Immune-mediated hemolytic anemia in dogs and cats: Comparative pathophysiology, diagnosis and management
Author(s): Abhijith SP, Apoorva HJ, Abdul Kalam A, Chandrakumar D and Sanjay HV
Abstract: Immune-mediated hemolytic anemia (IMHA) is a severe and potentially fatal hematologic disorder in which the immune system targets and destroys the body’s own red blood cells (RBCs), resulting in regenerative or nonregenerative anemia. The disease can occur as primary (idiopathic) or secondary, triggered by infections, neoplasia, drugs, or vaccines. This review aimed to summarize the current understanding of IMHA’s etiology, pathogenesis, clinical presentation, diagnostic criteria, management, and prognosis in both dogs and cats. Information was compiled from recent studies, consensus statements, and case reports, including retrospective clinical analyses and molecular investigations. IMHA is primarily mediated by autoantibodies (IgG or IgM) that promote extravascular and/or intravascular RBC destruction through phagocytosis or complement activation. Clinically, affected animals exhibit pallor, icterus, tachycardia, splenomegaly, and in severe cases, hemoglobinuria. Diagnostic evaluation includes hematology, Coombs’ testing, blood smear analysis, and molecular screening to differentiate idiopathic from secondary forms. Prognosis remains guarded, with mortality rates ranging from 18-44% within the initial months after diagnosis, primarily due to thromboembolic complications. Immunosuppressive therapy (glucocorticoids with or without adjunctive agents) forms the cornerstone of treatment, supported by blood transfusion and antithrombotic therapy. Secondary IMHA requires addressing the underlying cause, such as infection or neoplasia. Recent studies emphasize the role of genetic susceptibility, cytokine dysregulation, and complement pathways in disease progression. Future directions include the development of targeted immunotherapies, improved molecular diagnostics, and long-term monitoring tools for relapse prediction. Overall, early recognition, comprehensive diagnostic workup, and multimodal therapy significantly improve survival outcomes in dogs and cats with IMHA.
