BACKGROUND: As dogs age, they face various health challenges, and preventive care may be overlooked, impacting their quality of life. Frailty, a concept established in human medicine, has recently been applied to dogs using validated tools like the frailty index and frailty phenotype. This study aims to characterize frailty in senior pet dogs and investigate associated factors. To achieve this goal, 88 apparently healthy dogs, as reported by their owners, voluntarily participated in thorough consultations. These consultations included supplementary examinations such as urinary analyses, hematological assessments, and blood biochemistry. Additionally, owners completed questionnaires addressing their dog's overall health, cognitive and locomotor status, as well as their own attachment to the dog and personality traits. Subsequently, each dog was classified as robust or frail based on the presence of multiple criteria out of a set of five. All collected data underwent preliminary screening by a multiple factorial analysis, followed by binomial logistic regression to model frailty. RESULTS: The final population consisted of 74 dogs, with a frailty prevalence of 41.9% (95% CI: 30.5 - 53.9). In the statistical analysis, older age of the dog, lower owner attachment score, lack of regular deworming, and a disparity in extraversion between owner and dog were identified as contributing factors to frailty. CONCLUSIONS: This study emphasizes the importance of regular deworming and strong owner-pet attachment in reducing frailty in dogs. It underscores the significance of proactive pet care and highlights the complex relationship between owner-dog personalities and canine frailty. This research advocates for a holistic approach that considers both human and canine traits to promote better health outcomes.