BIBLIOTECA - Anatomia/Fisiologia/Neurociência em Cães

---

Development of a novel paradigm for the measurement of olfactory discrimination in dogs (Canis familiaris)- A pilot study 

Olfactory dysfunction in older human beings has been shown to be associated with an increased risk of cognitive decline, yet age-related changes in olfactory behavior have received little attention in the dog model of human aging. We developed an odor habituation and fine odor discrimination paradigm to test the hypothesis that dogs would show a novelty response toward unfamiliar urine from entire male conspecifics. We tested 26 odor detection dogs (14 females, 12 males) from the New South Wales police dog unit, ranging in age from 1 year 2 months to 11 years 10 months. First, dogs were familiarized with a master odor over 2 presentations. Second, we measured difference in investigation time of a master odor as compared with 5 odor mixtures using the following ratios of novel-to-master odor: 100:0, 80:20, 60:40, 40:60, and 20:80. Dogs habituated to the master odor after the first presentation (t(25) = 6.048, P < 0.001). After 2 dogs that failed to habituate were excluded, there was a nonsignificant trend (t(21) =         – 1.968, P = 0.062) for aged dogs (>8 years, N = 6) to show reduced habituation as compared with middle-aged dogs (5-8 years, N = 9) and with all dogs aged ,< 8 years (N = 18, t(21) =  – 1.883, P = 0.072). Approximately half of the dogs tested (N = 11) failed to show a novelty response toward the 100:0, novel master odor. The remaining dogs (N = 15) showed a significant novelty response toward this odor (mean difference = 1.89 seconds, confidence interval = 0.86-2.84). Investigation of the remaining odor mixtures was not significantly different from investigation of the master odor in all dogs. Further development of this paradigm is needed using naive pet dogs before it can be used as a reliable measure of fine odor discrimination. The current, weak trend for an age effect in habituation warrants further investigation in a larger cohort to determine if this effect becomes significant or if it is simply a manifestation of small sample size and low statistical power. It is recommended that future studies use dogs that have not been trained against or actively discouraged from investigating urine because previous learning may have had a significant effect on the outcomes of this study.

Alterações comportamentais e fisiológicas em cães detectores sob influência  do estresse de confinamento.

Este trabalho foi realizado para estudar os efeitos fisiológicos e comportamentais no desempenho olfativo de cães policiais, após situações cotidianas de estresse que ocorriam previamente à execução da tarefa de detecção de drogas e explosivos. O efeito do estresse foi analisado a partir da simulação de confinamento desses animais até o local da detecção de drogas ou explosivos, em diferentes tempos de transporte, utilizando três tipos de confinamento em caixas de transporte, 30 minutos (30”) 3 horas e 30 minutos (03’30”) e 5 horas e 30 minutos (05’30”). Para avaliar os níveis de cortisol impactados das condições de estresse (confinamentos) nos indivíduos do estudo foi necessário fazer coletas não-invasivas de saliva. Este procedimento se apresenta eficiente, no caso de cães, pois é de fácil utilização e não provoca alterações significativas no estado fisiológico dos animais. Os resultados apresentados demonstraram o aparecimento do estresse e alterações comportamentais, indicando uma diminuição do desempenho olfativo de cães detectores de drogas e explosivos. 

Dogs have been successfully used for many years by military and law enforcement agencies to detect varied substances. However, the science underlying their olfactory detection capabilities has been slow to accumulate and even slower to impact operational training and deployment protocols. Since 1989, the Institute for Biological Detection systems (IBDS) at Auburn University has worked to ameliorate this problem. A number of recent laboratory and field studies have begun to reveal the dog’s olfactory sensitivity, how it recognizes substances, and how it performs in the field. This paper summarizes selected findings and their possible operational consequences.

Dogs have been used in a variety of scent detection tasks for hundreds of years. However, methodological differences in the design of studies concerning canine scent detection make it difficult to directly compare and to evaluate their results. We set out to (1) evaluate the quality and comparability of published literature concerning canine scent detection according to criteria of evidence-based medicine and (2) to determine the influence of the testing system on the outcome of a scent detection task considering two different testing systems. For the systematic literature evaluation we retrieved 31 studies. After applying specific exclusion criteria 14 studies were left for final evaluation. A check list detailing relevant information about the study design and the training and testing process was used. Our results demonstrate many differences in methodology and a high variability of the results of those studies leading to diversity in respect to relevant quality criteria. For the second part of our study seven dogs were trained by means of positive reinforcement to detect black tea (LIPTON Earl Gray, Unilever Deutschland GmbH, Hamburg, Germany) as target scent in two different testing systems, a testing platform and a scent detection board. Our data show that using an optimized training strategy high sensitivity (92.1%) and specificity (97.4%) can be achieved in a short time. Sensitivity and specificity for the detection of a target substance (i.e. black tea) was similar for the two testing systems.

Military working dogs (MWDs) are often required to operate in dangerous or extreme environments, to include hot and humid climate conditions. These scenarios can put MWD at significant risk of heat injury. To address this concern, a two-compartment (core, skin) rational thermophysiological model was developed to predict the temperature of a MWD during rest, exercise, and recovery. The Canine Thermal Model (CTM) uses inputs of MWD mass and length to determine a basal metabolic rate and body surface area. These calculations are used along with time series inputs of environmental conditions (air temperature, relative humidity, solar radiation and wind velocity) and level of metabolic intensity (MET) to predict MWD thermoregulatory responses. Default initial values of core and skin temperatures are set at neutral values representative of an average MWD; however, these can be adjusted to match known or expected individual temperatures. The rational principles of the CTM describe the heat exchange from the metabolic energy of the core compartment to the skin compartment by passive conduction as well as the application of an active control for skin blood flow and to tongue and lingual tissues. The CTM also mathematically describes heat loss directly to the environment via respiration, including panting. Thermal insulation properties of MWD fur are also used to influence heat loss from skin and gain from the environment. This paper describes the CTM in detail, outlining the equations used to calculate avenues of heat transfer (convective, conductive, radiative and evaporative), overall heat storage, and predicted responses of the MWD. Additionally, this paper outlines examples of how the CTM can be used to predict recovery from exertional heat strain, plan work/rest cycles, and estimate work duration to avoid overheating.