Ultrasonographic studies of seven rescued Olive Ridley Sea Turtle revealed the following information on the gastrointestinal system: The esophagus was visualized at the ventral-cervical and left-cervicobrachial acoustic windows (Fig 2). The echogenecitiy of lumen was coarser echogenic folds (keratinized papillae) were visualized on cross sections (Fig 3). Stratification of layers of wall was appreciated. The mean±S.E measurement of the wall thickness leaving the esophageal folds was about 0.30±0.02 cm. The contraction and relaxation of esophagus was captured which revealed normal esophageal motility.
The visualization of stomach was made in one out of seven cases through the left axillary acoustic window (Fig 4). The image obtained on ultrasonography was a partial cross section image of stomach with irregular inner wall and fluid within the lumen.
The intestines both large and small intestine was visualized in the prefemoral acoustic window (Fig 5). The small intestine was stratified with five layers as serosa, muscularis, submucosa, mucosa and lumen. The mean±S.E thickness of the layers was 1.40±0.06 cm. The large intestine was visualized with thick wall and stratification was not appreciated as that of small intestine. The mean±S.E thickness of wall measured was 1.52±0.08 cm.
Normal intestinal loops (Fig 6) in four cases (4/7), thickened intestinal loops in one (1/7) and fluid filled loops in one (1/7) gas filled intestinal loops in one (1/7) was identified on ultrasonographic examination.
Coelomic fluid and (free fluid) was identified in two cases (Fig 7) and an inflammatory change was recorded in one of the recently rescued turtle in the cervico-brachial and in coelomic space adjacent to kidneys.
Liver was identified from the prefemoral acoustic windows (Fig 8) as longitudinal section with echogenic and granular parenchyma measuring 6.98±0.08 cm when measured from cranial to caudal. Hepatic vessels were visualized as anechoic tubular structures; gall bladder was visualized at the prefemoral acoustic windows as an anechoic spherical to oval in structure.
The morphology of sea turtles is adapted to its feeding habits which were evident even in esophagus which is marked by cervical papillae and was evicted towards stomach
(Porter 1972; Wyneken and Witherington, 2001; Pressler et al., 2003; Wilkinson, 2004; Magalhaes et al., 2012).
According to
Bleakney (1965) and
Wyneken and Witherington, (2001) papillae in esophagus helps in transport/ facilitate the food to stomach by removing excess water and avoid regurgitation during diving. Microscopically these esophageal mucosa are made of keratinized squamous epithelium which protect them against damages caused by friction generated by food passage and also absence of glands suggest it acts only as organ food transport.
Ultrasonographic studies conducted by
Valente et al., (2008) and
Majo et al., (2016) described esophagus (Fig 2) as a coarse echogenic structure identified as the keratinized papillae when visualized through the distal end of the esophagus at the ventral-cervical and left cervicobrachial acoustic window. The echogenecitiy was coarse with visualization of the echogenic folds with the cross sections of the esophageal lumen was in accordance with studies of the previous authors who worked in sea turtles.
There was no pathological change recorded ultrasonographically in the present study in all the seven rescued Sea Turtle. The thickness of wall by
Chen et al., (2015) described various measurements of esophagus in green turtle hatchlings as 0.1856 cm (1856 mm) and rest of the all layers are 0.05 cm (514 mm).The measurement of esophageal wall leaving the esophageal fold in the present study of Olive Ridley Sea Turtles revealed 0.30 cm (30 mm). The measurement of the esophageal wall however needs further studies in correlation with anatomical and histological section using the dead specimens whichever obtained for postmortem studies. However, the ultrasonographic measurements of the wall thickness as 0.05 cm which was done in the green turtle could not be correlated with the present findings as the study was conducted in the hatchlings and they missed few layers in measurements due to their very small size.
In the present study the stomach could not be visualized through the left prefemoral acoustic windows in six out of seven cases as suggested by
Majo et al., (2016) the visualization was made only in one (1/7) of the case through left axillary windows which was similar to the findings of
Valente et al. (2007) who reported that stomach was frequently imaged through the left axillary windows. In the present study stomach (Fig 4) was visualized partially as more echogenic content. The difficulty in restraining the animal during the procedure might be the reason for difficulty in visualization. However, the findings of more echogenic content in one of the case correlated with the similar findings of previous studies reported by
Valente et al. (2007) and
Majo et al. (2016).
The more echogenic visualization of stomach in one case might be due to presence of intra-luminal gas and food contents which was in concurrence with
Valente et al. (2007). A true data could be obtained about pathology of stomach only when further extensive research is carried out in more number of immediately rescued, stranded or during egg laying season. Further, a detailed study on the ultrasonography in correlation to anatomy and pathology of stomach in animals could yield better results.
The large and small intestine was visualized in the prefemoral acoustic windows as described by
Valente et al. (2007). The wall of the small intestine had stratification of five layers like those in that of mammals
(Mattoon et al., 2002) and
Valente et al. (2007). The serosa and submucosal was identified as echogenic lines. The muscular layer was hypoechoic to anechoic, among which mucosa was thickest and hypoechoic.
In the present study stratification of the layers of small intestine was identified (Fig 5) and was measured and the mean thickness was 1.40 cm.
Majo et al. (2016) described the wall thickness. Large intestine was visualized with no separate layers and this lack of layering might be due to excessive goblet cells in large intestine.
According to
Majo et al. (2016) out of 19 cases, five had ileus with accumulation of fluid and dilated by thickened food material and bowel thickness as 1.30 to 2.25 cm and with mechanical ileus 1.70 to 3.75 cm.
In the present study there was regular peristalsis in all the cases. While two cases had intestinal thickening however the cause could not be identified, it might be due to chronic inflammatory changes as discussed by
Valente et al. (2007). In domestic mammals, cat and horses with similar pattern was observed by
Diana et al. (2003), where there will be thickened intestinal walls due to chronic inflammatory changes.
According to
Stander et al., (2010) ultrasonographic appearance of the gastrointestinal tract of puppies suffering from parvoviral enteritis was characterized by fluid-filled small intestine in 92.5 per cent of subjects and stomach and colon in 80.0 and 62.5 per cent of subjects respectively and observed a mild amount of anechoic free peritoneal fluid in 26 subjects. He also reported that significant increase in the mean sum of thickness of the submucosa, muscularis, muscularis and serosa was noted and in humans with Crohn’s Disease has similar findings. In accordance with
Maffe et al., (2015) bowel is considered to be thickened when the measurement of the wall is more than 3mm and opined that ultrasonography helps in identification of extra intestinal features associated with active Crohn’s Diseases, such as mesenteric fat hypertrophy, enlarged regional lymph nodes and free fluid accumulation in intraperitoneal free fluid. He also suggested that stenoic intestine has a thickened wall, narrow lumen along with reduced or on peristalsis and associated with pre-stenoic dilatation greater than 25 mm in diameter with liquid and air in Lumen. So in our study the thickened intestinal loops strongly suggest chronic inflammatory changes or changes might be due to adaptations in rescue centre.
Fluid filled loops are indicative of ileus as described by
Valente et al. (2007) and
Majo et al. (2016). Gas filled loop was noticed in one case which was in colon. Gas might be accidental entry through the cloacae as described by
Majo et al. (2016). Echogenic content might be food material as formed in other mammals. The presence of coelomic fluid adjacent to intestines might be due to the chronic inflammation. In the present study fluid filled loops, gas filled and thickened loops recorded were in comparison with the studies of described conclusions indicating inflammatory changes of intestines and chronicity.
The liver was visualized in the prefemoral acoustic windows in all the cases.
Valente et al. (2007) used the left and right axillary window to visualize the liver.
Majo et al. (2016) described various per cent of visualization of liver as 52 to 63 per cent in the right and left cervico-brachial acoustic windows and 52 to 73 per cent in the right and left prefemoral acoustic window, whereas partial images of the hepatic parenchyma with transverse and oblique scan planes was also obtained through axillary windows.
