Long-Term Case Study of Atypical Myelodysplastic Syndrome with Excess Blasts Presenting with Neutrophilia and Thrombocytosis in a Dog

Myelodysplastic syndrome with excess blasts (MDS-EB) is rare in dogs but typically carries a poor prognosis and lacks a well-established treatment protocol. A 9-year-old spayed female Bichon Frisé presented with progressive weight loss and anorexia and was diagnosed with nonregenerative anemia. Infectious, inflammatory, and metabolic causes of anemia were ruled out. Cytologic evaluation and bone marrow histopathology revealed orderly maturation across all hematopoietic lineages and moderate dysplasia in both the erythroid and megakaryocytic cell lines. Dysplasia involving multiple hematopoietic lineages, along with the presence of 10-15% blasts, confirmed a diagnosis of MDS-EB. Following diagnosis, the dog was managed with immunosuppressive therapy combining prednisolone, mycophenolate mofetil, and cyclosporin, as well as periodic blood transfusions. Despite the generally poor prognosis associated with MDS-EB, this patient survived for 460 days post-diagnosis, which is an atypically long survival period for cases of this condition.