Shelter environments are stressful for dogs, as they must cope with many stimuli over which they have little control. This can lead to behavioural changes, negatively affect their welfare and downgrade the human‐animal bond, affecting re-homing success. Arousal is evident in their behaviour, particularly increased activity and frequent vocalisation. Environmental enrichment plays an important role in reducing arousal behaviour, either through direct physiological effects or by masking stressful stimuli. The present study focused on sensory environmental enrichment, using olfactory and auditory stimuli under shelter conditions. Sixty dogs were allocated to one of four treatments: three types of enrichment, Lavender, Dog appeasing pheromone (DAP) and Music, and a Control group. Stimuli were applied for 3 h/d on five consecutive days. Dogs exposed to DAP lay down more, and those exposed to Music lay down more with their head down, compared to the Control. Those in the Control stood more on their hind legs with their front legs on the exit door, compared to those exposed to Music and DAP, particularly if they had only been in the shelter for a short time. They also panted and vocalised much more than dogs in the three enrichment treatments, which tended to persist during the 4 h period post treatment, and in the case of vocalisation into the subsequent night. The study suggests that all three enrichments had some positive benefits for dogs in shelters, as well as being non-invasive and easy to apply in the shelter environment.

Confinement can be stressful for some dogs and this can lead to behavioural issues and poor welfare. A key component of the stress response is behavioural arousal, characterised by increased alertness and sensory sensitivity. This makes behavioural observations a useful tool to assess stress, as they provide insight into an animal’s internal state. Auditory enrichment has been shown to reduce arousal-related behaviour in dogs, but it is not clear if specific characteristics of a music track, such as tempo and/or pitch, produce these effects. The aim of this study was to compare behavioural responses of dogs to music tracks played with different characteristics (high pitch, low pitch, fast tempo, and slow tempo), as well as white noise and a control. Pitch and tempo modifications were applied to ten piano music songs and the six treatments (four different treatment-song combinations, white noise, and control) were presented daily, for ten minutes each, to ten dogs over ten days. Behavioural changes seemed to be driven by low-pitch tracks, which increased the level of alertness of the dogs. These findings could be related to the Morton’s motivations-structural rules: harsh, low frequency vocalisations signal aggressive motivations in mammals. Dogs may have perceived low-pitch tracks as more unsettling and were therefore more active and alert when listening to them.

Animal shelters can be stressful environments and time in care may affect individual dogs in negative ways, so it is important to try to reduce stress and arousal levels to improve welfare and chance of adoption. A key element of the stress response is the activation of the autonomic nervous system (ANS), and a non-invasive tool to measure this activity is heart rate variability (HRV). Physiologically, stress and arousal result in the production of corticosteroids, increased heart rate and decreased HRV. Environmental enrichment can help to reduce arousal related behaviours in dogs and this study focused on sensory environmental enrichment using olfactory and auditory stimuli with shelter dogs. The aim was to determine if these stimuli have a physiological effect on dogs and if this could be detected through HRV. Sixty dogs were allocated to one of three stimuli groups: lavender, dog appeasing pheromone and music or a control group, and usable heart rate variability data were obtained from 34 dogs. Stimuli were applied for 3 h a day on five consecutive days, with HRV recorded for 4 h (treatment period + 1 h post-treatment) on the 5th and last day of exposure to the stimuli by a Polar^® heart rate monitor attached to the dog’s chest. HRV results suggest that music activates both branches of the ANS, which may be useful to relieve both the stress and boredom in shelter environments.

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