Ultrasound examination of coelomic viscera through the plastron in stranded green sea turtles (Chelonia mydas)

Abstract

Many projects have been developed in the last years for the conservation of sea turtles. Young green turtles (Chelonia mydas) often nest on the Brazilian coast. Because they nest in beaches along the coastline and islands, green turtles are susceptible to fishing and accidental ingestion of anthropogenic debris. Early detection of ingested debris is crucial for the survival of  rescued sea animals. Ultrasound (US) has emerged as a viable imaging technique for visceral examination in veterinary medicine. Previous studies have suggested the left and right cervicobrachial, axillary, preand post-femoral areas as the only viable approaches for US examination, but the acoustic windows available for imaging of coelomic structures are limited. It is important to notice that a detailed evaluation of all gastrointestinal
tracts, especially the duodenum, is crucial for detecting foreign bodies and intestinal obstructive processes, as well as obtaining essential information such as intestinal motility and heart frequency. Intestinal motility and heartbeats are not detected through radiographic examination or through the acoustic windows available so far. This study aimed to establish the viability of US examination of coelomic viscera through the plastron in stranded green turtles. Eleven young green turtles rescued by the GREMAR Institute were examined. Turtles were placed in the dorsal decubitus position during US examination, which did not require anesthesia. Even though the plastron is constituted of bones and cartilage, the present research has proven the viability of obtaining US images through it, making it possible to visualize structures undetectable through the acoustic windows previously suggested. The following organs were evaluated through the plastron: heart, stomach, duodenum, jejunum, colon, liver, gallbladder, kidneys, bladder, and spleen (in case of splenomegaly). US imaging through the plastron is a viable approach for detecting ingested artificial
debris, which represents one of the leading causes of death among sea turtles.

Keywords: Chelonia mydas, Green turtles, Plastron, Ultrasound.