Simon Gadbois | Dalhousie University (original) (raw)

Papers by Simon Gadbois

Springer eBooks, Dec 31, 2022

Frontiers in allergy, Mar 28, 2024

Frontiers in Allergy, 2024

Introduction: Post-traumatic stress disorder (PTSD) is an impairing mental health condition with ... more Introduction: Post-traumatic stress disorder (PTSD) is an impairing mental health condition with high prevalence among military and general populations alike. PTSD service dogs are a complementary and alternative intervention needing scientific validation. We investigated whether dogs can detect putative stress-related volatile organic compounds (VOCs) in the breath of people with trauma histories (54% with PTSD) exposed to personalized trauma cues. Methods: Breath samples were collected from 26 humans over 40 experimental sessions during a calm (control breath sample) and stressed state induced by trauma cue exposure (target breath sample). Two scent detection canines were presented with the samples in a two alternative forced choice (2AFC) discrimination and yes/no detection task. The 2AFC task assessed the dogs’ ability to discriminate between the two states within the breath samples of one individual. The detection task determined their ability to generalize the target odour across different individuals and different stressful events of one individual. Signal Detection Theory was applied to assess dogs’ sensitivity, specificity, precision, and response bias. Results: The dogs performed at ~90% accuracy across all sample sets in the discrimination experiment, and at 74% and 81% accuracy, respectively, in the detection experiment. Further analysis of dog olfactory performance in relation to human donor self-reported emotional responses to trauma cue exposure suggested the dogs may have been detecting distinct endocrine stress markers. One dog’s performance correlated with the human donors’ self-reported fear responses and the other dog’s performance correlated with the human donors’ self-reported shame responses. Based on these correlations between dog performance and donor self-report measures, we speculate that the VOCs each dog was detecting likely originated from the sympathetico-adreno-medullary axis (SAM; adrenaline, noradrenaline) in the case of the first dog and the hypothalamo-pituitary-adrenal axis (HPA; glucocorticoids) in the case of the second dog. Conclusion: Our proof-of-concept study is the first to demonstrate that some dogs can detect putative VOCs emitted by people with trauma histories when experiencing distress theoretically associated with the intrusion and arousal/reactivity symptoms of PTSD. Results have potential to improve the effectiveness and training protocol of PTSD service dogs with a focus on enhancing their alert function.

The use of dogs in biomedical diagnosis, detection and alert as well as for the search and monito... more The use of dogs in biomedical diagnosis, detection and alert as well as for the search and monitoring of species-at-risk is an emerging field of research. Standard practices are converging towards models that are not necessarily consistent with the well established field of (animal) psychophysics. We briefly discuss the different challenges of applied canine olfactory processing and discuss the adoption of more valid and reliable methods. For mostly historical reasons it seems, scent processing dogs are trained and tested using multiple alternative stimuli in choice tasks (e.g., line-ups including 6 alternative choices, or 6AFC). Data from psychophysics suggest that those methods will reduce or at the very least misrepresent the accuracy of canines. Unless canines are an exception to the rule, sensory, perceptual and cognitive arguments (e.g., Gadbois & Reeve, 2014) can be made against most multiple alternative forced choice tasks (mAFC’s) in favor of detection tasks (yes/no and go/no-go procedures) or, as a compromise, simpler discrimination tasks (2AFC or 3AFC at most). We encourage the use of Signal Detection Theory as it focusses on two important factors in defining the validity and reliability of scent processing dogs: 1) It is a robust measure of sensitivity, an important factor in both diagnosis and sensory detection, and, 2) It describes the type of errors (false alarms vs. misses) that a given dog is most likely to commit, allowing for a solid assessment of performance and potentially a readjustment in training. We give an example with Diabetes Alert Dogs (DAD’s) specialized in Hypoglycemia Detection in vitro and discuss the potential advantages of keeping a low number of alternatives during training and testing, the importance of low saliency training (LST), as well as adopting pure detection tasks requiring a response commitment from the dogs for both “yes” and “no” responses. The value of d’ (a detectability or discriminability measure) and bias measures (criterion) are discussed in the context of canine selection, performance assessment and diagnostic accuracy across applications.

PLOS ONE, Apr 14, 2021

Medical Alert Dogs (MADs) are a promising support system for a variety of medical conditions. Eme... more Medical Alert Dogs (MADs) are a promising support system for a variety of medical conditions. Emerging anecdotal reports suggest that dogs may alert to additional health conditions and different people other than those that they were trained for or initially began alerting. As the use of medical alert dogs increases, it is imperative that such claims are documented empirically. The overall aims of this study were to record the proportion of MAD owners who have a dog that alerts to multiple health conditions or to people other than the target person and to determine whether any sociodemographic variables were associated with dogs alerting to multiple conditions, multiple people, or both. MAD owners completed an online survey that contained a series of forced choice questions. Sixty-one participants reported a total of 33 different conditions to which dogs alerted. Eighty-four percent of participants reported that their dog alerted to multiple conditions and 54% reported that their dog alerted to multiple people. This is the first study to document that a large percentage of people report that their MAD alerts to multiple conditions and/or to multiple people. We present a discussion of how these alerting abilities could develop, but questions about the underlying mechanisms remain.

Journal of Hospital Infection, May 1, 2017

Letters to the Editor Canine scent detection as a tool to distinguish meticillin-resistant Staphy... more Letters to the Editor Canine scent detection as a tool to distinguish meticillin-resistant Staphylococcus aureus Sir, Meticillin-resistant Staphylococcus aureus (MRSA) is a frequently reported hospital-and community-acquired pathogen. New fast and inexpensive detection tools are needed for detection. Current molecular assays are based on detection of Staphylococcal Cassette Chromosome mec (SCCmec), which contains the mecA gene [1]. Secondgeneration polymerase chain reaction assays are single-locus assays targeting the open reading frame X (orfX)eSCCmec junction, and continue to have specificity issues related to strains which have lost the mecA gene but retained the SCCmec cassette junction (SCCmec remnant strains, MSSAr) [1,2]. Canine scent detection is a rapidly expanding field of study in medicine [3e5]. Studies have shown that meticillin-resistant and-susceptible (MSSA) S. aureus may be differentiated based solely on their volatile organic compound (VOC) profiles [6,7]. We hypothesized that canine scent detection could be used as a diagnostic tool for the detection of MRSA. Our objective was to determine whether dogs could distinguish MRSA from the similar strains: MSSA, mecA-positive Staphylococcus epidermidis (MRSE), and MSSAr, using bacterial cultures. The study was approved by both the North York General Hospital Research Ethics Board and the Centre for Phenogenomics Animal Care Committee. The MRSA type strains Canadian (C)MRSA-2 (SCCmec type II, USA100) and Canadian MRSA-10 (SCCmec type IV, USA300) were obtained from the National Microbiology Laboratory (Winnipeg, Canada). Other strains used were S. aureus ATCC Ò 25923Ô (MSSA), a clinical isolate of MRSE, and SCCmec (Type I) remnant MSSA (MSSAr) [8]. Isolates were inoculated on to fresh 5% sheep blood agar plates (BAP) in a set pattern (Supplementary

Springer eBooks, 2014

Canine olfaction is a rich field of study for the behavioural sciences and neurosciences, and it ... more Canine olfaction is a rich field of study for the behavioural sciences and neurosciences, and it is rich in interdisciplinary connections. This chapter will explore the neurocognitive and neuroconative bases of olfaction (the neurophysiological foundations of cognition and motivation), and discuss the behavioural, psychological, and semiotic dimensions of scent processing. It will cover the basic psychophysics of olfaction and the methodologies allowing us to explore this sensory modality, as well as the complex cognitive and motivational dimensions of scent. This chapter will open with an overview of the different disciplines involved in the study of canine olfaction. Some basic anatomy and neuroscience will be reviewed, mostly with direct reference to behaviour and associated psychological processes (e.g., cognitive, motivational, and affective systems). For the behavioural aspect of olfaction, a discussion of the contrasting, yet complementary methods of ethology and experimental psychology will be examined. The importance of both field and laboratory research will be highlighted. Olfaction ''in context'' will also be discussed in reference to zoosemiotics and in order to understand the canine olfactory psychoethology in its most meaningful and functional dimension: processing ''signs'' (including symptoms as with dogs trained for biomedical applications such as symptom detection). We will conclude with a short commentary on the human-canine sensory symbiosis with sniffer dogs. 1.1 The Sciences of Canine Olfaction Canids, like most mammals (and many other vertebrates, such as reptiles), live in an olfactory world. Their Umwelt, or ''sensory world'', is impressively different from ours (see also Horowitz and Hecht, this volume). Observing our dogs exploring

Canadian Journal of Zoology, Feb 1, 1996

The relation between involvement in aggressive interactions and a physiological index of stress w... more The relation between involvement in aggressive interactions and a physiological index of stress was examined in a captive timber wolf pack (Canis lupus). Urine samples from known individuals were collected from snow throughout the mating season and analyzed for levels of the stress responsive hormone cortisol. When expressed relative to creatinine concentrations in the sample (thereby correcting for differences in urine concentration and dilution in snow), individual differences in urinary cortisol levels were found. These differences were consistent with behavioural data on aggression collected during the same period. Although males engaged in intrasexual aggression more frequently, female aggression was more serious in that females were more likely to be the targets of group chases and attacks. The dominant and only breeding female also aggressed against the two highest ranking males during courtship and mating contexts. The lowest ranking female had a significantly higher cortisol:creatinine (C:C) ratio than all other females, and the second-ranking (beta) and most aggressive male, whose social position was unstable, had significantly higher C:C ratios than most other males. The data also suggest that urinary C:C ratios increase during the mating season for at least some individuals and vary in response to acute social stressors. The C:C ratios presented are similar to those reported from the urine of domestic dogs and a small sample of wild wolves, suggesting that these data from captive animals are not unusual. Comparisons with literature on primates and potential applications of these techniques are briefly discussed.

Canadian Journal of Diabetes, Oct 1, 2017

cancer risk with RAI. In our updated meta-analysis, the risk difference (RD) for SPM in RAI group... more cancer risk with RAI. In our updated meta-analysis, the risk difference (RD) for SPM in RAI group was −4.9 SPM cases per 1000 TC patients (95% CI −26.5 to 16.8, p=0.658, n=63,908 from 9 studies). The RD for breast cancer after RAI was −6.1/1000 TC patients (95% CI −16.4 to 4.2, p=0.246, n=66,400 from 6 studies). The RD for leukemia (any type) was 2 per 10,000 TC patients, (95% CI 0 to 4.0, p=0.0134, n=264,179 from 3 studies). There was significant heterogeneity in the pooled analyses for any SPM and breast cancer. Conclusion: There is conflicting observational evidence on SPM risk for TC patients treated with RAI, underscoring the need for more long-term, prospective studies. This data suggests the lack of a clinically significant increased risk of SPM with RAI.

Canadian Journal of Diabetes, Feb 1, 2020

An idiographic investigation of diabetic alert dogs' ability to learn from a small sample set

Canadian Journal of Zoology, 1998

ABSTRACT In a previously published report, a male timber wolf (Canis lupus) was identified as hav... more ABSTRACT In a previously published report, a male timber wolf (Canis lupus) was identified as having significantly elevated urinary cortisol to creatinine ratios relative to other males in the pack. This second-ranking animal, whose social status was being challenged, was involved in far more aggressive interactions than any other pack member. The wolf died 3 years later from gastric and splenic torsion. Necropsy revealed a unilateral adrenal tumour identified by histology and electron microscopy to be a cortical adenoma. This finding is based on the presence of abundant lipid and no evidence of neurosecretory granules. Whether the increased cortisol levels in this wolf were the result of social stress, as originally suggested, the tumour, or both is uncertain.

Handbook of behavioral neurobiology, 2001

10 The Development of Action Sequences John C. Fentress and Simon Gadbois Intronuction The Brain ... more 10 The Development of Action Sequences John C. Fentress and Simon Gadbois Intronuction The Brain functions for action.(Edelman, 1987, p. 63) Many years ago, Lashley (1951) challenged behavioral neuroscientists to examine movement properties and the serial order of ...