Influence of hemoparasite presence on hematological parameters in Boa constrictor: evidence of subtle erythrocyte alterations

Hemoparasites are frequently reported in reptiles, particularly snakes, where they are often considered subclinical and of limited pathological significance. However, their effects on hematological parameters remain poorly understood. This study aimed to evaluate the prevalence of hemoparasites and their influence on hematological variables in adult Boa constrictor. Blood samples were collected from 36 adult snakes of both sexes, including captive and free-living individuals, in Cuiabá, Mato Grosso, Brazil. Hematological analyses included erythrogram, leukogram, thrombocyte counts, and total solids. Blood smears stained with May–Grünwald–Giemsa were examined for hemoparasites. Generalized linear models were used to assess the effect of hemoparasite presence on hematological parameters (p < 0.05). Hemoparasites morphologically compatible with hemogregarines were detected in 44.4% (16/36) of the snakes. Their presence was associated only with increased mean corpuscular volume (MCV) (p = 0.03), with infected animals showing higher MCV values, with a mean of 432.26 and standard deviation of 43.61, compared to non-infected individuals, which presented a mean of 394.32 and standard deviation of 29.36. No significant differences were observed for RBC count, hemoglobin concentration, packed cell volume, or other hematological parameters (p ≥ 0.05). The increase in MCV, in the absence of changes in RBC count, hemoglobin concentration, and PCV, indicates no evidence of anemia or a regenerative response. Intraerythrocytic hemogregarines are known to induce enlargement of infected erythrocytes, which may contribute to increased cell volume. Thus, the higher MCV values observed are more consistent with subtle cellular alterations than with a clinically relevant pathological process. The absence of additional hematological changes suggests limited impact on erythrocyte dynamics. Overall, these findings support the subclinical nature of these infections and highlight the need for cautious interpretation of isolated hematological variations in reptiles.