Susan Little FELINE REPRODUCTION Problems and clinical challenges

Ovarian remnant syndrome (ORS) is the presence of functional ovarian tissue with signs of estrus after ovariohysterectomy or ovariectomy. Signs of estrus may occur weeks to many years after surgery and include lordosis, vocalizing, rolling on the ground and receptivity to intact males.1 The cause of ORS is failure to remove all or part of an ovary at surgery, or revascularization of ovarian tissue inadvertently dropped into the abdomen during ovariohysterectomy/ovariectomy.2,3 Neoplasia in ovarian remnants, such as granulosa cell tumor, is a rare cause of ORS. Age at the time of surgery and the breed of cat do not appear to influence the risk of ORS, although one report did not find any cases in queens spayed before 4 months of age.1