DAO prepress abstract   -  DOI: https://doi.org/10.3354/dao03823

ABSTRACT: Significant knowledge gaps remain in our understanding of the reproductive physiology and diseases of elasmobranchs. The objective of this work is to describe the clinical, imaging, and pathologic findings associated with polycystic ovaries in cownose rays housed in public aquariums. Ten adult, female, cownose rays (Rhinoptera bonasus) housed in four public aquariums presented with variable, nonspecific (lethargy, anorexia, cutaneous discoloration) or no clinical signs. Clinical antemortem examination revealed a large, heterogeneously hyperechoic mass with many variably sized and shaped anechoic cavitations within the coelom on ultrasound in two animals. Necropsies of ten animals revealed polycystic, fluid-filled ovarian masses filling approximately 65-75% of the coelomic cavity in severe cases along with substantial liver atrophy. Microscopically, the masses were composed of delicate connective tissue supporting a combination of cysts lined by attenuated squamous to foamy columnar epithelium, hemorrhage, embedded anovulatory follicles, and oocytes along the periphery. Polycystic ovarian disease is understudied in elasmobranchs and presumptively resulted from failure of follicular ovulation in these cases. Along with southern stingrays, cownose rays appear at heightened risk for developing polycystic ovaries under human care. Further study into disease prevalence, epidemiologic factors, etiopathogenesis, and treatment modalities are needed in order to prevent and medically manage this condition in cownose rays under human care.