Stress burden for dogs in a simple soundproof cage: Heart rate variability and behavioural analyses

Dog barking, which reaches around 100 dB, often becomes a noise issue in urban environments. One potential solution, a simple soundproof cage, has recently been marketed. To our knowledge, no study has been conducted to investigate what sort of stress burden is imposed on dogs kept in cages, and it may raise animal welfare concerns. The purpose of this study was, therefore, to reveal whether staying in a soundproof cage caused stress for the dogs or not. Ten healthy domestic dogs (5 males, 5 females) of small body size were evaluated. The heart rate variability (HRV), behaviour, and internal and external temperature during confinement in a soundproof cage for each dog were analysed. The HRV analyses revealed no significant differences for any variables between confinement and non-confinement (HR, P > 0.999 9; rMSSD, P = 0.359 4; SDNN, P = 0.359 4; LF, P = 0.652 3; HF, P = 0.128 9; LF/HF, P = 0.222 7). Overall, in our behavioural analysis, there were no significant differences between confinement and non-confinement (P = 0.105 5). In conclusion, the HRV and behavioural analyses did not indicate an increased stress burden on the dogs during confinement in the soundproof cage compared with non-confinement. The inner temperature of the cage was not elevated either. Nevertheless, the stress imposed on dogs caused by a soundproof cage should always be considered on an individual basis, and the time spent in such a cage should always be kept to a minimum.