Cytologic and Cytochemical Characterization of Blue-Green Neutrophilic Inclusions in a Dog with Suspected Transfusion-Associated Hemolysis.

An 11-year-old castrated male Maltese dog presented with acute lethargy and non-regenerative anemia. Despite immunosuppressive therapy and an initial packed red blood cell (pRBC) transfusion, hematocrit levels progressively declined after transient improvement. A second transfusion was administered following compatible crossmatch testing. Within 24 h of the second transfusion, a transfusion-associated hemolytic episode was suspected due to a rapid hematocrit decline, pigmenturia, hyperbilirubinemia, and autoagglutination. Peripheral blood smear revealed neutrophils containing coarse blue-green cytoplasmic inclusions. Special staining and autofluorescence microscopy supported lipid-rich, acid-fast, and autofluorescent properties of the inclusions. Prussian blue staining showed iron-positive granular material in the hemolytic sample, but the intraneutrophilic inclusions did not show distinct Prussian blue reactivity, making hemosiderin-rich sideroleukocytes unlikely to fully explain the findings. Similar inclusions have recently been characterized in dogs, mainly in association with severe hepatocellular injury, pancreatitis, and poor short-term outcomes; however, their occurrence during acute clinical deterioration associated with suspected post-transfusion hemolysis has not been specifically documented. The dog died three days after inclusion detection. This case expands the clinical settings in which blue-green leukocyte cytoplasmic inclusions may be encountered in dogs.