Hematology and biochemistry of critically endangered radiated tortoises (Astrochelys radiata): Reference intervals in previously confiscated subadults and variability based on common techniques.

Sharon L Deem,Ny Aina Tiana Rakotoarisoa,Jorge Ramón López-Olvera,Maris Brenn-White,Bonnie L Raphael

doi:10.1371/journal.pone.0264111

Sharon L Deem, Ny Aina Tiana Rakotoarisoa + Show 3 more

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https://doi.org/10.1371/journal.pone.0264111

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Abstract

Madagascar’s radiated tortoises (Astrochelys radiata) are critically endangered, threatened by illegal collection, and confiscated in alarming numbers in recent years. Robust population- and technique-specific hematology and biochemistry reference intervals are valuable yet heretofore missing tools for triage, rehabilitation, and reintroduction of confiscated radiated tortoises. We determined reference intervals in 120 previously confiscated, clinically healthy subadult radiated tortoises living under human care within their native habitat at the Tortoise Conservation Center (TCC). Specific analytes measured were manual packed cell volume, total solids, white blood cell (WBC) count and differentials, and biochemistry analytes using a point of care system. To evaluate the effects of different commonly used techniques on these analytes, we compared results between two venipuncture sites (subcarapacial sinus and brachial vein) and three different WBC quantification methods (Natt and Herrick, Leukopet, and slide estimate). Reference intervals were narrower for most analytes, and sodium and potassium were qualitatively higher in the TCC population compared to previously published values from radiated tortoises housed in North American institutions. Creatine kinase, aspartate aminotransferase, glucose and inorganic phosphorus were all significantly greater in brachial samples than in subcarapacial samples. There was poor agreement and evidence of constant and/or proportional bias between all WBC quantification methods. Differences based on time of sample collection were incidentally found in some analytes. These results highlight the need for considering technique, demographic, and environmental factors in creating and applying reference intervals, and contribute foundational knowledge for improving care of radiated tortoises throughout the confiscation-to-release pathway.

Highlights

Radiated tortoises (Astrochelys radiata) are critically endangered chelonians endemic to the spiny forests of southern Madagascar [1]
Study site & population In February of 2020, we examined and sampled radiated tortoises housed at the Tortoise Conservation Center (TCC), a Turtle Survival Alliance (TSA) rehabilitation and captive care facility located in the Ala Mahavelo spiny forest in southern Madagascar within the radiated tortoise’s current range [5]
As globulin concentration is calculated from total protein and albumin, only 13 values were reported for globulin with a mean and standard deviation of 24 +/- 3 g/L, median of 23 g/L, and range of 17–28 g/L

Summary

Introduction

Radiated tortoises (Astrochelys radiata) are critically endangered chelonians endemic to the spiny forests of southern Madagascar [1]. The scale of poaching is reflected in the massive confiscations of radiated tortoises that have taken place in recent years with over 10,000 tortoises recovered in a single 2018 event [6,7]. Over 24,000 confiscated radiated tortoises are currently in rehabilitation facilities in Madagascar, all managed by the Turtle Survival Alliance (TSA), the primary organization responsible for the care of rescued tortoises. Along with measures to minimize illegal collection, successful treatment, rehabilitation, and reintroduction of these and future confiscated radiated tortoises are critical to reversing the steep decline of this species in the wild. Hematology and biochemistry reference intervals based on clinically healthy tortoises are necessary for improving treatment of confiscated animals, selecting healthy candidates for release, and making evidence-based decisions about triage in confiscation events if and when resources allow [11–15]. Species and population-specific reference intervals provide foundational information for subsequent research evaluating the efficacy of rehabilitation protocols and how these analytes may vary under different environmental conditions

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