Hypofractionated radiation therapy for treatment of an adrenal mass in a ferret

Abstract Background: Ferret hyperadrenocorticism is the most common endocrine disease among domesticated ferrets. Current therapies include adrenalectomy and gonadotropin-releasing hormone analogs. Radiation therapy was used as an alternative noninvasive local therapy option. Case presentation: A 5-year-old male castrated ferret originally presented for pollakiuria. An abdominal ultrasound evaluation revealed an enlarged right adrenal gland with heterogenous parenchyma. Hypofractionated radiation therapy for treatment of the right adrenal mass was planned and performed using a small animal irradiator system. The prescribed radiation protocol was 30 Gray administered in 5 weekly fractions. The volume of the irradiated adrenal mass was serially quantified via the weekly cone beam CT. The adrenal mass volume decreased by 88% over the 10-month period. The ferret was euthanized 10 months postradiation therapy due to progressive co-morbidities, and the body was submitted for necropsy examination. No evidence of adrenal tissue or neoplastic tissue was found on histopathology of the irradiated right adrenal mass at the time of death. Evidence of systemic mycobacteriosis was discovered on necropsy. Conclusion and case relevance: Based on histopathologic evaluation, a complete response was achieved with hypofractionated radiation therapy of the right adrenal mass. Additional studies are needed to evaluate the safety and efficacy of this novel therapeutic approach.