Hematologic Improvement in Two Dogs with Suspected Refractory Precursor-Targeted Immune-Mediated Anemia Following Romiplostim-Based Therapy

Precursor-targeted immune-mediated anemia (PIMA) refers to a chronic non-regenerative anemia that responds poorly to conventional treatments.Therapeutic options for refractory PIMA remain limited.Two dogs were diagnosed with presumptive PIMA after receiving several immunosuppressive treatments including corticosteroids, cyclosporine, mycophenolate, or intravenous immunoglobulin.None of the dogs showed a clinical response.Romiplostim (5-10 µg/kg SC weekly) and oclacitinib (0.5 mg/kg PO BID) were administered subsequently.An 8-year-old Maltese was treated with romiplostim every week, which led to an increase in hematocrit (HCT) to 26%.It was maintained for nearly two years without transfusion.A 6-year-old Poodle was treated with romiplostim and dalbepoetin alpha (1 µg/kg SC) and oclacitinib.HCT rose to 24% and reticulocyte counts remained stable even after withdrawal of treatment.The combination of romiplostim and oclacitinib may represent a novel therapeutic approach for stimulating erythroid regeneration; however, further studies are required to evaluate its efficacy and safety.