particularly interested me wasn't simply that a dog had missed a hide.

Dogs miss hides. That is nothing new.

What interested me was the apparent absence of a Change of Behaviour (COB).

For anyone unfamiliar with the terminology, a change of behaviour is the subtle or sometimes obvious alteration in a dog's behaviour when it encounters an odour of interest.

Depending on the individual dog, this might involve a change in breathing, head movement, search intensity, body language or a sudden attempt to investigate a particular area more closely.

As an instructor, I place considerable emphasis on recognising these behaviours because they can tell us a great deal about what a dog is experiencing during a search.

Yet, on several occasions, I saw dogs searching past the location of the target odour without any obvious change.

No noticeable increase in interest. No attempt to investigate. No apparent recognition.

Now, that doesn't automatically mean the dog couldn't recognise Napier Gun Oil.

We cannot assume that an odour was available to the dog simply because we knew where the hide was positioned.

But it did make me question something.

Had we adequately established odour recognition during the initial imprinting process?

Or were we expecting dogs to search for tiny quantities of an odour before we had sufficient evidence that they understood what they were looking for?

Are We Confusing Imprinting With Detection Thresholds?

This is where my thinking began to develop.

When I train operational detection dogs, my initial priority is to establish a clear understanding of the target odour.

I want the dog to learn that a particular odour has significance.

I want to see an observable response to that odour, and I want that recognition to become reliable before introducing unnecessary complexity.

Only then do I begin systematically developing the dog's ability to locate that odour in increasingly challenging circumstances.

This includes varying concealments, environments, odour availability and search complexity.

So why, I began asking myself, would we necessarily start a dog on just one or two drops of gun oil?

Is that the most effective way to establish initial odour recognition?

Or is it simply the way things have traditionally been done?

There is an important distinction between teaching a dog what an odour is and developing its ability to detect increasingly small amounts of available odour.

These are related, but they aren't exactly the same training objective.

My concern is whether we sometimes attempt to develop both simultaneously without first confirming that the foundations are sufficiently established.

An Example From My Own Training

When I initially started training whisky detection dogs, I was told from the outset that these dogs would eventually be required to locate trace and residual quantities of their target odour during live operational searches.

With that in mind, I didn't begin by introducing them to the smallest quantities they would ultimately be expected to detect.

Instead, I began imprinting the dogs on approximately 10 grams of the target material. Once I was satisfied that they recognised the odour, I progressively reduced the quantity, moving from 10 grams to 5 grams and continuing down until I was eventually training with just a single grain of the target material.

I then progressed to using items that had been exposed to the target odour, allowing the dogs to work with residual odour in an attempt to replicate, as closely as possible, the much lower levels of odour availability they would encounter during operational searches.

My approach was relatively straightforward.

First establish reliable odour recognition, then progressively develop the dog's ability to detect increasingly smaller quantities and more challenging presentations of that odour.

And that brings me back to my observations in Essex.

If we know that a dog will eventually be required to detect just one or two drops of gun oil, does that necessarily mean we should begin its imprinting with those same quantities?

What If We Started With More?

During the weekend, I began considering an alternative approach.

What if, rather than beginning with one or two drops of gun oil, we initially introduced the dog to a substantially larger source?

For example, what if we began with 50 ml or even 100 ml of gun oil in a suitable, safely contained training aid that allowed adequate odour release?

Would that provide a more accessible odour picture during the early stages of imprinting?

Could it make the initial recognition process clearer for the dog?

And once reliable recognition had been established, could we then systematically reduce the available odour until the dog was confidently detecting the much smaller quantities required for competition?

I want to emphasise that these quantities are suggestions for investigation, not proven recommendations.

I'm certainly not suggesting that every handler should immediately begin imprinting their dog using 100 ml of gun oil.

But I am suggesting that the question deserves consideration.

Why should the quantity of target odour we eventually expect a dog to detect necessarily dictate the quantity we use when first teaching that odour?

I think that's an important distinction.

More Oil Doesn't Necessarily Mean More Available Odour

Of course, there is another important consideration.

The quantity of a substance and the amount of odour actually available to the dog are not necessarily the same thing.

Odour availability can be influenced by numerous factors, including the volatility of a substance, exposed surface area, temperature, airflow, containment material and how the training aid has been prepared.

A large quantity of oil inside a tightly sealed container may release less accessible odour than a much smaller quantity presented on an exposed absorbent material.

Equally, a freshly prepared hide may behave differently from one that has been left for several hours.

So simply increasing the volume of gun oil is not guaranteed to produce the result I'm considering.

What matters is what actually reaches the dog's nose.

And that is precisely why I think we need to examine our imprinting methods more carefully rather than simply assuming that increasing or decreasing the amount of material will produce a predictable result.

Recognition Must Come Before Expectation

Something I regularly emphasise in my training is that we must understand what the dog has actually learnt, rather than what we believe we've taught it.

There can be a considerable difference.

A dog that successfully locates a training aid several times during imprinting has not necessarily demonstrated robust odour recognition across different environments, presentations and concentrations.

It may have learnt the exercise. It may be responding to contextual information.

It may have developed expectations based on how the training has been presented.

Or it may genuinely recognise the target odour but have limited experience of how that odour presents under different conditions.

These possibilities are not always easy to separate.

That's why I believe we need to look beyond whether a dog successfully indicates a hide and consider the behaviours leading up to that indication.

Is the dog demonstrating genuine recognition?

Is it independently investigating the odour?

Can it recognise that same target when the presentation changes?

And perhaps most importantly, what happens when the dog searches an area containing the target odour and shows no apparent recognition whatsoever?

Do we automatically assume the search was too difficult?

Do we blame distraction?

Do we assume the dog wasn't sufficiently motivated?

Or should we sometimes return to the very beginning and examine the quality of our initial odour imprinting?

What Does the Research Tell Us?

There is scientific research that makes this discussion particularly interesting.

Research into canine detection thresholds has demonstrated that dogs trained with systematically varied odour concentrations can improve their ability to detect lower concentrations.

One study involving 11 dogs found that those receiving additional training with progressively lower concentrations performed significantly better on subsequent low-concentration detection tests than dogs continuing to train at the original concentration.

This is particularly relevant because it demonstrates that the ability to detect very low concentrations should not necessarily be assumed simply because a dog recognises the same odour at a higher concentration.

Research into odour availability has also highlighted how factors such as containment, temperature, surface area and the characteristics of the target substance influence the amount of odour available to a dog.

These findings reinforce the importance of managing odour availability throughout training.

However, they do not establish that imprinting with 50 or 100 ml of Napier Gun Oil is superior to imprinting with one or two drops.

That particular question would require controlled comparisons.

Nevertheless, the research gives us good reason to examine how we establish odour recognition and subsequently develop sensitivity across a range of conditions.

Are Our Expectations Sometimes Too High?

Another thing I reflected upon during the weekend was the expectations we place on our dogs.

We can sometimes forget just how much we are asking them to do.

We introduce a target odour, teach an indication, develop a search pattern and then expect the dog to locate that odour in unfamiliar environments, often concealed in increasingly difficult locations.

And when something goes wrong, our attention frequently turns towards the dog's search behaviour or indication.

But perhaps we should sometimes be looking further back.

Perhaps the problem isn't the search.

Perhaps it isn't the indication.

Perhaps the foundation of odour recognition isn't quite as secure as we believe it is.

This is not to suggest that every missed hide is the result of inadequate imprinting.

Far from it.

Dogs can miss hides for many reasons, including odour movement, accessibility, environmental conditions, training history and handler influence.

But I do believe that odour recognition should be one of the first things we investigate when a dog repeatedly searches past a target without any observable change of behaviour.

Rather than making the exercise more complicated, perhaps we should make the question we're asking the dog clearer.

What Would I Like to Investigate?

Following this weekend, I'd be interested in comparing different approaches to initial gun oil imprinting.

For example, taking dogs with no previous exposure to the target odour and introducing them using different quantities and presentations of gun oil under controlled conditions.

I'd want to examine how quickly reliable recognition develops, whether dogs demonstrate consistent changes of behaviour and how well that recognition transfers to different quantities, containers and environments.

I'd also want to establish whether a larger initial source offers any meaningful advantage, or whether other factors, such as exposed surface area and presentation, are more important.

Ultimately, the question isn't whether one drop, ten drops or 100 ml is the correct answer.

The question is whether we're choosing our imprinting methods because we understand how effectively they establish odour recognition, or simply because those methods have become accepted practice.

And I think that's worth investigating.

The Importance of Continuing to Learn

One of the reasons I enjoy delivering seminars is that they challenge my own thinking.

I don't attend these weekends believing that I have all the answers.

Despite more than 25 years of training and working dogs, I continue to encounter situations that make me reconsider how I approach training.

This weekend was a perfect example.

Fifteen handlers, different dogs, different experiences and one common target odour.

And from those two days came a question that I hadn't previously given enough consideration to.

That's what good training environments should encourage.

Observation. Discussion. Questioning.

And occasionally challenging ideas that we've accepted for years.

I want to thank everyone who attended the seminar in Essex and particularly Nikki from Turner & Pooch for organising such an enjoyable weekend.

The handlers and their dogs gave me plenty to think about, and I hope my observations give others something to think about too.

Because ultimately, whether we're training dogs for sport or operational deployment, I believe we all share the same objective.

To develop dogs that genuinely understand their task, recognise their target odour and can demonstrate that understanding reliably and independently.

And perhaps sometimes, before asking our dogs to find less, we should be asking ourselves whether we've taught them enough.

References and Acknowledgements

The observations, opinions and training experiences discussed in this article are my own. However, the wider discussion regarding odour recognition, detection thresholds and odour availability is informed by published scientific research.

Scientific References

1. DeChant, M. T. & Hall, N. J. (2021). Training with varying odor concentrations: implications for odor detection thresholds in canines. Animal Cognition, 24, 889–896.
   https://doi.org/10.1007/s10071-021-01484-6

2. Sloan, K. B., Maughan, M. N., Sharpes, C. E., Greubel, R. R., Gallegos, S. F., Miklos, A. E. & Waldrop, L. D. (2025). The manipulation of odor availability of training aids used in detection canine training. Frontiers in Allergy, 5, 1445570.
   https://doi.org/10.3389/falgy.2024.1445570

3. Scentwork UK. Target Odours and Preparation Guidance.
   https://scentworkuk.com/swuk-odours/

Acknowledgements

My thanks to Nikki from Turner & Pooch for organising the two-day detection dog seminar in Essex, and to all 15 handlers who attended with their dogs.

Their participation, questions and willingness to engage in training exercises provided the observations that prompted this article.

As always, the opportunity to work with different dogs and handlers continues to challenge my own thinking and encourages me to examine established training methods.

The questions raised in this article are intended to encourage discussion and further investigation, rather than present any particular imprinting method as scientifically proven to be superior.