title: Validation of an ultrasound-guided technique to establish a liver-to-coelom ratio and a comparative analysis of the ratios among acclimated and recently wild-caught southern stingrays, Dasyatis americana.
abstract: Southern stingrays, Dasyatis americana, are a well-represented elasmobranch species in public aquaria and other facilities throughout the world. This study was conducted at a facility that experienced some mortality and replenished the collection with wild-caught stingrays. A common necropsy finding among the stingrays was a small, dark liver. The objectives of this study were to assess the reliability of an ultrasound-guided technique for establishing a liver-to-coelom ratio by calculating the approximate length of the liver with respect to the coelomic cavity length and then to compare ratios between acclimated captive and wild-caught stingrays. The ultrasound validation phase of the study measured the distance from the caudal margin of the liver to the pelvic cartilaginous girdle and compared it to the actual distance measured during the necropsy or surgery. There was no significant difference found between the ultrasound and actual distance measurements (P = 0.945). This technique was then used to establish liver-to-coelom ratios and compare two groups of stingrays, presumably under different metabolic states at different periods. Liver-to-coelom ratios were established during initial examinations as well as 8 months after cohabitation in a touch pool exhibit. There were significant differences in liver-to-coelom ratios between the two stingray groups at introduction (median difference = 30.9%, P = 0.007) and after 8 months (median difference = 20.5%, P = 0.008). There were also significant differences in the liver-to-coelom ratios within each group at introduction and at 8 months (acclimated group median difference = 20.4%, P = 0.018; wild-caught group median difference 31%, P = 0.008).
authors.affiliation: Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, USA. krystan.grant@colostate.edu
authors.forename: Krystan R
authors.initials: KR
authors.lastname: Grant
authors.forename: Terry W
authors.initials: TW
authors.lastname: Campbell
authors.forename: Tawni I
authors.initials: TI
authors.lastname: Silver
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Olea-Popelka
mesh_terms: D000717:Anatomy, Comparative / Q000379:methods*; D000818:Animals; D000835:Animals, Wild; D000836:Animals, Zoo; D001837:Body Weights and Measures; D018940:Elasmobranchii / Q000033:anatomy & histology*; D008099:Liver / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D009929:Organ Size / Q000502:physiology; D018709:Statistics, Nonparametric; D014463:Ultrasonography / Q000379:methods / Q000592:standards*