INTRAOCULAR PRESSURES OF AQUARIUM-HOUSED COWNOSE RAYS (RHINOPTERA BONASUS) WITH NORMAL AND ABNORMAL OPHTHALMIC EXAMS.

Cownose rays (Rhinoptera bonasus) are common elasmobranchs in zoos and aquaria; however, there is a lack of published information regarding ocular findings in this species. Intraocular pressure (IOP) was measured in a total of 52 cownose rays (Rhinoptera bonasus) from two unrelated aquaria (n = 22 from A1, n = 30 from A2) using a TonoVet rebound tonometer on two settings (dog = D, and unidentified species = P) as part of a full ophthalmologic examination. Adult (n = 38) and juvenile (n = 14) rays were sampled out of water briefly in sternal recumbency. Intraocular pressure (mean ± SD [range]) in the D setting (9.10 ± 2.57 [4-18] mmHg) was higher than the P setting (5.21 ± 2.32 [0-12] mmHg) (P<0.001). Statistical analysis revealed no difference in IOP between right and left eyes, and no correlation between body weight and IOP. No differences in IOP between sex, age group, and location were identified in either setting. However, a significant difference was observed between levels of severity of corneal disease in IOP D setting (P=0.006) and P setting (P=0.024), and levels of severity of intraocular disease in IOP D setting (P=0.034) only. This study provides baseline IOP values using rebound tonometry in aquarium-housed cownose rays with apparent corneal and intraocular lesions and reveals that the D setting may be more sensitive in identifying IOP changes in eyes with intraocular disease.

CLINICAL AND HISTOPATHOLOGIC OCULAR FINDINGS IN AQUARIUM-HOUSED COWNOSE RAYS (RHINOPTERA BONASUS).

Cownose rays (Rhinoptera bonasus) are susceptible to ocular disease with their prominent globes, but despite being popular animals housed in aquaria, there is little published information about their normal ocular anatomy and common pathologic ocular findings. A total of 63 live cownose rays (CNR) from three unrelated, separately housed groups had ocular examinations, and 5 adult rays were selected for ocular ultrasound. All examinations were performed out of the water, and most without anesthesia. Clinical findings were described, categorized, and scored by severity. Sixty-two of 63 rays (123 eyes) had clinical abnormalities, including 110 eyes with corneal pathology (mild = 76, moderate/severe = 34) and 74 eyes with intraocular pathology (mild = 44, moderate/severe = 30). Grey-to-white corneal opacities were the most common pathology (n = 58 rays/100 eyes) followed by cataracts (n = 41 rays/58 eyes), then persistent (or dysplastic) pupillary membranes (n = 14 rays/15 eyes). Most pathologic findings appeared inactive, but one aquarium had several CNR with active ocular pathology. There was a significant association between the diagnosis of moderate/severe corneal and intraocular pathology with age (P = 0.008 and P = 0.014, respectively) and weight (P = 0.001 and P = 0.039, respectively), as well as moderate/severe corneal pathology and group sampled (P = 0.03). There were no other significant variables identified. Additionally, histopathology of 14 eyes (11 rays) from two different facilities were examined, with keratitis (n = 8) and uveitis (n = 2) as the most common lesions. This study shows a high prevalence of pathologic ocular findings in cownose ray eyes with heavier adults more likely to be affected than lighter juveniles. Comprehensive ocular evaluation is important in this species and serial ocular exams and future studies should be pursued to monitor ocular disease progression and better understand possible etiologies.

Cesarian section and long-term outcomes for cownose rays (Rhinoptera bonasus).

Cownose rays (Rhinoptera bonasus) are schooling rays commonly displayed in large groups in public aquariums. They are long-lived, have an annual reproductive cycle, and readily breed in managed care with most pregnancies culminating with the unaided and successful birth of a single neonate. Occasionally, females are observed to have prolonged pregnancies or suffer dystocia during parturition and intervention via a cesarian section (C-section) is required to deliver the neonate. Monthly reproductive monitoring at Ripley's Aquarium of the Smokies using ultrasound to stage pregnancies allows for the prediction of anticipated due dates and guides the decision to assist with delivery. Recognizing when to assist birth and best practices for performing C-section are important for the reproductive health, sustainability, and longevity of this species in managed care. This report describes a surgical technique for C-section in cownose rays and includes short-term complications and long-term outcomes for females.

Surgical outcomes and complications associated with ovariectomy in the southern stingray Hypanus americanus.

Southern stingrays (Hypanus americanus) are relatively large rays that are common and popular in public aquariums because of their size and gentle nature. In aquariums, as well as in the wild, female southern stingrays are fecund. They have a short gestation cycle and can sustain multiple pregnancies each year, each culminating with 2-10 young. This reproductive rate could quickly outpace capacity in managed care and result in a ray surplus. To prevent overpopulation, many aquaria have resorted to single sex groups with a preference for female-only populations. This is an effective way to control population growth, but forces the maintenance of two separated populations of rays; for females this interrupts normal reproductive cycling and replaces it with a protracted non-pregnant condition. An additional consideration is development of reproductive disease in females which is recognized by an enlarged, misshapen, and congested ovary with an abundance of cystic structures and an enlarged uterus with a thickened wall that is often filled with histotroph despite a non-pregnant status. There are no effective long-lasting medical treatments for this type of reproductive disease and mortality is often the result. This report describes a surgical technique for ovariectomy in southern stingrays including outcomes and complications. Ovariectomy as a surgical method prevents unwanted reproduction and has the benefit of reducing reproductive pathologies commonly observed in southern stingrays as they age. Seven stingrays 1-5.2 years old and 42-83.5 cm disc width underwent ovariectomy. After anesthesia, the ovary and a small amount of epigonal was excised via a left para-lumbar incision. Four of the seven rays survived five or more years post-procedure. Two rays died acutely of coelomitis and one ray died of complications unrelated to the procedure. This report details a surgical procedure for ovariectomy in southern stingrays including outcomes, complications, and recommendations.