Effect of high levels of background noise on dog responses to a routine physical examination in a veterinary setting

Abstract

Veterinary visits result in behavioural and physiological signs of fear and stress for many companion dogs. There are a number of factors that likely contribute to this response, but little is known about possible effects of the acoustic environment. The aim of this study was to assess the effect of elevated levels of common veterinary background noises on fear-related responses in dogs during a routine physical examination in a veterinary setting. Testing took place in an examination room at a veterinary clinic and involved 33 owned companion dogs. All dogs received a standardized physical examination where each dog was either presented with no additional noise (n = 16, control), or a pre-recorded noise track that included the sounds of people talking, dogs barking, and metal doors clanging (n = 17). This noise track was played back with a peak sound level of 68.0 dB, which is comparable to levels previously recorded in clinic settings. The dogs’ behavioural responses (lip licking, yawning, reduced posture, avoidance, vocalizing, trembling) were scored from video by a blinded observer for each stage of the physical examination (i.e., head exam, lymph node palpation, body palpation, temperature assessment, heart rate assessment, and respiratory rate assessment). In addition, willingness to approach the examiner was assessed before and after the examination. For behavioural measures, generalized mixed models and Fisher’s exact tests were used to assess the effects of noise, exam phase, sex, and age, with dog as a random effect. For temperature, a general linear model was used to assess the effects of noise, sex, and age, and the remaining physiological measures were assessed using t-tests. Only respiratory rate was increased with exposure to background noise (F1,31 = 6.74, p = 0.0143); no other responses were affected. However, lip licking (F5,65 = 4.04, p = 0.003), avoidance (F5,158 = 6.36, p < 0.0001), and posture reductions (F5,158 = 3.55, p = 0.0045) were increased during some exam phases. Background noise only affected a single, physiological measure during a routine exam, while exam phase seemed to have a larger influence, affecting various behavioural measures. These results suggest that ceiling effects did not prevent proper assessment of responses to noise. Thus, while noise should be minimized where possible, aspects of the examination itself should be a key focus of future research examining methods to reduce stress in dogs during veterinary examinations.