Efeito de variáveis intrínsecas e extrínsecas no perfil hematológico e bioquímico de Phrynops geoffroanus (SCHWEIGGER, 1812) e Chelonoidis carbonarius (SPIX, 1824)

Abstract

Chelonians are an important and abundant component of many terrestrial and aquatic ecosystems. However, they are considered one of the most threatened vertebrate groups in the world. Therefore, the medical evaluation of Testudines, free living or in captivity, is essential to understand their health status, being a tool for the conservation of species. As ectothermic animals, clinical signs are not always evident, and the evaluation of the clinical condition in chelonians is often complemented with laboratory tests. The interpretation of the results of hematological and biochemical tests in reptiles is a challenge, because they are modulated by intrinsic and extrinsic factors. Although the influences of diet, environment, season and reproductive period, for example, are recognized by many authors, published reference intervals (RIs) do not always consider these factors and, therefore, the reported RIs are wide and their diagnostic efficacy is limited. In addition, extrapolation of already established values for other species may lead to erroneous conclusions about the health status of an organism. Thus, from blood samples of a species of freshwater turtle (Phrynops geoffroanus) and of a tortoise (Chelonoidis carbonarius) this study aimed at establishing hematological and biochemical parameters and at verifying the influence of intrinsic (sex and weight/size) and extrinsic (season and environment) variables. Blood samples were obtained from males and females of P. geoffroanus, being 38 individuals sampled in the analysis of hematological parameters and 30 in biochemical parameters. As for the intrinsic factors, sex and straight carapace length (SCL) were evaluated in the hematological parameters. For biochemical parameters, the intrinsic factors were sex and body mass (MC). The blood samples of 48 adults and males C. carbonarius were obtained during the rainy season and RIs were established, as well as the effect of SCL on biochemical parameters was evaluated. The blood from P. geoffroanus was packed in a tube containing lithium heparin, for hematological tests, and in a tube containing gel and clot activator for biochemical analysis in both species. Blood smears were performed without anticoagulant. Hematological samples were refrigerated and processed within two hours of collection; and for biochemical analysis, the serum obtained by centrifugation was kept under refrigeration until processing, not exceeding 24 hours. Hematological parameters included total erythrocyte and leukocyte count; determination of packed cell volume; hemoglobin concentration, differential leukocyte count and determination of total solids. Mean corpuscular volume, mean corpuscular hemoglobin concentration and heterophil:lymphocyte ratio were also calculated. The biochemical parameters analyzed were uric acid; albumin; aspartate aminotransferase; total calcium, creatine kinase; creatinine; phosphorus; total protein, urea, calcium:phosphorus ratio and globulin value. The results and discussion of these data are presented in manuscripts contained in appendices A, B and C of this thesis.