The relinquishment of companion animals to shelters presents significant challenges for animal welfare organizations and has substantial implications for the well-being of both the animals and their owners. This study aims to investigate the reasons for voluntarily relinquishing animals to shelters, to examine species-specific differences (cats and dogs), to compare initial relinquishments to returns (re-relinquishments or readmissions), and to identify potential changes over a 6-year period framing the onset of the COVID-19 pandemic. A retrospective analysis of owner relinquishment records from an open admission shelter in the US was conducted using content analysis, a novel approach in this area of research. A total of 13 relinquishment reason categories were identified, as well as 9 separate categories for specific behavioral issues. Among 2836 randomly selected records, the most frequent reasons cited were Behavior Issues (28%), Housing/Moving (18%), Unable to Care (16%), Too Many Pets (10%), Financial (6%), and Owner Allergies (5%). The most common behavioral reasons reported were Aggression (32% of behavioral surrenders), Social Conflict (28%), and Soiling (13%). However, differences were observed in the pattern of relinquishment reasons based on statistical analyses of species, type of relinquishment, and year. Regarding temporal trends, Housing/Moving and Financial reasons were not found to have changed significantly since the pandemic, but the relative frequency of the category Unable to Care increased significantly in 2022 and 2023. Collectively, these findings partially replicate those from research spanning the past several decades in this area that has employed less systematic methodology and can further be used to help identify and understand the primary drivers of owner relinquishments.
