A Baseline Model For Estimating the Risk of Gas Embolism in Sea Turtles During Routine Dives.

Sea turtles, like other air-breathing diving vertebrates, commonly experience significant gas embolism (GE) when incidentally caught at depth in fishing gear and brought to the surface. To better understand why sea turtles develop GE, we built a mathematical model to estimate partial pressures of N2 (PN2), O2 (PO2), and CO2 (PCO2) in the major body-compartments of diving loggerheads (Caretta caretta), leatherbacks (Dermochelys coriacea), and green turtles (Chelonia mydas). This model was adapted from a published model for estimating gas dynamics in marine mammals and penguins. To parameterize the sea turtle model, we used values gleaned from previously published literature and 22 necropsies. Next, we applied this model to data collected from free-roaming individuals of the three study species. Finally, we varied body-condition and cardiac output within the model to see how these factors affected the risk of GE. Our model suggests that cardiac output likely plays a significant role in the modulation of GE, especially in the deeper diving leatherback turtles. This baseline model also indicates that even during routine diving behavior, sea turtles are at high risk of GE. This likely means that turtles have additional behavioral, anatomical, and/or physiologic adaptions that serve to reduce the probability of GE but were not incorporated in this model. Identifying these adaptations and incorporating them into future iterations of this model will further reveal the factors driving GE in sea turtles.

Surgical Management of a Chronic Neck Abscess in a U.S. Navy Bottlenose Dolphin.

Surgical intervention on cetaceans is rarely performed due to challenges including general anesthesia and post-operative wound healing. This report describes the evaluation and treatment of an adult female bottlenose dolphin (Tursiops truncatus) with the US Navy Marine Mammal Program, with a chronic ventral cervical abscess caused by Candida glabrata. Despite aspiration and lavage along with multiple antifungal drugs, the patient developed inspiratory stridor with decreased performance level and surgical treatment was pursued. Under general anesthesia with the dolphin in dorsal recumbency position a 12-cm longitudinal ventral midline neck incision was used for exploration. Intraoperative ultrasound aided the identification of surgical landmarks and the abscess cavity. After adequate drainage and curettage, a closed-suction drain was placed in the surgical site. Retention sutures were used to close the incision and the external drain bulb was secured to a pectoral fin strap. One-year post-op, the dolphin was clinically normal and follow-up imaging showed no significant recurrence of the abscess. This case demonstrates a novel surgical approach of managing abscesses in dolphins, including placement and management of a negative suction drain in a submerged patient. The successful collaboration between veterinary anesthesiology, veterinary medicine, radiology, and general surgery allowed the patient to continue her normal activities as a full-duty service member.