Hematologic and biochemical characteristics of stranded green sea turtles

Abstract

To improve understanding of pathophysiologic processes occurring in green sea turtles ( Chelonia mydas) stranded along the east coast of Australia, we retrospectively examined the hematologic and biochemical blood parameters of 127 green turtles admitted to 2 rehabilitation facilities, Dolphin Marine Magic (DMM) and Taronga Zoo (TZ), between 2002 and 2016. The predominant size class presented was small immature animals (SIM), comprising 88% and 69% of admissions to DMM and TZ, respectively. Significant differences in blood profiles were noted between facility, size, and outcome. Elevated levels of aspartate aminotransferase (AST) and heterophils were poor prognostic indicators in animals from TZ, but not DMM. SIM animals at both institutions had lower protein levels than large older (LO) animals. SIM animals at DMM also had lower hematocrit and monocyte concentration; SIM animals at TZ had lower heterophil counts. Urea was measured for 27 SIM animals from TZ, but the urea-to-uric acid ratio was not prognostically useful. Strong correlations were seen between AST and glutamate dehydrogenase (GDH; r = 0.68) and uric acid and bile acids ( r = 0.72) in the 45 SIM animals from DMM in which additional analytes were measured. χ contingency tests showed that the most recently published reference intervals were not prognostically useful. A paired t-test showed that protein levels rose and heterophil numbers fell in the 15 SIM animals from TZ during the rehabilitation process. Our results indicate that further work is required to identify reliable prognostic biomarkers for green turtles.

The use of echocardiography as a health assessment tool in green sea turtles (Chelonia mydas)

“…This results in increases in the thickness of the interventricular septum and ventricular free wall in other species and decreases in the internal diameter of the ventricle at systole and diastole 23,24 . Although no significant correlations were seen between haematocrit and total plasma protein and the structural or functional parameters discussed, debilitated green sea turtles can present with concurrent anaemia and hypoproteinemia 3 that may decrease the potential of these biomarkers to accurately reflect the animal's state of hydration. Interestingly, upon admission in this study, animals showed an increased fractional shortening, which has not been reported previously with dehydration 25 or pseudohypertrophy 23,24 and is contrary to what is expected in a compromised physiological state 26,27 …”

“…This may play a role in the development of cachexia, which is common in debilitated green sea turtles 4 . Upon admission to rehabilitation clinics, sick animals often show significantly lower levels of plasma protein, 3 higher levels of urea 4 and poor body condition, indicating catabolism of skeletal muscle 37 . The suggested causes for this syndrome have previously included malnutrition, infectious disease and/or toxicoses 4 .…”

“…The term ‘hepatorenal insufficiency’ has been used to describe the clinical presentation of green sea turtles with concurrent elevations in renal and hepatic enzymes 4 . Given the lack of histological disease associated with the syndrome, decreased cardiac output has been previously proposed as a potential mechanism 3 . Although fractional shortening was increased in debilitated animals relative to their healthier counterparts, within the debilitated group, there was a strong inverse correlation between fractional shortening and uric acid.…”

“…Health assessments on green sea turtles ( Chelonia mydas ) can be difficult, with poor correlation noted between clinical signs and histologically diagnosed disease, 1 inconsistencies among quantitative body condition calculations and subjective appearance 2 and broad reference intervals for blood parameters that are of limited prognostic significance 3 . Common findings in animals presented to rehabilitation clinics include non‐specific signs of chronic disease, including cachexia, spirorchiidiasis and a syndrome described as ‘hepatorenal insufficiency’, based on elevated hepatic and renal enzymes 4 .…”

“…This study examined the cardiac function in green sea turtles ( C. mydas ) undergoing rehabilitation and the correlation between cardiac parameters and haematologic and biochemical profiles in debilitated turtles. The objectives of this study were to investigate the application of echocardiography as a health assessment tool and to test the previously hypothesised role of hypoperfusion contributing to previously described health ailments in this species, including hepatorenal syndrome 3 …”