Ovarian remnant syndrome in dogs: a six-case series highlighting the limitations of sole anti-Müllerian hormone testing

Ovarian remnant syndrome (ORS) in bitches presents a diagnostic challenge for first-line veterinary practitioners, particularly when serum anti-M & uuml;llerian hormone (AMH) concentrations yield inconclusive results. In this case series, six bitches are described that were referred for further evaluation due to negative or borderline AMH values, ranging from less than 0.03 ng/mL to 0.48 ng/mL. Clinical presentations varied, with some individuals displaying signs consistent with proestrus or estrus, while others exhibited no obvious symptoms. A systematic diagnostic approach was employed, including vaginal cytology, abdominal ultrasonography, serum progesterone measurement, and, in one case, vaginoscopy.This enabled accurate diagnosis and guided surgical referral. All bitches underwent revision ovariohysterectomy or ovariectomy via laparoscopic or laparotomy procedures. Histopathological examination confirmed the presence of ovarian remnant tissue in each case. In this case series, the limitations of AMH testing as a sole diagnostic tool are highlighted and the use of a comprehensive, multimodal strategy in suspected cases of ovarian remnant syndrome is supported.