This mixed-methods study investigated themes and factors associated with recent dog adopters declining free over-the-phone support for dog behaviors of concern. At least one behavior of concern (potentially aggressive behavior [PAB], separation-related behavior [SRB], or other behavior of concern [OB]) was reported across 6,317 post-adoption support (PAS) calls made to 3,782 adopters at 2-days, 2-weeks, and 4-months post-adoption. However, for 68.8% of calls, the behavior support offered was declined. Generalized linear mixed-effects modeling and Tukey post-hoc testing showed declining support was significantly more likely at 2-weeks post-adoption compared to 2-days and when reporting behaviors of concern in the following combinations: PAB or SRB individually > PAB and SRB simultaneously > only OB > OB with PAB +/SRB. Inductive thematic analysis produced four themes from adopters' responses around declining help: "Awareness but no action yet", "managing behaviour", "feels support not needed", and "belief of cause". Findings offer insights into adopter attitudes around dog behavior, support needs, and behavioral management. Future research should explore whether declining this support is associated with using other support types and whether uptake impacts overall adoption.