Quantitative and qualitative morphologic, cytochemical, and ultrastructural characteristics of blood cells in captive Asian water monitors

BackgroundThe 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.ObjectivesThe 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.MethodsBlood samples from 55 monitors (22 males and 33 females) were obtained for aCBC. 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.ResultsDetermined mean (range) hematologic results of all monitors includedPCV0.32 L/L (0.20–0.44 L/L),HGB106 g/L (62–157 g/L),WBC15.9 × 109/L (4.0–34.0 × 109/L), heterophil 6.3 × 109/L (1.5–17.1 × 109/L, azurophil 2.6 × 109/L (0.7–9.5 × 109/L), basophil 0.1 (0.1–0.5 × 109/L), lymphocyte 6.8 × 109/L (0.5–13.1 × 109/L), and monocyte 0.2 × 109/L (0.04–1 × 109/L) counts. Heterophils and basophils stained strongly positive withSBB,ANAE, andBG. Heterophils contained 2 types of granules, roundSBB‐positive andPO‐negative granules, and electron‐dense, large rod‐shaped granules. Gamonts ofHepatozoonsp. were found in <1%RBCof 43 monitors. There was no significant difference between hematologic variables inHepatozoon‐positive and ‐negative monitors.ConclusionHeterophils 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.