AJVR • Vol 80 • No. 10 • October 2019 931 S outhern stingrays (Hypanus americanus, for- merly Dasyatis americana) are slow to mature and produce small numbers of offspring, 1 making them susceptible to population threats that may in- clude perturbation of coastal breeding and pupping grounds and unregulated commercial and recreation- al fishing. Although the impact of these threats on the long-term survival of the species is unknown, 2 aquarium facilities in the United States are striving to develop sustainable breeding populations of elas- mobranchs such as stingrays for both education and scientific study. Characterization of the reproductive Ultrasonographic and hormonal characterization of reproductive health and disease in wild, semiwild, and aquarium-housed southern stingrays (Hypanus americanus) Natalie D. Mylniczenko MS, DVM Shiho Sumigama DVM, PhD Jennifer T. Wyffels PhD Catharine J. Wheaton PhD Tristan L. Guttridge PhD Stacy DiRocco DVM Linda M. Penfold PhD Received December 10, 2018. Accepted March 18, 2019. From the Departments of Animal Health (Mylniczenko) and Science Operations (Wheaton), Disney’s Animals, Science & Environment, Animal Programs, 1200 Savan- nah Cir, Lake Buena Vista, FL 32830; South-East Zoo Alliance for Reproduction & Conservation, 581705 White Oak Rd, Yulee, FL 32097 (Sumigama, Wyffels, Penfold); Bimini Biological Field Station, South Bimini, Bahamas (Guttridge); and SeaWorld Orlando, 7007 Sea World Dr, Orlando, FL 32821 (DiRocco). Address correspondence to Dr. Mylniczenko (natalie. mylniczenko@disney.com). OBJECTIVE To characterize physical examination, plasma biochemical, and ultrasono- graphic fndings in aquarium-housed, managed semiwild, and wild southern stingrays ( Hypanus americanus) with and without reproductive disease. ANIMALS Southern stingrays from aquarium (n = 48), lagoon (managed semiwild; 34), and wild (12) habitats. PROCEDURES Limited, opportunistic prosections were performed of presumed ana- tomically normal wild southern stingrays and compared with fndings for aquarium-housed stingrays with reproductive disease. Ultrasonographic video data from both groups were used to assign a score (1 to 5) indicating increasing severity of ovarian and uterine reproductive disease. Plasma to- tal 17β-estradiol, estrone, progesterone, and testosterone concentrations were measured with enzyme immunoassays validated for use in southern stingrays. RESULTS Ultrasonographic ovarian scores were signifcantly correlated with uterine scores. No reproductive disease was detected in semiwild or wild stingrays, but 65% (31/48) of aquarium-housed stingrays had developing or advanced reproductive disease (ie, ultrasonographic ovarian or uterine score of 4 or 5). Signifcant correlations were identifed between ovarian and uterine disease status and plasma concentrations of all steroid hormones except testosterone. CONCLUSIONS AND CLINICAL RELEVANCE Findings suggested that ultrasonography and plasma hormone concen- trations may be useful in the identifcation of reproductive disease and determination of disease severity in southern stingrays. (Am J Vet Res 2019;80:931–942) biology of a species is the first step toward under- standing the requirements for conservation and long- term survival under managed care, yet little is known about the natural reproductive biology of H ameri- canus, with most available reproductive data derived from aquarium-housed animals. 3 In the authors’ experience, reproductive disease has been identified in groups of female southern stingrays housed at multiple aquaria, suggesting that this is a widespread problem and necessitating the de- velopment of descriptive criteria and diagnostic tools to distinguish between healthy and abnormal repro- ductive physiology. This perceived high incidence of disease is in contrast to findings in a postmortem survey 4 involving tissues of aquarium-housed elasmo- branchs, in which only 3% (2/75) of southern sting- rays had reproductive disease. Information regarding reproduction in south- ern stingrays is limited, as are descriptions of the ABBREVIATIONS E 1 Estrone E 2 17β-estradiol EIA Enzyme immunoassay HRP Horseradish peroxidase P 4 Progesterone T 5 Testosterone Unauthenticated | Downloaded 02/24/23 02:28 PM UTC