Dogs are popular pets in Taiwan but many owners fail to recognise and address undesirable behaviours exhibited by their dogs. Little is known about dog owner attitudes and perceptions in Taiwan. In this study, an online survey was distributed to Taiwanese dog owners to investigate their perceptions of five behavioural factors, including 35 behavioural descriptions, with 479 completed surveys received. Seven behaviour veterinarians in Taiwan were also invited to complete a similar survey to identify their perceptions of the urgency for seeking help for different behaviours. Results showed that Taiwanese dog owners were most likely to seek professional help when faced with behaviours relating to potential medical issues, fearfulness to sounds, and difficulty in handling. In contrast, Taiwanese behaviour veterinarians considered most of the listed behaviours to be urgent except for changes in appetite and mounting. Taiwanese owners were more likely to apply reward-based or environmental and day-to-day management approaches to deal with 26/35 of commonly seen undesirable behaviours, while aversive methods were more prevalently used in 9/35 of commonly seen undesirable behaviours, specifically behaviours related to destruction, aggression, and undesirable play behaviour. Respondents were most likely to ignore behaviours not involving immediate harm to humans or animals, for example, staring at nothing, mounting objects and people’s legs, tail/shadow chasing, air-snapping and lip-licking. Lastly, human factors (e.g. gender, housing style, and owners’ use of learning resources) influenced how owners perceived and responded to the canine behavioural issues posed in this study. In conclusion, there were discrepancies regarding the perceived urgency of seeking professional assistance between dog owners and behaviour veterinarians in Taiwan. To promote dog health and welfare as well as owner safety, veterinary and dog behaviour professionals in Taiwan are encouraged to incorporate the findings of this study by raising owner awareness of concerning behavioural issues, and promoting training approaches that support healthy dog-owner relationships.