False Positive Indications? STOP! You have a Scent Detecting TRAINING problem!

Delphi indicating CORRECTLY on her target scent source!

A false positive indication is one where your dog indicates, or alerts, on something that is NOT her target scent source (Lehnert and Weeks, 2016). To all intents and purposes, it looks as though she’s correctly located the target odour but … she hasn’t! You’ve been misinformed.

At Scent : Detect : Find Ltd, false positive indications are an extremely rare occurrence. If they do happen, they’re easy to identify and quick to remedy. In large part this is because …

a) All dogs are trained to perform a highly reliable, passive indication with duration – a sustained nose touch, or point. This indication is easy to distinguish from any passing investigatory sniff – which the handler can confidently ignore. In contrast, the correct indication is clear and unambiguous and is always generously rewarded.

b) Importantly, all training is broken down – split – into its, tiny, constituent parts rather than being lumped together into one, large, unmanageable whole (Berg, 2018. Zerubavel, 1996). Splitting allows any training difficulties to be addressed immediately, including any false positive indications, before the problem has the chance to escalate further or become entrenched.

If you’d like to know a little more about Splitting and Lumping, simply follow this link to one of my previous Blog Posts – Smoothing out the Lumpy Bits; Why it might be wise to teach the indication before the search and all that back chaining stuff.

Strangely, false positive indications seem to be an accepted part of Scent Detecting practice – “Just one of those things“. “Nothing to worry about“. “To be expected“. “Par for the course“. “It happens“.

Well, I’m here to tell you otherwise …

False positive indications are not just one of those things.

False positive indications are something to “worry” about.

False positive indications should never be an expected, or usual, part of Scent Detecting training or practice.

False positive indications are a symptom of one, or more, Scent Detecting training problems which need to be addressed rather than accepted!


What are the likely problems with false positive indications? 

Well, if you’re “just having a bit of fun” with your dog, perhaps a false positive indication doesn’t matter too much to you. That said, it’s worth asking yourself why “just having a bit of fun” is any less deserving of careful training than any other activity you choose to participate in? Would you only half train a Sit? Are you happy with a Recall that only happens sometimes? Is it OK for your dog to choose her own route around an Agility Course? …

A dog who doesn’t understand what’s required of her, who hasn’t benefitted from careful guidance, who gets rewarded on some occasions but not on others (dependent on her handler’s whimsy on a particular day) … well … that’s NOT a dog who’s having “fun“. It’s far more likely that she’s confused and anxious. If you want to use Scent Detecting as a fun activity for your dog, there are plenty of ways to achieve this including scent trails, scatter feeding, treat searches, hiding toys and using Scent ‘n Snack mats. These type of scent-based activities can provide numerous behavioural benefits for your dog and require little, if any, training – your dog is a natural scavenger and comes pre-programmed to locate food!

If you’d like some more ideas on how to entertain your dog’s nose, look out for one of my next Blog Posts – Scent-Based Nose Games – Just a bit of fun!

In contrast, if you’re the handler of a working dog, or take part in competition style Scent Detecting, then the reliability of your dog is key to your success. Be under no illusion, a dog who gives false positive indications is an unreliable Scent Detecting dog. If you cannot trust her indication you’ll only know if she’s correct if you can see the target scent source yourself or watched where it was hidden at some earlier point in time. When faced with a truly blind search – one where the location of the target scent source is unknown to you – well … I wish you all the luck in the world!


What are the potential causes of false positive indications?

There can be numerous potential causes for false positive indications but, very sadly, the vast majority are handler and training related. The root cause of your problems may be just one, very particular, issue or could be the result of a combination of different issues. 


  1. Contamination / Residual Odour

This is probably the number one rationale offered by handlers to “explain” away their dog’s false positive indication – “The area must have been contaminated”. “The scent wasn’t handled correctly”. “My dog’s nose is just so good that she picks up on every little bit of residual odour”. Sound familiar? Well, what if I were to tell you that although a contaminated search area is a real thing – it does happen and it happens all the time – the root cause of your problem is not odour related, it’s training and handler related? 

Your dog is what’s referred to as a macrosmat or, ‘keen smeller’. Her olfactory threshold, the level at which she can first start to detect an odour, is reportedly as low as 2 – 3 parts per billion (ppb) and, quite possibly, for some odours, as low as 2 – 3 parts per trillion (ppt) (Helton, 2009). Given this incredible degree of sensitivity to odour, it seems a little surprising that your dog doesn’t give you a false positive indication more often than she does. So, what’s going on?

As an aside, keep in mind that if your dog indicates on any residual odour or contaminated area, she’s actually correct! It isn’t a false positive indication. What she’s doing is indicating on a very low concentration of the target odour … something you may not have wanted or planned … nevertheless, your dog is correct. For clarity, I consider residual odour to be any odour “left behind” by the target odour source when it has been removed from a search area or container. In contrast, contamination occurs when the target odour source leaves a residual odour in an otherwise “clean” area or when the target odour source becomes contaminated itself by another odour. Given the “catch all” nature of the definition of contamination, this is what I’ll be referring to throughout the following discussion.

As Gadbois (2016) has pointed out, your dog’s olfactory abilities are so good that no amount of cleaning, or careful handling of the target scent source, or use of gloves, will reduce contamination sufficiently for her not to be able to detect it. In addition, those gloves that you’ve been advised to wear are a recognised contaminant in themselves (Learning Centre Valutek Blog, 2016). Dogs whose handlers use Nitrile gloves have been found to indicate on anything that the gloves have come into contact with! By now you’re probably starting to appreciate that, to a very large extent, attempting to avoid contamination is a waste of your time. Far better to acknowledge that contamination is a real issue and work with it.  

Scent : Detect : Find Ltd adopts a number of different strategies to overcome any so-called false positive indications as a result of odour contamination. 

1. Initial training is conducted using a large concentration of target odour

Dogs are rewarded generously for indicating the location of this “large” odour source. Although they are likely to notice contaminated areas in their search environment – dogs may hesitate and investigate areas of the room where the scent source has previously been – importantly, they aren’t rewarded for this behaviour. It doesn’t pay off. In short, they’re learning to ignore any contamination as they discriminate between the different concentrations of odour. Dogs will work with this highly concentrated odour source until they’ve gained considerably more experience. At this point, the odour concentration will be reduced – Diminished or Diluted

Interestingly, according to Laing et al (2003.), a “change in concentration can actually modify the quality of  … [an] … odor“. As Wilson et al (2006) point out, “for many odours, as the concentration increases, the perceived quality of the odour changes“. With this in mind, Goldblatt et al (2009) suggest that Scent Detecting dogs should be “trained and maintained on a range of intensities of [odours] that they may encounter in [their Scent Detecting work]”. 

A recent pilot study by DeChant et al (2021), investigating the ability of dogs to both generalise across, and discriminate between, different odour concentrations, has provided further support for Scent : Detect : Find Ltd’s training approach to odour concentration. As described previously, all dogs begin their training with a very high concentration of their target odour and only after some considerable amount of Scent Detecting experience are they then introduced to the same target odour at much lower concentrations. This approach applies to all target odours used. 

According to DeChant et al (2021), “dogs can be trained to actively not respond to concentrations of a trained odorant below a desired threshold“. Put simply, your dog can be trained to ignore contaminated search areas. In DeChant et als (2021) study, “false alarms decreased after Concentration Discrimination training. This may result from training dogs not to respond to the low, but detectable concentration odor”. Clearly, on this account, false positive indications cannot be attributed to issues of contamination. There’s a definite need to examine the training protocols in use and pro-actively train using varying concentrations of odorant.   

2. On locating their target odour, all dogs are trained to give an unambiguous passive indication with duration

As already discussed, all dogs at Scent : Detect : Find Ltd begin their training by working with a large concentration of target odour. This is what they learn to indicate, or alert, on. I favour the passive indication and train my own, and other handlers, dogs to place their nose as close to the target scent source as possible and hold it there for a minimum of 5 seconds or until their handler asks them to move away. There can be no mistaking the precise location of the target odour source when the dog’s nose is either touching or pointing toward it. Adding duration to the indication adds even more certainty. A passive indication with duration allows the handler to “ignore” any small acknowledgements of contamination within a search area and simply wait for the added commitment – the duration – that comes when the dog is convinced that she’s located the highly concentrated target odour source. The dog is free to check out all areas of possible contamination because the handler can be confident that once investigated, she’ll dismiss these contaminated areas and move on. 

Recently, I’ve noticed a growing trend toward relying on a dog’s change of behaviour (COB) to help the handler recognise that their dog has located the target scent source. Typical changes in behaviour might include slowing down, speeding up, heightened interest in a particular area of a room, walking on tip-toes with head held high … the list of possibilities is almost endless. Each of these behaviours may help you narrow down the location of the target scent source but may also act to totally mislead you. The dog may simply be checking out an area of contamination.

For further discussion of indications, you might like to follow this link to one of my previous Blog Posts – The Indication. It’s not an optional extra.

3. In very specific circumstances, it’s worth taking care to avoid any possible contamination

Although, generally, I don’t worry about contamination, there are a couple of very specific circumstances where target odour handling needs to be a little more thoughtful.

a) Storage – Keep your target odour in the most secure container you can get your hands on. Your dog needs “down-time”. Remember, if you’ve taken the time to familiarise your dog to the target odour it will have become a “motivational magnet” for her. If she can detect the odour she’ll be in “work mode”. Give her a break!

b) Frequently used containers – If you’re likely to use a particular container on repeated occasions, make sure you can identify it – label it in some way – and only use it to hold the target odour. Frequent contact with the target odour source will, over time, result in a heavily contaminated container closely matching the concentration of the target odour source itself.  


2. Handler Pressure and the Clever Hans Phenomenon

As Galambos et al (2021) point out, “dogs are unmatched amongst non-human animals regarding their inter-species social skills … thousands of years of domestication [have] enabled them to excel at the reading of and responding to human social-communication signals” … and here lies the problem … our dogs, and their performance, are affected by us! 

Two potential Scent Detecting problems arise from this.

1. Our dogs will be aware of our mood and emotions and respond accordingly

As Galambos et al (2021) states, our dogs have a “human-like susceptibility to social influence” and demonstrate a “spectacular level of social sensitivity“. This is likely to be a particular problem within competition-style Scent Detecting circles where handlers can place enormous “pressure” on themselves to do well and gain rosettes. Unintentionally, the handler’s “pressure” is then “transmitted” to their dog.   

Scent Detecting videos, available freely on various social media platforms, are well worth checking out. Make your focus of attention the dog and his body language rather than the actual Scent Detecting task itself. Watch for any Calming Signals (Rugaas, 2006) – lip-licking, yawning, turning away from the task, hesitancy, slowing down – and link these behaviours to the handling skills that you observe. Mariti et al (2017) consider these signals as having “a communicative role” – they can help you identify how your dog is feeling. More often than not, this will be a reflection of how you’re feeling! Custance and Mayer (2012) refer to this phenomenon as “emotional contagion“. 

And the consequences for your dog’s Scent Detecting performance? If she’s becoming uncomfortable in the search area because of the way you’re feeling and the demands you may be placing on her, the quickest way to end the experience is … you guessed it … to indicate. Unfortunately, more often than not, this will be a false positive indication. Again, without a doubt, this is reflective of a training issue. Are you and your dog ready for this Scent Detecting challenge? Have you put in the necessary preparatory work? Do you both have the requisite level of experience? Do the expectations you have of your dog’s performance outstrip their current level of ability?

2. The Clever Hans Phenomenon

The Clever Hans Phenomenon, or Clever Hans Effect, refers to any situation where a person or animal can be influenced by the subtle and unintentional cueing of another (Jackson, 2005). Your dog is able to recognise and respond to the cues delivered by those around her … including you, her handler! Problems arise when those cues misinform her. Importantly here, cues that misinform her about the location of the target scent source resulting in a false positive indication.

In a study by Szetei and Miklosi (2003), almost 50% of the study dogs would go to an empty bowl indicated to them by a person pointing at it rather than to a bowl in which the dog had previously seen and smelt food! The dogs appeared to place greater weight on the human cues than their own senses and experience.

In another study by Lit et al (2011), 18 drug / explosive detection dog and handler teams were given a number of detection tasks to complete. None of the tasks contained drug / explosive scent. In other words, they were all blank searches. Any alerts / indications that the dogs gave would be incorrect; false positive indications. Two of the detection tasks included a small piece of paper that falsely marked a scent location and two other detection tasks contained a decoy scent (toy / food).

In the detection tasks that included the false paper markers the handlers reported that their dogs alerted more at the marked locations than in other parts of the search area. According to Lit and her co-authors, when the handlers believed that there was scent present in the search area (paper markers) they were more inclined to claim that their dogs had indicated on a target scent; a false positive indication. As Lit et al (2011) state, this would seem to confirm that “handler beliefs affect outcomes of scent detection dog deployments“.

As Udell et al (2010) point out, with “increasing evidence for an acute sensitivity to human gestures and attentional states“, guarding against the Clever Hans Phenomenon in our dogs can be highly problematic but an essential consideration in the development of a reliable scent detecting dog. Again, any false positive indication in these circumstances is a training issue rather than simply “one of those things“. Suggestions for reducing the Clever Hans Effect include;

Practice more blind searches – If you don’t know where the target scent source is located you’re less likely to influence your dog.

Keep an OPEN mind – Try not to “second-guess” where the target scent source might, or might not, be. Chances are you’ll be wrong and, in the process, misinform your dog resulting in a false positive indication.

Allow your dog to work independently – Giving your dog the space and freedom to work by herself helps to reduce any tendency she might have to watch for cues from you rather than search the environment carefully herself. If you start to show interest in a particular part of the search area it’s highly likely that your dog will too. As soon as this happens, believing that your dog has located the target scent source, you’ll start to look harder yourself. A vicious circle with the almost inevitable result – a false positive indication from your dog prompted by inadvertent cues from you. 

Beware of your audience – Keep in mind that your dog will be sensitive to cues from your audience as well as from you, her handler. Encouraging your audience to talk to one another can be helpful here. The more attention they’re giving one another the less attention they’ll be paying to your dog as she searches the area. Be particularly alert to ‘audience silence’ and ‘breath-holding’ as your dog comes close to her target scent source. Without a doubt, your dog will notice it even if you don’t!

Want to know more about this subject? Just follow this link to False indications, Clever Hans and You.


3. Target Odour is not a “Motivational Magnet” for your dog

Familiarising your dog to the target odour refers to the process of Classical or Pavlovian conditioning that helps her form positive associations with the scent. What starts out as a completely irrelevant odour, something that your dog would not normally be attracted to, will, after conditioning, start to become highly relevant. The presence of the odour will predict that good things will follow. According to Hall et al (2014), the process of familiarisation enhances odour discrimination training and can reduce overall training time.

During the familiarisation process the target scent becomes what Berridge et al (2009) describe as a “motivational magnet” – something that has to be approached, often compulsively. This fits well with the notion of “scent obedience” – the idea that the target scent itself will act as a cue to your dog to search it out and stay with it. 

For more information on the odour familiarisation process, you might like to follow this link to Smoothing out the Lumpy Bits: Why it might be wise to teach the indication before the search and all that back chaining stuff .  

Self-evidently, if the target odour is not important to your dog – if you haven’t turned it into a motivational magnet for her – then she has no real reason to search it out or indicate to you that she has found it. Pair this situation with a reliance on a change in your dog’s behaviour (COB) – rather than a fully trained indication – to show you where the target odour might be located and you have the recipe for a Scent Detecting disaster. To clarify, any passing sniff at the “olfactory messages” left by another dog, or the odour of food crumbs dropped on the floor, will look like (and is) a COB and, as such, will be considered an indication. Unfortunately, it’s a false positive indication. 

The simple take-home message – review your training. Take the time to familiarise your dog to the target odour and train a reliable, unambiguous, indication!


4. Your dog has not learnt what you thought you had taught her

Recently, I came across a video clip of a dog working a “Line-Up” comprising a number of identical containers. Apart from considerable hesitancy on the dog’s part to both start, and continue, working (which points strongly to issues of Handler Pressure and Incomplete / Inadequate Training), it was very obvious that the dog did not fully understand the task in hand. On approaching the Line-Up, the dog gave false positive indications on multiple containers before, eventually, arriving at the correct container – the one that actually held the target odour source. If the handler had not placed the target scent source there herself, her dog’s multiple false positive indications would have completely misled her. Unfortunately, on the evidence provided by this video clip, this is an unreliable Scent Detecting dog.  

Although this type of issue can become evident during many different types of Scent Detecting challenge, it’s probably most obviously identifiable in Line-Up tasks. In this particular case, the handler obviously believed she had taught her dog to deliver a passive indication, with duration, when she located the target scent source. In reality, her dog had learnt to deliver a passive indication, with duration, when it encountered any of the containers. The dog had learnt a visual cue – the containers – rather than the intended target odour cue. 

Again, in common with other false positive indicationsthis is a training issue. One that needs to be addressed by the handler if her dog is to progress any further.  

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Frodo CORRECTLY identifying the location of his target odour source in a Line-Up Scent Detecting Task

5. Incomplete / Inadequate Training

A few things to consider when training your dog …

1. Do you have a plan?

Do you have a clear picture of what you want to achieve? Have you thought about the steps you might need to take to achieve this end goal? Do you have realistic expectations of just how long this goal might take to achieve? Have you assessed your dog’s current level of ability and used this as the starting point for your training? Are you prepared to take one, or, possibly more steps back in your training plan to ensure that any new training is building on firm foundations? Have you considered your dog’s current level of health, fitness and emotional well-being? Have you considered how long your training sessions should be to optimise learning? What about rewards? Is your training plan Evidence Based? Without a doubt, these are only some of the questions you should ask yourself before starting to formulate your training plan or schedule. 

2. Have you split your training?

As discussed earlier, when it comes to Scent Detecting training, I’m a big advocate of splitting rather than lumping. Splitting requires you to break your training down into tiny, incremental, steps. Speed of progress is dictated by your dog rather than any pre-determined time-frame decided by you, her handler. This forces you to consider your dog’s understanding of the particular training task in hand, and her ability to perform the element reliably, before attempting to move on with your training. If you move on too quickly, poor understanding, or performance, of a particular training element will result in false positive indications as your dog struggles to work out what is expected of her.  

3. Are you training or testing?

If you ever find yourself saying something like, “let’s just see if she can do this” then it’s highly likely that you’re testing your dog rather than training her. If your dog does happen to succeed at some challenge you’ve set her, this will have far more to do with luck than any carefully considered application of training skills on your part. Why should that matter? Well, it matters because, next time, your luck might just run out. As the saying goes, “It takes more than one Swallow to make a Summer” and it takes more than one lucky success to make a RELIABLE Scent Detecting dog. 


and in conclusion …

False positive indications should never be an accepted part of Scent Detecting practice. Without a doubt, the most likely culprit will be a training issue. If you want a reliable Scent Detecting dog … STOP. ANALYSE and ADDRESS the issues even if that requires you taking many steps back in your training.  


Final Note

As with all of my blogs, I include a reference list. This allows you to investigate the topic a little further, check out the sources of my information and decide for yourself whether my interpretations of the literature are an accurate reflection of the author’s work. Happy reading.

© Scent : Detect : Find Ltd – 2021


References / Further Reading

  1. Berg J (2018) Lumping and splitting. Science. 359. 6382. 1309
  2. Berridge KC, Robinson TE and Aldridge JW (2009) Dissecting components of reward; ‘Liking’, ‘Wanting’ and Learning’. Current Opinion in Pharmacology. Feb. 9(1): 65-73
  3. DeChant MT, Bunker PC and Hall NJ (2021) Stimulus Control of Odorant Concentration: Pilot Study of Generalization and Discrimination of Odor Concentration in Canines. Animals. 11. 362
  4. Custance D and Mayer J (2012) Empathic-like responding by domestic dogs (Canis familiaris) to distress in humans; An exploratory study. Animal Cognition. September. Vol 15. Issue 5. 851-859.
  5. Gadbois S (2016) Modern Dog Training and Science: Are We Doing it Right? Common Misconceptions and Pitfalls. The Science of Sniffer Dogs. Oxford: Two Day Conference
  6. Galambos A, Gergely A, Kovacs AB and Topal J (2021) Affect Matters: positive and negative social stimulation influences dogs’ behaviour in a subsequent situation involving an out-of-reach object. Applied Animal Behaviour Science. Journal Pre-Proof
  7. Goldblatt A, Gazit I and Terkel J (2009) Olfaction and Explosive Detector Dogs. IN: Helton WS (Ed) Canine Ergonomics. The Science of Working Dogs. London: Taylor and Francis Group
  8. Hall NJ, Smith DW and Wynne CDL (2014) Effect of odor pre-exposure on acquisition of an odor discrimination in dogs. Learning and Behavior. Jan
  9. Helton WS (2009) Overview of Scent Detection Work. Issues and Opportunities. IN: Helton WS (Ed) Canine Ergonomics. The Science of Working Dogs. London: Taylor and Francis Group
  10. Jackson J (2005) The Clever Hans effect – a horse’s tale. Critical Thinking. http://www.critical-thinking.org.uk/pdf/clever-hans.pdf
  11. Laing DG, Legha PK, Jinks AL and Hutchinson I (2003) Relationship between molecular structure, concentration and odor qualities of oxygenated aliphatic molecules. Chemical Senses. 28. 57-69
  12. Learning Centre Valutek Blog (2016) Odor and Color Determine the Quality of Your Cleanroom Gloves. https://blog.valutek.com/home/odor-color-determine-the=quality-of-your-cleanroom-gloves# Accessed: 27.8.2020
  13. Lehnert M P and Weeks E N I (2016) Trained Dogs in Insect Detection. IN: Jezierski T, Ensminger J and Papet L E (Eds) Canine Olfaction Science and Law. Advances in Forensic Science, Medicine, Conservation, and Environmental Remediation. London: Taylor and Francis Group.
  14. Lit L, Schweitzer JB and Oberbauer AM (2011) Handler beliefs affect scent detection dog outcomes. Animal Cognition. 14: 387-394
  15. Mariti C, Falaschi C, Zilocchi M, Fatjo J, Sighieri C, Ogi A and Gazzano A (2017) Analysis of the intraspecific visual communication in the domestic dog (Canis familiaris): a pilot study on the case of calming signals. Journal of Veterinary Behavior Clinical Applications and Research. Volume 18. March-April. 49-55.
  16. Rugaas T (2006) On Talking Terms with Dogs: Calming Signals. 2nd Ed. Washington: Dogwise Publishing
  17. Szeiti V and Miklosi A (2003) When dogs seem to lose their nose: an investigation on the use of visual and olfactory cues in communicative context between dog and owner. Applied Animal Behaviour Science. Sept 5. Vol 83. Issue 2. 141-152
  18. Udell MAR, Dorey NR and Wynne CDL (2010) What did domestication do to dogs? A new account of dogs’ sensitivity to human actions. Biological Reviews. 85. 327-345
  19. Wilson DA and Stevenson RJ (2006) Learning to Smell. Olfactory Perception from Neurobiology to Behavior. Baltimore: The Johns Hopkins University Press
  20. Zerubavel E (1996) Lumping and Splitting: Notes on Social Classification. Sociological Forum. 11.3. 421-423.

 

 

So you think your dog is detecting the odour of mobile phones …

Discovering which chemicals might be involved in the manufacture of mobile phones can be a surprisingly difficult task. According to Compound Interest (2014), “there’s actually remarkably little easily accessible information out there that details the specific compounds used” and even less information regarding any associated odours.

That said, there seems little doubt that mobile phones “smell” – our dogs can find them – but what odour, or odours, are they actually latching on to? What produces the odour that is significant to our dogs? Possibilities include chemicals associated with the phone’s memory chip, touchscreen and rechargeable lithium ion battery and probably a lot else besides.


Memory Chip

Triphenylphosphine oxide – a flame retardant used to protect the memory chips in electronic devices including memory sticks, hard drives, SD cards and mobile phones.

Touchscreen

Lithium Niobate used in surface acoustic wave (SAW) devices. These convert electric signals to acoustic waves.

Lithium Ion Battery

Dimethyl Carbonate – produces an alcohol-like odour.

Diethyl Carbonate – has a nail-polish-like odour.

Lithium Niobate – used in electrodes of the lithium ion battery.


But how do we know whether our dogs are using any of these chemicals to find mobile phones?

A few months ago, one of my client’s reported that her dog, without any specific training, was able to locate hidden memory sticks. The client had discovered this ‘natural talent’ a few weeks previously when she’d asked her dog to find another, already trained, odour source. Instead, her dog found a memory stick that, earlier in the day, had been hidden for another dog!

Abel locating a mobile phone – But what odour, or odours, are significant to him?

So, was this evidence that her dog was searching for memory stick odour – perhaps one, or more, of the chemicals listed previously – or was there something else going on?

Given that her dog had received no previous Scent Detecting training with memory sticks – there had been no familiarisation process – and that memory stick odour is unlikely to be an Unconditioned Stimulus (UCS) for any dog (as far as I’m aware, no dog is naturally attracted to memory stick odour), it seems highly unlikely that her dog was locating memory sticks because of their very specific, chemical, profile and associated odour.

If you’d like to know a little bit more about the familiarisation process and unconditioned stimuli, take a trip over to one of my previous Blog posts, Smoothing out the Lumpy Bits; Why it might be wise to teach the indication before the search and all that back chaining stuff.

So, what was going on?


The simplest explanation is usually the correct one

During the 12th Century, a Franciscan friar – William of Ockham – argued that “the simplest answer – that is, the answer that requires the fewest assumptions – is generally the correct one” (Salter, ?date). “Ockham’s Razor”, as it has become known, or the “Law of Parsimony”, is the view that “of any given set of explanations for an event occurring, the simplest one is most likely the correct one … [it] is a vital tool in rigorous thought. By reducing the number of unsupported assumptions in an explanation, you reduce the likelihood of being wrong” (Salter, ?date).

So, rather than my client’s dog demonstrating some sort of ‘natural’, or ‘super-natural’, Scent Detecting ability, might there be a simpler, more straightforward, explanation? An explanation that fits better with the current knowledge of odour, olfaction and learning?


Contamination

Rather than being an example of ‘natural talent’ at work, the simplest explanation for this dog’s apparent ability to locate memory sticks (with no previous training) is provided by … contamination. In all likelihood, the memory stick had been contaminated with an odour that the dog had previously been trained to detect alongside human scent and, if they were used, the odour of gloves. Yes, those gloves you’ve been told to wear to avoid contaminating your scent source are a potential contaminant themselves (Learning Center, 2016) … an odour that your dog learns to detect! 

As Gadbois (2016) has pointed out, our dogs olfactory abilities are so good that no amount of cleaning or careful handling of the scent source or use of gloves will reduce contamination sufficiently for our dogs not to detect it. So, throw away your gloves and tweezers and work with contamination rather than against it! 


Mobile phone odour vs A N Other odour

In addition to some of the possible chemical sources of mobile phone odour (as listed previously), the overall “smell” of a phone is likely to comprise of a number of additional odours – plastics from the casing and human scent from handling the device. With the possible exception of a mobile phone straight from the factory, human scent is very much part of the mobile phone odour picture. It may be a contaminant but it’s also part of the mobile phone cocktail of odours.  

So, here are your first two, of many, potential difficulties. Is your mobile phone Scent Detecting dog using human scent or plastic odour to detect the phone rather than any of the previously listed chemicals? If so, just as my client didn’t have a memory stick Scent Detecting dog, you don’t have a mobile phone Scent Detecting dog.  


Be Systematic – Rule things out!

After familiarising my dogs to the odour of mobile phones – I have a huge collection of old, well-used, phones that I use for this purpose – I then begin to make sure that they’re searching for the cocktail that is the mobile phone odour as opposed to human scent, or plastics, more specifically.

Human Scent

As well as hiding mobile phones, I hide other, similar sized, items that I, and other people, have handled thoroughly. What I want to see is my dog either checking these items out, or ignoring them, before moving on to locate and indicate on the mobile phone – the target odour.

Rather than relying on a change of behaviour (COB) to tell me when my dog has located the scent source, I train a rock-solid passive indication, with duration. This gives me the confidence to let my dog check things out, dismiss things and move on to the correct location before letting me know that they know they’ve found the correct scent source – the mobile phone. My dog has shown me that he’s differentiated between human odour (more generally) – mine and other peoples – and human odour (more specifically) – mine and other peoples – associated with the mobile phone. 

If you’d like to know more about the power of the passive indication, follow this link to one of my previous Blog posts – The Indication. It’s not an optional extra!

Plastics

If you take a look at your mobile phone you’ll notice just how much plastic is used in its construction. Again, in order to confirm that my dog is using the whole cocktail of mobile phone odour to find its location rather than focusing on one odour in particular – plastic – I hide a variety of other, similar sized, plastic items – Spectacles. Plugs. Spectacle cases. Pencil cases. Backs off mobile phones – alongside the mobile phone. I want my dog to demonstrate to me that he can differentiate between plastic items (more generally) and plastic items (more specifically) that are part of the mobile phone odour cocktail.

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L differentiating between a variety of plastics during the early stages of her mobile phone training

Interestingly, last week, BB demonstrated very clearly that he was searching for mobile phone odour as opposed to any other associated odours. The mobile phone had been thrown into a wooded area and, as it landed, part of its plastic casing fell off and came to rest a few feet away from the remaining phone and its contents. BB located the area, checked out the separated piece of plastic casing before dismissing it and moving on to indicate, correctly, on the main part of the phone. Embrace these moments of happenstance


Elemental vs Configural Odour Cues

As Thomas-Danguin et al (2014) point out, “smelling monomolecular odors hardly ever occurs in everyday life, and the daily functioning of the sense of smell relies primarily on the processing of  complex mixtures of volatiles that are present in the environment”. The mobile phone is just one example of a scent source that is comprised of a complex mix of odours.

Some Scent Detecting trainers attempt to address this issue by taking an elemental approach. That is, they identify each odour molecule within a mixture of odours and train their Scent Detecting dog on each of these separate odours. According to an article by Chammah (2016), this is the approach taken by the California Department of Corrections and Rehabilitation when training their mobile phone detecting dogs. They work on each element of the phone – its battery, its SIM card – before training on the whole phone. 

But here’s a question for you. Take a look at this picture …

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What do you smell?

Do you smell roast chicken (A) or broccoli (B) or beans (C) or cauliflower cheese (D) or the whole roast dinner (U)? 

Interestingly, but not surprisingly perhaps, “an odor mixture can carry, beside the elements, another stimulus that is unique to the combination of those elements … usually noted U (unique cue)” (Thomas-Danguin et al, 2014). This mixed odour – U – “can stimulate cortical neurons that are not stimulated by their individual component odorants. This complex combinatorial coding system is consistent with the fact that often a mixture of odorants gives rise to novel perceptual qualities that are not present in each component” (Thomas-Danguin et al, 2014).

And this is why I train my dogs on the whole mobile phone rather than dissecting it into individual olfactory parts. I want my dogs to find mobile phones rather than mobile phone batteries or SIM cards or circuit boards or touch screens. If I want my dogs to find these individual parts, I’ll train them to find these individual parts – a completely separate exercise. As Hall et al (2018) state, “mixtures tend to be perceived configurally, such that the mixture produces a unique percept distinct from the constituent elements, and this may vary depending on the chemical similarities of the components in the mixture”.

Interestingly (and importantly), in a study by Lazarowski et al (2014), “most dogs trained with pure PC [potassium chlorate] did not correctly signal the presence of one or more PC-based explosive mixtures, despite having demonstrated the ability to reliably detect a trained amount of pure PC”. According to Lazarowski et al (2014), possible explanations for a dog’s inability to detect a previously trained substance when presented to him in a mixture include the way in which two or more chemicals might interact with one another making them unrecognisable to the dog. This is referred to as mixture suppression.

In contrast, the ability of a dog to successfully identify individual components in a complex mix is referred to as figure-background segregation (Hall et al, 2018). If, for example, I only wanted my dogs to detect a specific component of a mobile phone or other electronic device – the memory chip – then I would start by familiarising my dogs to that odour alone. During later training I would secrete the memory chips with other substrates – the whole phone, perhaps, or other materials – and continue with figure-background segregation training. This will ensure that my dogs can detect memory chips in a variety of environments and under a number of different conditions. I’m training them to detect memory chips within a roast chicken dinner! This is generalisation in action.


Odour Categorisation

Another generalisation issue in scent detecting involves the concept of categorisation. According to Wright et al (2017), “categorisation is the ability to treat comparable but non-identical stimuli as equivalent by responding to them according to the category to which they belong. Thus, the ability to identify a novel stimulus as a member of a known category allows the organism to respond to it in an appropriate way”

For example, in Cablk et als (2008) study, dogs were able to detect tortoises of all sizes, age and sex, not only those that they’d encountered during training. And this is where my very large collection of old mobile phones comes into its own – different makes, models, styles, sizes, previous owners and colours. My dogs are able to generalise and categorise. Their initial training is conducted using a variety of mobile phones and then, during subsequent searches, they’re able to successfully detect mobile phones they’ve never encountered before. 

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A very small part of my well-used mobile phone collection

In contrast, our dogs are also able to discriminate between “individuals” within a target class. If you really wanted to, it is feasible to train your dog to only detect a certain type of phone. According to Pinc et al (2011), specially trained German Shepherds were able to distinguish the individual scents of identical twins who lived in the same environment and ate the same food! 

Decide what it is you want your dog to detect – an individual within a target class or a target class more generally – a certain type of mobile phone or all mobile phones. Train your dog according to this decision. For instance, if you want your dog to detect a specific type of mobile phone then reward successful detection of that specific type of phone amongst other mobile phones.

You might just be surprised by what your dog can achieve!


Different Search Environments

Training your dog in different environments would seem to be a given. In terms of generalisation, it’s something that we’re always advised to do – from a straightforward Sit or Down to, arguably,  some more complex Scent Detecting challenges. But with Scent Detecting it’s far more than simply a question of whether or not your dog can perform in different types of environment.

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Is the mobile phone acting as a big red flag in this type of environment?

Placing a mobile phone in an outdoor area is likely to act as an attractant to your dog – a big red flag in the environment drawing your dog towards it. I’ve seen many a novice mobile phone detecting dog being trained in outdoor environments. They appear highly successful. They seem (like my client’s dog) to possess some sort of ‘natural talent’. As Ockham would point out, the more likely explanation for their apparent success is that they’re attracted to the unusual in an environment. A mobile phone in woodland is unusual – but so is a rubber duck or pair of spectacles. Your dog may not be detecting what you think he’s detecting!

Environmental factors need to be considered when training your mobile phone detecting dog and that means … start your training indoors.


and in conclusion …

Short and sweet … train systematically! It’s highly unlikely that your dog has any natural mobile phone detecting talents but he does have a super-natural ability to learn. Don’t waste it.


Final Note

As with all of my blogs, I include a reference list. This allows you to investigate the topic a little further, check out the sources of my information and decide for yourself whether my interpretations of the literature represent an accurate reflection of the author’s work. Happy reading.


© Lesley McAllister – Scent : Detect : Find Ltd 2020

www.scentdetectfind.co.uk

References / Further Reading

  1. Cablk ME, Sagebrel JC, Heaton JS and Valentin C (2008) Olfaction-based Detection Distance: A Quantitative Analysis of How Far Away Dogs Recognize Tortoise Odor and Follow It to Source. Sensors. 8. 2208-2222
  2. Chammah M (2016) The Amazing iPhone-Sniffing Prison Dogs. Who knew cell phones had a smell? https://www.themarshallproject.org/2016/06/07/the-amazing-iphone-sniffing-prison-dogs Accessed: 25.08.2020
  3. Compound Interest (2014) The Chemical Elements of a Smartphone. https://www.compoundchem.com/2014/02/19/the-chemical-elements-of-a-smartphone/. Accessed: 20.8.2020
  4. Gadbois S (2016) Modern Dog Training and Science: Are We Doing it Right? Common Misconceptions and Pitfalls. The Science of Sniffer Dogs. Oxford: Two day Conference
  5. Hall NJ and Wynne CDL (2018) Odor mixture training enhances dogs’ olfactory detection of Home-Made Explosive precursors. Heliyon 4. 4. 12. December
  6. Lazarowski L and Dorman DC (2014) Explosives detection by military working dogs: olfactory generalization from components to mixtures. Applied Animal Behaviour Science. 151. 84-93
  7. Learning Centre Valutek Blog (2016) Odor and Color Determine the Quality of Your Cleanroom Gloves. https://blog.valutek.com/home/odor-color-determine-the-quality-of-your-cleanroom-gloves# Accessed: 27.8.2020
  8. Pinc L, Bartos L, Reslova A, Kotrba R (2011) Dogs Discriminate Identical Twins. PLoS ONE. 6(6)
  9. Salter M (? date) Examples of Occam’s Razor. https://examples.yourdictionary.com/examples-of-occam-s-razor.html Accessed: 24.8.2020
  10. Thomas-Danguin T, Sinding C, Romagny S, Mountassir FE, Atanasova B, Le Berre E, Le Bon AM, Coureaud G (2014) The perception of odor objects in everyday life: a review on the processing of odor mixtures. Frontiers in Psychology. June. 5. 504
  11. Wright HF, Wilkinson A, Croxton RS, Graham DK, Harding RC, Hodkinson HL, Keep B, Cracknell NR, Zulch HE (2017) Animals can assign novel odours to a known category. Scientific Reports. 21 August. 1-6

The Indication. It’s not an optional extra!

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Poppy clearly indicating the location of her target scent inside this person’s trouser pocket.

What is an Indication?

The indication or alert is the means by which your dog is able to communicate to you that he’s found the location of his target scent source. It’s a behaviour that, after training, your dog will perform “immediately and unprompted” (Cablk et al, 2006) and is usually categorised as being either passive or (pro)-active in nature. In large part this classification is dependent on the degree to which the indication behaviour involves contact, or direct interaction with, the scent source.

I tend to view passive indications as those where the dog makes minimal or no contact with the scent source. For example, your dog might sit or lie down beside the scent source or place his nose on it or simply stare at it. In contrast, the pro-active indication involves far more direct engagement with the scent source and may include behaviours such as scratching, grabbing, biting and retrieving (Hurt et al, 2009).

Barking is another very commonly used indication. As this behaviour doesn’t involve any direct contact with the scent source, it would seem to be just another type of  passive indication, however, as Hurt et al (2009) point out, as a fundamentally frustrative behaviour that “can accelerate into other frustration behaviors” it is probably better described as a pro-active indication. In explaining their position, Hurt et al (2009) cited the case of search dogs on the Island of Guam who were trained to detect brown tree snakes and indicate their location by barking. Unfortunately, before very long, this behaviour transformed into pawing and biting and, for the safety of the dogs and the welfare of the snakes, the dogs had to be re-trained.


Does my Scent Detecting dog need an indication?

My short answer to this question is YES and here’s why …

Successful Scent Detecting requires your dog to search for, and locate, his target scent source. Without an indication (either passive or pro-active), you’ll have no means of knowing – for sure – that he’s found it. As Scent Detecting is primarily all about finding, it makes little sense to overlook training the one unambiguous way that your dog has to tell you that he has done just that … his indication.


Why spend time training an indication when I can just watch for a COB?

Recently I’ve noticed a growing trend toward relying on a dogs change of behaviour (COB) to help the handler recognise that their dog has located the scent source. Typical changes in behaviour might include slowing down, speeding up, heightened interest in a particular area of a room, walking on tip-toes with head held high … the list of possibilities is almost endless. Each of these behaviours may help you narrow down the location of the target scent source but may also act to totally mislead you.

As an example of just how poor a COB can be as a means of helping you decide that your dog has located the target scent source, take a little look at this video of Dream working amongst farm machinery.

 

At 23 seconds Dream starts to show a heightened interest along the wall of the tractor shed. This extra interest, or COB – standing on tip-toes, head in the air, staying close to the wall, carefully investigating certain areas – continues until approximately 58 seconds into the video when she then moves on to investigate other parts of the building.

I think it perfectly reasonable to suggest that many handlers, seeing their dog showing this level of interest in a particular area, would be sorely tempted to keep their dog working there until something is ‘found’. That something being a false indication.

Put simply;

The dog’s COB → Increased interest in the area by the handler → Increasing interest in the area by the dog → Further interest in the area by the handler → Increasing psychological pressure on dog to ‘find’ something → False (positive) indication by the dog!

This is just one example of  the ‘Clever Hans Phenomenon’ or ‘Clever Hans Effect’ at work – “where a person or animal can be influenced by subtle and unintentional cueing on the part of a questioner” (Jackson, 2005). If you’d like to know more about how the Clever Hans phenomenon can impact your scent detecting, just follow this link to False Indications, Clever Hans and You

At “Scent : Detect : Find” dogs are trained to search independently, following scent plumes and filaments back to source without undue interference from their human partners. This “hands off” approach to scent detecting goes a long way toward mitigating the Clever Hans Phenomenon. In addition, all dogs are trained an indication behaviour that is totally reliable and unambiguous …. so much so that it is easily recognisable, not only to the handler but, to anyone else who might be looking on.

If you review the video again, you’ll notice that throughout her search Dream’s handler remains out of shot. At all times, Nicky gives Dream the necessary space to work independently. Even when Dream shows heightened interest along the wall of the tractor shed (23 secs – 58 secs), Nicky stays clear of the area and waits for Dream to persuade her, by way of her indication, that her target scent source is there … or, as in this particular search … in a completely different area!

And this is why your dog’s indication is not an optional extra. Having a well trained indication allows Nicky to simply watch her dog until that indication comes.

… Nose Touch. Stillness. Duration.


So, what type of Indication is best – Passive or Pro-Active?

I favour the passive indication and train my own, and other handlers, dogs to place their nose as close to the target scent source as possible and hold it there for a minimum of 5 seconds or until their handler asks them to move away.

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Chewee accurately indicating the location of his target scent; a tiny sticky dot.

This type of indication fits well with your dog’s natural olfactory behaviour. Watch your dog when he’s pottering around the garden. What does he do when he catches an interesting odour? He gets his nose as close to it as possible and, more often than not, will stay fixed to it for a lengthy period of time.

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The Passive “nose touch” Indication; a very natural olfactory behaviour

If the scent source is inaccessible to your dog’s nose, for example, placed high up on a wall, or submerged under-water, then this nose touch is transformed easily and quickly into a sustained nose point.

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Bob using his nose to point to his target scent.

 

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Fynn pointing to his submerged target scent.

My reasons for selecting the passive indication and, more particularly, the

nose touch → nose point (if inaccessible)

include;

Safety – Passive indications help minimise any direct engagement with the target scent source. This can be important where either the target scent itself, or its location, may pose a danger to your dog.

For example, tobacco products such as cigarette and cigar butts, nicotine patches and gum and e-cigarette fluid are all harmful to our dogs (Novotny et al, 2011).

Whilst the target scent may be safe for your dog, its location may not be. Sadly, every year there are a number of reported dog fatalities from Acute Water Intoxication following a period of time playing in water (Toll et al, 1999). Typically, these dogs have been repeatedly diving into water to retrieve items thrown in for them whilst, at the same time, ingesting excessive volumes of water (Becker, 2013). Although the actual prevalence of this condition is difficult to confirm – Becker (2013) believing it to be a relatively rare occurrence – retrieving from water should be an activity that you monitor closely and / or consider restricting.

If your dog has a passive indication, all of these potential dangers are markedly reduced.

Precise and unambiguous – There is no mistaking the precise location of the target scent when your dog’s nose is either touching or pointing toward it. Adding duration to the indication adds even more certainty … your dog isn’t simply having a passing investigatory sniff!

Other passive indications such as a sit or a down cannot match this degree of accuracy particularly in situations where your dog is searching for tiny amounts of target scent, so tiny that you would be hard pressed to see it yourself.

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Brook using her nose to indicate on an invisible target scent

Can be used in all situations – No matter where the target scent is located – submerged under water, high up on a piece of furniture, buried underground, in an easily accessible position – it will be possible for your dog to either touch his nose to it or point toward its position.

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Abel using his nose touch to indicate “buried treasure”!

Preserves the integrity of the scent source – A nose touch, or point, minimises any possible damage to the target scent source. This is unlikely to be the case with a Pro-active indication.

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Luytje pointing out a bundle of cash whilst leaving it completely intact!

Requires no further training or re-training in changed circumstances – Starting off your Scent Detecting training with a pro-active indication may seem like a good idea at the time … until you decide to introduce a new target odour. It may be potentially dangerous to you or your dog or very valuable. Ooops … now may be the time to start afresh with your training, this time with a passive indication.


But a Passive Indication is difficult and time-consuming to train, isn’t it?

Well, that all depends on your point of view …

It certainly requires careful, detailed and thorough training to ensure reliability. Training can take anything from just a few hours or, in a limited number of cases (and for some very specific reasons), a few months to complete and this should all happen BEFORE searching “proper” begins.

Without this careful, early, training you are likely to encounter indication problems further down the line. Far simpler to train a reliable passive indication in the first place than have to add in further, often complex, remedial training at some later point in time including “Show me” or “Where is it?” cues.

The “Show me” or “Where is it?” cue is used, predominantly, within competition scent work circles where TIME means POINTS means PLACES! For very obvious reasons, an indication with lengthy duration is rarely trained and, as a consequence, any indication that there is may be missed by the handler. The “Show me” cue is a way of asking the dog to return to the location of the target scent and indicate again. I’m afraid I’m not a great fan of this sticking plaster approach to training. Far better I’d say to train the indication behaviour thoroughly in the first place than add in this extra layer of training complexity.

And then there’s the thorny issue of being “just a pet dog owner”. According to this viewpoint, pet dog owners are rarely interested in training a reliable passive indication. … It takes time … It delays their dog from starting to search until the indication training is complete … They aren’t bothered about an indication … They don’t have the training skills … and so on. Certainly this has never been my experience. The vast majority of my clients are “just pet dog owners” with almost 60 of them having trained reliable passive indications and another 50 or more well on their way.

If you are “just a pet dog owner” … keep this in mind … In a study by McCulloch et al (2006), investigating the ability of dogs to detect early- and late-stage lung and breast cancer, it was a mix of pet dogs with only basic puppy training who (in a matter of weeks) were able to accurately identify breath samples from lung and breast cancer patients. Those of you who are “just pet dog owners” can, and do, achieve great things with your dogs.


So … in conclusion …

As Scent Detecting is all about finding, it makes little sense to overlook training the one unambiguous way that your dog has to tell you that he has done just that … his indication.

If you’d like to know how I train a Passive Indication, look out for a future Blog – one of a series of three – Smoothing out the Lumpy Bits; Why it might be wise to teach the indication before the search and all that back chaining stuff 

And  … NO … your dog’s indication should never be a scent detecting optional extra.


Final Note

As with all of my blogs, I include a reference list. This allows you to investigate the topic a little further, check out the sources of my information and decide for yourself whether my interpretations of the literature are an accurate reflection of the author’s original work. Happy reading.


© Lesley McAllister – Scent : Detect : Find Ltd 2018

www.scentdetectfind.co.uk

https://www.facebook.com/scentdetectfind/?ref=bookmarks


References / Further Reading

  1. Becker K (2013) Water Intoxication: Too Much of a Good Thing. https://healthypets.mercola.com/sites/healthypets/archive/2013/10/28/water-intoxification.aspx Accessed 15.12.2018
  2. Cablk ME and Heaton JS (2006) ACCURACY AND RELIABILITY OF DOGS IN SURVEYING FOR DESERT TORTOISE (GOPHERUS AGASSIZII). Ecological Applications. 16(5). 1926-1935
  3. Hurt A and Smith DA (2009). Conservation Dogs. IN: Helton WS (Ed) Canine Ergonomics: The Science of Working Dogs. Taylor and Francis Group: London.
  4. Jackson J (2005) The Clever Hans effect – a horse’s tale. Critical Thinking. http://www.critical-thinking.org.uk/pdf/clever-hans.pdf
  5. McCulloch M, Jezierski T, Broffman M, Hubbard A, Turner K and Janecki T (2006) Diagnostic Accuracy of Canine Scent Detection in Early- and Late-Stage Lung and Breast cancers. Integrative Cancer Therapies. 5(1). 30-39
  6. Novotny TE, Hardin SN, Hovda LR, Novotny DJ, McLean MK, Khan S (2011) Tobacco and cigarette butt consumption in humans and animals. Tobacco Control. 20. 17-20
  7. Toll J, Barr SC, Hickford FH (1999) Acute Water Intoxication in a Dog. Journal of Veterinary Emergency and Critical Care. 9. 1. 19-22.