ABSTRACT
BACKGROUND: The Asian water monitor (Varanus salvator) is the most common monitor lizard in Thailand. Reported data regarding hematology and morphology of blood cells for this species are scarce. OBJECTIVES: The objective of this study was to assess routine hematologic variables and characterize the morphology, cytochemical staining, and ultrastructural features of blood cells in the Asian water monitor. METHODS: Blood samples from 55 monitors (22 males and 33 females) were obtained for a CBC. Cytochemical staining (Sudan black B [SBB], peroxidase [PO], α-naphthyl acetate esterase [ANAE], and beta-glucuronidase [BG]), and scanning and transmission electron microscopy were performed using standard methods. RESULTS: Determined mean (range) hematologic results of all monitors included PCV 0.32 L/L (0.20-0.44 L/L), HGB 106 g/L (62-157 g/L), WBC 15.9 × 10(9) /L (4.0-34.0 × 10(9) /L), heterophil 6.3 × 10(9) /L (1.5-17.1 × 10(9) /L, azurophil 2.6 × 10(9) /L (0.7-9.5 × 10(9) /L), basophil 0.1 (0.1-0.5 × 10(9) /L), lymphocyte 6.8 × 10(9) /L (0.5-13.1 × 10(9) /L), and monocyte 0.2 × 10(9) /L (0.04-1 × 10(9) /L) counts. Heterophils and basophils stained strongly positive with SBB, ANAE, and BG. Heterophils contained 2 types of granules, round SBB-positive and PO-negative granules, and electron-dense, large rod-shaped granules. Gamonts of Hepatozoon sp. were found in <1% RBC of 43 monitors. There was no significant difference between hematologic variables in Hepatozoon-positive and -negative monitors. CONCLUSION: Heterophils in Asian water monitors may also function as eosinophils based on cytochemical and ultrastructural features. The quantitative results may be used as base for further studies in healthy and diseased Asian water monitors.
