Elsevier

Journal of Veterinary Behavior

Volume 7, Issue 1, January–February 2012, Pages 11-20
Journal of Veterinary Behavior

Research
The effects of drug detection training on behavioral reactivity and blood neurotransmitter levels in drug detection dogs: A preliminary study

https://doi.org/10.1016/j.jveb.2011.04.002Get rights and content

Abstract

The aim of the present study was to analyze the effects of drug detection training on behavior and blood neurotransmitter levels in drug detection dogs so as to investigate some variables influencing dog reactivity and responsiveness to training. In all, 20 dogs were sampled out of the Guardia di Finanza canine population. All the subjects were born, reared, housed, and trained in the same facility and followed the same training sessions. Dogs’ behavioral reactivity was scored according to a standardized working dogs test to evaluate natural dog attitudes. Plasma samples were analyzed by the high-performance liquid chromatography method to evaluate adrenaline, noradrenaline, L-3,4-dihydroxyphenylalanine, homovanillic acid (HVA), 3-methoxy-4-hydroxyphenylglycol acid (MHPG), 5-hydroxyindole acetic acid (5-HIAA), and 5-hydroxytryptamine (5-HT) levels. 5-HT and 5-HIAA were also analyzed from platelets. The analysis was carried out considering training, breed, and sex as independent variables. From a behavioral point of view, significant differences were recorded before and after training in “sociability,” “playfulness,” “predatory instinct,” and “aggressiveness” scores. Lower levels of platelet 5-HT and 5-HIAA were found after training. Plasma L-3,4-dihydroxyphenylalanine levels differed between sexes, with males showing higher concentrations. These results underline the importance of complete and objective evaluations protocols of the dogs before, during, and after drugs search training to determine effective and successful selection strategies and training procedures.

Introduction

The social importance of drug detection dogs is recognized worldwide. Because of this, the effect of training on dogs’ welfare and behavior needs to be understood to optimize the effectiveness of training methods and to improve the quality of working dogs (Rooney et al., 2007, Rooney et al., 2009, Gaines et al., 2008, Haverbeke et al., 2008a, Leighton, 2009).

Early selection of dogs with a particular aptitude to become a working dog has attracted international attention from both scientists and operational personnel (Taylor and Mills, 2006, Vanderloo, 2009). Knowledge of specific reactivity characteristics related to learning and stress may supply tools for tailoring training programs while also subjectively enhancing attitudes of those who work with the dogs (Diederich and Giffroy, 2009). Such changes will reduce the costs of the training period while increasing the quality of the final product: a well trained, easy to handle dog.

Standardized methods to characterize working dog behavior have been studied and applied by different authors. A strong scientific approach to the development, conduction, and evaluation of behavioral tests as a potential factor influencing dog welfare has been described by Taylor and Mills (2006). Svartberg and colleagues have applied behavioral tests to investigate personality traits in domestic dogs and the consistency of these traits, including the effects of artificial selection on breed-typical behavior in show and working dogs (Svartberg and Forkman, 2002, Svarberg et al., 2005, Svartberg, 2005, Svartberg, 2006). Clear phenotyping plays a key role in every selection plan, as described by Overall et al. (2009) who investigated the link between dog behavior and breed/genotype. Arvelius et al. (2009) characterized the behavior of 2,700 Border Collies using a defined scale (Herding Behavior Characterization) to investigate the heritability of herding behavior traits. The requirements of canine behavioral tests include standardization and validation of results by always considering the “field situation” (Diederich et al., 2009). The link between personality traits and performance in military working dogs has been studied using temperament measurements to predict performance in explosive detection dogs (Gosling and Hilliard, 2009). Haverbeke et al. (2008b) studied the training methods of military dog handlers and their results emphasize the importance of handler–dog interaction and training procedures. The importance of the behavior test in police dogs was shown by Erikson (2009) who focused on 3 critical points: dog suitability for a tryout period, training methods, and behaviors needing deeper investigation.

These methods provide the basis on which to accurately evaluate the ontogeny of a particular behavioral trait, allowing for genetic investigation of the trait of interest (Ruefenacht et al., 2002, Gosling and Hilliard, 2009, Wilsson, 2009).

The organism interaction with its environment is regulated by neurochemical interactions, which include 5-hydroxytryptamine (5-HT) and catecholamines which regulate several behavioral systems, and roles of the dopaminergic and serotoninergic systems in the neurotransmission of the stress response (Puglisi-Allegra and Cabib, 1990, Le Moal and Simon, 1991).

Acute and repeated exposures to stressful stimuli have been shown to increase release and the turnover of 5-HT in specific regions of the brain involved in behavioral and physiological responses to stressors. It has been hypothesized that physiological resistance to repeated stress is associated with an increase of 5-HT release in the hippocampus and that dysregulation of 5-HT release may contribute to the pathogenesis of depression (Robertson et al., 2005, Jiansong et al., 2008, Hedlund, 2009) and anxiety-related behavioral disorders in dogs (Reisner et al., 1996, King et al., 2000, Overall et al., 2001, Seksel and Lindeman, 2001, Overall and Dunham, 1989-2000, Riva et al., 2008). The hippocampus has been proposed to mediate stress adaptation through dense serotoninergic innervations from the dorsal raphe, a pathway that is linked to mood and cognitive function. Stress adaptation allows animals to become tolerant to chronic aversive stimuli (Herman and Cullinan et al., 1997).

It is possible, but unconfirmed, that plasma levels of the evaluated neurotransmitters may reflect what is happening at the brain level. Some authors describe a statistically significant correlation between some assessment of serotoninergic level, including that of its metabolite 5-hydroxyindole acetic acid (5-HIAA) in the cerebrospinal fluid (CSF), and blood levels in subhuman primates. This finding suggests that measurements in blood may be used as a peripheral indicator of central 5-HT (Stahl et al., 1982, Da Prada et al., 1988, Yan et al., 1993, Coccaro et al., 1997).

Our research focused on analyzing the effects of drug detection training on behavior and blood neurotransmitter levels so as to investigate some variables influencing dog reactivity and responsiveness to training (Riva et al., 2007, Marelli et al., 2008)

Section snippets

Subjects

In all, 20 dogs were selected as representative samples of the Guardia di Finanza canine population. These consisted of 18 German shepherd (GS) dogs and 2 Labrador retrievers (LR). There were 11 males and 9 females, and all dogs were intact. The age of the subjects ranged between 12 and 24 months. All of them were born, reared, housed, and trained in the same facility. Dogs were individually housed in an indoor–outdoor kennel. Diet and feeding regimen were the same for all the subjects

Behavioral reactivity

The effect of training on behavior reactivity scores is reported in Table 2. Significant differences occur before and after training in scores for “sociability,” “playfulness,” “predatory instinct,” and “aggressiveness.” Lower scores after training were found for “reaction to stranger friendly contact” (P ≤ 0.05) and “cooperation” (P ≤ 0.01), both subtests of the assessment of “sociability.” “Cooperation” (P ≤ 0.05) and “reaction to physical contact” (P ≤ 0.01) scores were negatively influenced

Discussion

Behavioral reactivity analysis revealed significant differences for various tests. Training results in lower scores for components of “sociability” (“reaction to greeting” and “cooperation”), “predatory instinct” (“grabbing proneness” and “chase proneness”), and “aggressiveness” (“interest in the stranger”). Detection-trained dogs in this study seem to show a less interactive and a more reactive behavior. These results reinforce those reported by Marshall-Pescini et al. (2009) who evaluated

Conclusion

Significant differences for some behavioral traits were noted in dogs trained for drug detection. Not all the applied subtest revealed significant effect of training on dogs reactivity, which may be because of the fact that drug search activity requires very specialized training protocols and dog selection is very strict; conversely, the test we used has been used for the evaluation of the dogs’ responses to environmental challenges and to control the situation in everyday life (Svartberg

Acknowledgments

The authors thank Colonnello Walter Di Mari of the ‘‘Guardia di Finanza” for their hospitality and their technical support during the trial.

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