Rehabilitation of a green sea turtle (Chelonia mydas) after collision with motorboat in the archipelago of Fernando de Noronha, Brazil

1 Projeto Cetáceos da Costa Branca, Universidade do Estado do Rio Grande do Norte, Mossoró, RN, Brazil. 2 Centro de Estudos e Monitoramento Ambiental, Areia Branca, RN, Brazil. 3 Programa de Pós-Graduação em Ciência Animal, Universidade Federal Rural do Semi-Árido, Mossoró, RN, Brazil. 4 Programa de Pós-Graduação em Ciências Naturais, Universidade do Estado do Rio Grande do Norte, Mossoró, RN, Brazil. 5 Programa de Doutorado em Desenvolvimento e Meio Ambiente, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil. 6 Programa de Pós-Graduação em Biologia Estrutural e Funcional, Departamento de Morfologia, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil. 7 ICMBio Instituto Chico Mendes de Conservação da Biodiversidade, Fernando de Noronha, PE, Brazil.

Of the seven species found worldwide, green turtles (Chelonia mydas) account for most of the reported deaths caused by boat collisions [11], which may be due to several factors, especially the coastal habit of the species [12].
Traumatic injuries may not cause death immediately, but lead to disorientation and weakness, and may serve as entry points for pathogens that then act as immunosuppressants and promote the development of opportunistic infections [13], [14].
Most scientific publications have focused on collisions between boats and North Atlantic whales [15], [16], and there is a scarcity of information on collisions of boats with smaller species, and with all animals in the South Atlantic [17]. Transverse fractures of the carapace, one in the anterior region on the second vertebral shield and corresponding secondary structures including the lateral and marginal shield on the right side ( Figure 1A), and the second, posterior, fracture on the fourth vertebral shield with trauma to the lateral shields on both left and right sides ( Figure 1B    After clinical stabilization, the turtle was referred for surgical reconstruction of the carapace. The turtle was positioned in dorsal recumbency, tramadol hydrochloride was given at 5 mg/kg IM as a preanesthetic medication, and anesthesia was induced by inhalation of 4% isoflurane via a vaporizer with 100% oxygen by mask. The trachea was intubated with a cuffed endotracheal tube. The time from induction to extubation was 110 minutes. After intubation, anesthesia was maintained with 2% sevoflurane via a vaporizer. The turtle moved when we started the operation, so anesthesia was changed to isoflurane at a concentration of 3.5-4.0% during the surgical procedure. The endtidal CO2 partial pressure immediately after intubation was 63 mmHg and was maintained at 22-46 mmHg during surgery using artificial ventilation as needed. All unstable fracture fragments of the lesions were removed, 15 mm steel cannulated conical screws were fixed at the edges of the fracture line, and 0.8 mm steel cerclage wire was used to approximate the edges to support regeneration of discontinuous structures ( Figure 3A).

Discussion and Conclusion
Turtle injuries resulting from trauma caused by collisions with boats usually include multiple carapace and plastron fractures, which are difficult to restore [18], [19], [13]. The type and severity of the injuries may depend on the part of the boat that collides with the animal [19], [13]. In particular, propellers produce multiple wounds that are linear, parallel, penetrating, and regularly spaced at a given angle [13]. These findings were also observed in the present case report. Several techniques have been described for carapace repair, including epoxy resin, screws, wires, and metal plates [20], [21]. However, each technique should be evaluated for the specificities of trauma and the animal's physical and clinical conditions [18]. In addition to fracture, soft tissue injuries with secretion leakage, immediate repair, or use of epoxy-type materials for repair can prevent drainage and cleaning of the underlying wound. This increases the risk of systemic infection, which supports the need for caution and attention when selecting the method to be used [22].
The clinical stabilization and presurgical treatment recommended in this report proved to be effective in controlling pain and infection. The topical use of a supersaturated sugar solution, in addition to keeping the injured tissue viable, contributed to tissue remodeling and wound healing [23], [24], [25], [26].
The healing time reported for carapace damage in turtles is quite variable, as some reports indicate 3 to 9 months [27] and others up to 30 months [28]. In this case, complete wound healing of the affected regions was observed after 115 days.
The good body condition and hydration of the animal at the time of stranding were fundamental to the period in which the turtle was fasted and had to be kept in an area out of the water, with only parenteral nutrition. During this phase, parenteral nutrition provides the minimum necessary conditions until surgical reconstruction of the carapace is performed.