• Cause: incomplete removal of ovarian tissue at the time of spay, ectopic ovarian tissue or auto-transplantation of ovarian tissue at the time of spay.
• Signs: return to estrus, swollen vulva.
• Diagnosis: imaging often non-conclusive, although ultrasonography may show retained ovarian tissue. Response to estrus suppression may be helpful, but ultimately exploratory laparotomy and histopathology of found tissue usually indicated for definitive diagnosis.
• Treatment: exploratory laparotomy to find and remove the retained ovarian tissue. Chemical estrus suppression could be used, eg proligestone or deslorelin, but it would be difficult to rule out ovarian neoplasia.
• Prognosis: poor if not treated; risk of hypoestrogenism and potentially development of ovarian neoplasia. Good if all retained tissue is removed, or if estrus is carefully managed by chemical means.

Presenting signs

• Return to estrus and vulval swelling .

Acute presentation

• As above.

Geographic incidence

• Worldwide.

Age predisposition

• Usually seen in ferrets less than 2 years (younger than those with adrenal disease Hyperadrenocorticism / hyperandrogenism - the major other differential for vulval swelling in a spayed ferret).

Gender predisposition

• Seen only in surgically neutered female ferrets.

Cost considerations

• Likely to require surgery, in addition to potential imaging and estrus suppression treatment.

Special risks

• No specific risks, other than if has been showing a prolonged estrus Prolonged estrus, hyperestrogenism Hyperestrogenism may have led to aplastic anemia Aplastic anemia and thrombocytopenia (as per entire females that have not been mated or had chemical suppression of estrus). This should be ruled out prior to further treatment.