The Minnesota Zoo currently houses three female southern stingrays in its Discovery Bay aquarium and 2 in another aquarium.  The oldest is approximately 14 years old and has had a chronic problem with cystic ovaries and fluid accumulation in its uterus. Similar reproductive disorders have been noted in captive female stingrays housed in breeding groups at various other U.S. facilities, as well as stingrays found in the wild.

Currently there are no established treatment protocols for cystic ovaries in stingrays.  Veterinarians here at the Zoo have used a variety of methods to treat this particular stingray including draining the fluid, using hormonal therapy and treating with antimicrobial agents.  However, as with cases at other facilities, none of the treatments have resulted in complete long-term resolutions of the problem.  Ovariohysterectomy has been utilized in a few cases, but is an extremely difficult surgery because of the close association of the uterus with the kidney and body wall. It also renders the animal non-reproductive.

Because of the relatively common nature of reproductive problems in female stingrays, veterinarian and reproductive specialist, Shiho Sumigama DVM, MPVM, PhD, Post Doctoral Fellow is conducting a pilot study to investigate wild Southern stingrays, as well as those in human care, through ultrasound and hormone analysis to better understand what causes this disease, develop diagnostic parameters and establish the incidence of reproductive disease in stingrays with a long-term goal of developing effective treatment options.  Dr. Sumigama who is currently with the South-East Zoo Alliance for Reproduction and Conservation  in Yulee, Florida, recently visited the zoo to assist in training zoo veterinarians on ultrasound and blood collection techniques used for the study.

Stingrays are first restrained in nets by the aquarists and brought to the side of the pool for veterinarians to work on.  The veterinary staff either utilizes waders to get into the pool or reaches over the pool side.  Ultrasound examination focuses primarily on the reproductive tract including ovaries and uterus, but the stomach, heart, kidneys and other organs are also visualized. Blood samples can be obtained from several locations on the stingrays. Previously, staff veterinarians had typically used the base of the tail for blood collection.  However, the wings also have blood vessels which can be utilized as an alternate location for blood collection and Dr. Sumigama demonstrated the technique for that approach for blood collection.  The blood which was collected will be utilized for general health assessment, as well as to develop hormonal profiles for the animals.

Minnesota Zoo veterinarians will repeat the procedures conducted today on a quarterly basis over the next year as part of the study.