Hematological profile and erythrocyte osmotic fragility of free-living yellow-footed tortoise Chelonoidis denticulatus (Linnaeus, 1766)

Abstract

The yellow-footed tortoise (Chelonoidis denticulatus, Linnaeus, 1766) is among the most consumed chelonian species in the Amazon region, raising concerns about its conservation status. Furthermore, few studies have been carried out on the parameters of physiological normality of this species in free-living conditions, making it difficult to assess the impact of environmental changes on the physiology of the group. The erythrocyte osmotic fragility (EOF) test is a biomarker of environmental changes that cause membrane damage, decreasing erythrocyte resistance to osmotic stress. However, the physiology of the species is still poorly understood, and the reference ranges for hematological parameters and EOF is unknown for most species in natural conditions. Understanding the reference intervals of the physiological parameters of these animals have fundamental importance to assess when a population is under the effect of environmental stressors, such as xenobiotics, as well as to provide comparative parameters in clinical analyzes for the species. The lack of information on normal EOF values ​​makes it difficult to assess the effects of environmental and clinical changes on the physiology of the species. This study aimed to establish reference intervals for hematological parameters and EOF analysis for C. denticulatus, using thirty tortoises (n = 15 males and n = 15 females). The t-test and Mann-Whitney test were used to compare the hematological parameters between sexes, while the Kruskal-Wallis test was used in the EOF analysis, and the reference range was calculated for males and females together. No statistical differences were found in hematological values between sexes, nor in the hemolysis profile in the EOF analysis, demonstrating that in this population, these parameters of C. denticulatus are similar between sexes during the sampling period. According to the results of this study, we can consider the erythrocytes of these animals osmotically resistant, reflecting the stability of the cell membrane. This study reports for the first time hematological values and EOF analysis for the species C. denticulatus in the wild in a region of the far western Brazilian Amazon.

Keywords: Brazilian Amazon; Chelonian; Hematology; Wildlife.