The use of an open-field model to assess sound-induced fear and anxiety-associated behaviors in Labrador retrievers

Abstract

Previous studies have shown that the playing of thunderstorm recordings during an open-field task elicits fearful or anxious responses in adult beagles. The goal of our study was to apply this open field test to assess sound-induced behaviors in Labrador retrievers drawn from a pool of candidate improvised explosive devices (IED)-detection dogs. Being robust to fear-inducing sounds and recovering quickly is a critical requirement of these military working dogs. This study presented male and female dogs, with 3 minutes of either ambient noise (Days 1, 3 and 5), recorded thunderstorm (Day 2), or gunfire (Day 4) sounds in an open field arena. Behavioral and physiological responses were assessed and compared to control (ambient noise) periods. An observer blinded to sound treatment analyzed video records of the 9-minute daily test sessions. Additional assessments included measurement of distance traveled (activity), heart rate, body temperature, and salivary cortisol concentrations. Overall, there was a decline in distance traveled and heart rate within each day and over the five-day test period, suggesting that dogs habituated to the open field arena. Behavioral postures and expressions were assessed using a standardized rubric to score behaviors linked to canine fear and anxiety. These fear/anxiety scores were used to evaluate changes in behaviors following exposure to a sound stressor. Compared to control periods, there was an overall increase in fear/anxiety scores during thunderstorm and gunfire sound stimuli treatment periods. Fear/anxiety scores were correlated with distance traveled, and heart rate. Fear/anxiety scores in response to thunderstorm and gunfire were correlated. Dogs showed higher fear/anxiety scores during periods after the sound stimuli compared to control periods. In general, candidate IED-detection Labrador retrievers responded to sound stimuli and recovered quickly, although dogs stratified in their response to sound stimuli. Some dogs were robust to fear/anxiety responses. The results suggest that the open field sound test may be a useful method to evaluate the suitability of dogs for IED-detection training.

Minimizing fear and anxiety in working dogs: A review

“…When using an open-field model to assess sound-induced fear and anxiety in potential IED dogs, Gruen et al (2015) exposed animals to loud noises on consecutive days but did not explore differences in the dogs' past experiences or exposure to noises. In the same population of dogs, Sherman et al, (2015) saw differences between individuals in their "emotional reactivity" and the dogs showed consistency in individual response across a large number of stimuli.…”

The effect of a pressure vest on the behaviour, salivary cortisol and urine oxytocin of noise phobic dogs in a controlled test

“…In addition, we found that the strength of noise fear in the home environment, as assessed by the owners, was also positively correlated to lying duration during the noise interval. Similarly, freezing behaviour, has also been shown to be common behavioural response to noise interval (Araujo et al, 2013;Gruen et al, 2015;Tiira et al in Press) Wearing the DEEP vest increased the time the dogs spent near their owner during the noise and recovery intervals. The dogs without vest spent less time near their owner during the noise test than pre-noise and recovery intervals.…”

“…On the other hand, due to the positive correlation between oxytocin and fearfulness at home, it is also possible that this is merely due to these dogs being more fearful in general, and thus more effected by the test. Dogs have large between-individual behavioural variation in how they react in fearful or stressful situations (Araujo et al, 2013;Gruen et al, 2015;Tiira et al In press) and it is therefore difficult to classify one or two behaviours which would most likely indicate a fearful emotional state. Therefore, in this study we decided to measure only the difference in the observed behaviour with or without a vest.…”

Effectiveness of treatments for firework fears in dogs

“…While an analysis of variance indicated no significant treatment or order effect, the number of dogs reducing levels of inactivity during thunderstorm recordings was higher in the treatment group (60%) than in the placebo group (25%)(DePorter et al, 2012). Note, however, that later studies found that many individuals react with an increase, rather than a decrease, in activity to thunderstorm recordings (Gruen et al, 2015; Landsberg et al, 2015a, 2015b).…”