The prevalence of age-related behavioral changes in dogs and the concerns of owners were surveyed using a questionnaire. Seventy-two dogs older than ten years were included in this study. Thirty-two dogs (44.4%) were found to have shown some behavioral changes which were present in canine cognitive dysfunction cases. The prevalence of age-related behavioral changes was significant, and increased remarkably at 14 years. Older dogs were found to have shown a range of behavioral changes. There were no significant effects of other profiles on behavioral changes. Many owners complained about the frequent need to attend animal hospitals and about the behavioral changes of aged dogs. But half of all owners failed to address the problems at all. Although canine cognitive dysfunction syndrome concerned most owners of aged dogs, they lack sufficient information or knowledge about it. Owners relied on animal hospitals not only for treatments for diseases but also for management or consultations on behavioral changes. These results suggest that veterinary clinics should more actively encourage owners to provide care for their aged dogs.