Case report links blue-green neutrophil inclusions to canine hemolysis

Version 2 — Full analysis

A newly published case report in Veterinary Sciences spotlights an unusual blood smear finding in a dog with suspected transfusion-associated hemolysis: blue-green cytoplasmic inclusions in neutrophils. The patient, an 11-year-old castrated male Maltese, presented with acute lethargy and non-regenerative anemia, underwent immunosuppressive treatment and transfusion support, and then deteriorated after a second packed red blood cell transfusion despite compatible crossmatch testing, according to the report summary provided by the journal source. The episode was marked by rapid hematocrit decline and signs consistent with hemolysis, including pigmenturia and hyperbilirubinemia. (merckvetmanual.com)

The case lands in a niche but clinically relevant area of veterinary pathology. Blue-green leukocyte inclusions have been described far more often in human critical care, where they are associated with severe systemic illness and liver injury. In dogs, the literature is still sparse, but a 2024 canine study found that blue-green blood leukocyte inclusions had stained and unstained properties consistent with lipofuscin and suggested the presence of hepatocellular injury, often severe. A recent feline case report published in September 2026 also tied similar neutrophilic inclusions to severe hepatocellular injury, suggesting the phenomenon may be gaining broader recognition across small animal medicine. (pubmed.ncbi.nlm.nih.gov)

That background matters because the new report appears to connect two high-risk processes that clinicians may not usually link on first pass: transfusion-associated hemolysis and pigment-laden leukocyte inclusions. Standard veterinary transfusion references note that acute hemolytic transfusion reactions in dogs are typically recognized by an inadequate post-transfusion PCV rise plus evidence of hemolysis, such as new hyperbilirubinemia, hemoglobinemia, or hemoglobinuria. The broader canine transfusion literature also shows that acute hemolytic reactions can occur in dogs with no obvious pretransfusion intravascular hemolysis and that reaction rates vary substantially by study design and case mix. (merckvetmanual.com)

One of the more important takeaways is that compatible testing did not rule out trouble. The Association of Veterinary Hematology and Transfusion Medicine’s consensus guidance says crossmatching reduces risk, but does not eliminate the possibility of hemolytic reactions, and specifically notes that use of the same compatible donor does not guarantee compatibility for a subsequent transfusion. The consensus literature also points to sensitization against unidentified or less routinely characterized canine red cell antigens as a possible explanation in some cases. That makes this report less of an outlier than it may first appear, especially in dogs needing repeat transfusions. (onlinelibrary.wiley.com)

Outside reaction-specific guidance, the case also reinforces the diagnostic value of manual smear review. Educational and review sources in veterinary clinical pathology note that blue-green inclusions in canine neutrophils may represent different pigment processes, including hemosiderin in some hemolytic settings and lipofuscin-like material in dogs with acute hepatocellular necrosis. The 2024 canine characterization study leaned toward a lipofuscin association and linked the finding to severe liver injury. Taken together, the available evidence supports a cautious interpretation: these inclusions are probably not disease-specific, but they may be a red flag for severe pigment processing, hepatocellular damage, or both in unstable patients. That last point is an inference from the current literature, rather than a settled conclusion. (todaysveterinarypractice.com)

Why it matters: For veterinarians, emergency clinicians, internists, and clinical pathologists, the report is a practical reminder that post-transfusion deterioration deserves a broad but disciplined workup. If a dog shows a poor hematocrit response after transfusion, new bilirubin elevation, pigmenturia, or smear abnormalities, clinicians may need to think beyond simple progression of underlying anemia and consider transfusion reaction, storage-related red cell injury, occult incompatibility, or concurrent hepatic injury. The case also supports keeping blood smear review in the workflow even when analyzers and standard chemistry panels are available, because rare morphologic findings may sharpen triage and prognosis. (pmc.ncbi.nlm.nih.gov)

There does not appear to be a separate institutional press release or broad industry commentary on this report, which is typical for a single case study. Still, the surrounding expert literature is consistent on the larger message: transfusion medicine in dogs is safer than it once was, but not fail-safe, and uncommon smear findings can carry disproportionate clinical value. As more case reports accumulate, the field should get a better read on whether blue-green neutrophilic inclusions are mainly markers of severe hepatocellular injury, markers of hemolysis-related pigment burden, or a convergence of both in critically ill dogs. (avhtm.org)

What to watch: The next thing to watch is whether future reports pair these inclusions with liver histopathology, bile pigment studies, or serial post-transfusion immunohematology, which could help define mechanism and determine whether the finding has prognostic value in canine transfusion cases. (pubmed.ncbi.nlm.nih.gov)