Exotic animals pose a unique challenge for hematologic tests. This is because all of their cells in blood (red blood cells, white blood cells, and platelets – also called thrombocytes) are nucleated. Therefore, we use different methods to count these different cell types in blood and we have to be able to distinguish between them during blood smear examination, which can also be quite difficult. Some species also contain unique cell types that other species lack. For instance, reptiles have a type of mononuclear called an azurophil, which is thought to be a monocyte variant. In contrast, birds lack azurophils. The standard non-mammalian hemogram at Cornell University consists of the following results (and contains far fewer results than the equivalent mammalian hemogram):
- Red blood cells: Packed cell volume, morphologic features.
- White blood cells: White blood cell count, differential white blood cell count (neutrophil or heterophil), morphologic features.
- Thrombocytes: Estimate from a smear.
- Blood smear assessment: Morphologic features of all the hematopoietic cells and checking for those infectious agents.