Hematology and Plasma Biochemistry Reference Values of the Subgenus Hapturosaurus (Varanus macraei, Varanus prasinus, Varanus beccarii) Under Human Care

Abstract

Simple Summary: Tree monitor lizards of the Hapturosaurus group are becoming increasingly common in zoos, but there is little scientific information to guide veterinarians in assessing their health. This study aimed to establish initial blood reference intervals in three species of these lizards: the green tree monitor, the black tree monitor and the blue tree monitor. Blood samples from healthy adult animals kept in controlled conditions were carefully analyzed. The results included measurements of hematology and biochemistry parameters. No significant differences were found between the three species, allowing the results to be combined for stronger conclusions. By having reference values for key health parameters following the guidelines provided by the American Society for Veterinary Clinical Pathology (ASVCP), veterinary professionals can identify health issues at an earlier stage, thereby improving the overall care and management of these animals. Additionally, this research supports conservation efforts by aiding zoos and captive breeding centers in maintaining healthy populations of tree monitor lizard species, many of which are threatened in their natural habitats.

Abstract: The tree monitor lizards of the subgenus Hapturosaurus are an understudied but increasingly important group of reptiles in zoos. The routine blood analysis of reptiles in captivity is highly recommended; however, the lack of reliable reference values for many species severely limits their clinical use. This study aims to establish preliminary reference values (RV) for the main hematological and biochemical parameters in three species of the subgenus Hapturosaurus (Varanus macraei, Varanus prasinus and Varanus beccarii). Blood samples were taken from healthy adult individuals (n = 34), females (n = 18) and males (n = 16), maintained under controlled conditions in a zoo. A complete biochemical analysis was performed on all individuals, including alanine-aminotransferase, alkaline phosphatase, gamma-glutamyl transpeptidase, aspartate-aminotransferase, creatine kinase, bile acids, urea, uric acid, total solids, total proteins, albumin, glucose, fructosamine, lactate, cholesterol, triglycerides, amylase, calcium, phosphorus, calcium:phosphorus ratio, and magnesium. In addition, a complete hematological analysis was conducted on these individuals, including hematocrit, hemoglobin concentration, total erythrocyte and leukocyte counts, and leukocyte differential count. From the data obtained, reference intervals were established following the guidelines provided by the American Society for Veterinary Clinical Pathology (ASVCP). In this study, the results of the three species were unified to increase the sample size and to obtain more representative reference intervals. This unification was supported by a statistical analysis using the one-factor ANOVA test, which showed no statistically significant differences between species (p < 0.050). These data constitute an essential first step for the clinical practice and management of these Hapturosaurus species in zoos and specialized centers. Future collaboration with other institutions will help expand the dataset and enhance the accuracy of the established reference values.