Seasonal variations in haematological parameters in yellow-bellied slider turtles (Trachemys scripta scripta)

Yellow-bellied slider turtles (Trachemys scripta scripta) are increasingly being used as animal models for experimental purposes. The aim of this work was to generate some seasonal haematological information for captive yellow-bellied slider turtles as a useful and complementary tool for research trials. Blood samples from 30 healthy adult yellow-bellied turtles (13 males and 17 females) were obtained in winter and summer, and complete blood counts were performed. Within each season, the medians for males and females were compared using the Wilcoxon test for independent data. Likewise, the medians for both seasons were compared by means of the Wilcoxon test for paired data. All P-values were corrected using the Bonferroni multiple comparisons procedure. The concordance of the two methods used to determine the thrombocyte count (haemocytometer and smear estimation) was evaluated using intraclass correlation coefficients. The effects of sex were not statistically significant in either season (Bonferroni correction). However, values of heterophils, lymphocytes, basophils, and thrombocytes (haemocytometer method), when compared between seasons, exhibited differences that remained statistically significant after Bonferroni correction. Whereas heterophils were the most numerous leukocytes in summer for both sexes, basophils were the most numerous leukocytes in winter. In addition, lymphocyte percentages were also higher in winter for both sexes. Smear thrombocyte estimations did not show any significant differences between sexes and between seasons. However, when using the haemocytometer method, summer values were significantly higher than winter ones. The concordance between the two methods for measuring the thrombocyte count was not statistically significant in winter, but there was significant concordance in summer. Although the two techniques can be complementary, we recommend smear estimation as an easier and more reliable method. The haematological values obtained in this study may be useful as a complementary profile for researchers carrying out experimental procedures with this turtle subspecies.