The objective of this randomized controlled study was to determine whether supplementing a spayed female dog’s diet with tofu can raise levels of endogenous estrogen (EE), which could be beneficial for estrogen-responsive incontinence. A total of 23 client-owned spayed female dogs diagnosed with urinary incontinence but no other known health conditions participated in the study. Enrolled subjects were randomly assigned to 2 groups: Control Group (n=10) who received normal diet with a placebo supplement or Test Group (n=13) who received tofu supplementation. Supplements were given twice daily for 14 days. Blood samples were collected on Day 0 and Day 14 to assess pre-treatment and post-treatment EE levels. Effects of tofu supplementation were assessed based on group comparison of EE level improvement. The EE level within the Control Group had a nonsignificant decrease from days 0 to 14 (56.9±22.8 → 54.6±25.3 pg/mL, p=0.54). Test Group EE level significantly increased after 14 days (37.1±17.2 → 58.5±28.9 pg/mL, p=0.013). For intergroup comparison, the change of EE levels in the Test Group was significantly greater than the Control Group (Control: -2.3±11.5 versus Test: 21.4±27.5 pg/mL, p=0.0002). The study also found that Test Group owner impression of urinary incontinence improvement (11/13) was significantly greater (p=0.0001) than that in the Control Group (0/10). The results of this study suggest the potential for developing a holistic, natural food therapy for urinary incontinence in spayed female dogs. Future prospective studies, with larger enrollment, that also consider factors such as treatment dose and duration are warranted.