Ovarian Remnant Syndrome (ORS) refers to a condition affecting spayed females, characterized by clinical signs typically seen in intact bitches. In this report, Callie, a 6-year-old spayed female German Shepherd, was presented to the Veterinary Teaching Hospital at the University of Bari for a specialist examination due to serosanguineous discharge from the vulva. All diagnostic tests recommended in the literature were performed to diagnose ORS. Notably, the Anti-Müllerian Hormone (AMH) assay, considered the gold standard for ORS diagnosis, was used, and the dog tested negative based on the established bibliographic cut-off values. However, advanced diagnostic techniques, including CT scans and laparoscopy, were performed, and histological examination ultimately confirmed the presence of ovarian tissue in the dog's abdominal cavity. This clinical case underscores the importance of combining hormonal tests with advanced imaging and surgical diagnostics to ensure accurate diagnosis. It highlights the limitations of relying solely on AMH values and emphasizes the need for further research into diagnostic tests, their cut-off values, and the role of collateral examinations to achieve definitive diagnoses in cases where hormonal assays yield inconclusive results.