A dog, just like a human, has the ability to feel many emotions directly related to a given sit- uation. Out of all the emotions a dog experiences, fear is the one that causes unpredictable behaviour. The undisputed source of stress for a dog may be a visit to a veterinary office and related medical procedures, separation from the owner, but also pheromones left by other animals. The aim of this study was to determine the dog’s stress level in a veterinary office depending on its age. The material was collected by an electronic survey in February 2021 among 381 dog owners. The analysis of the results concerning the dog’s behaviour was carried out according to the age groups of dogs and the five-point scale of answers. In the second part of the study, the occurrence of certain dog behaviours was checked depending on the owner’s stress level. The final stage of the research was the use of selected music as a factor reducing stress in dogs and observation of their behaviour (in January and February 2022). The most common stress behaviours reported by the owners were: lowered body posture, tail tuck, retracted ears, and trying to escape, nose licking. Our own research proved that the calmer the owner is, the lower the frequency of stress reactions in the dog. It was found that dogs exposed to calming music while waiting in the waiting room for an appointment showed fewer stress reactions than dogs waiting in the waiting room without music.