- Immune-mediated hemolytic anemia (IMHA) occurs when antibodies and complement molecules of the immune system target RBCs for destruction via macrophage phagocytosis in the spleen or liver (extravascular hemolysis) or complement-mediated cytolysis within the circulation (intravascular hemolysis).1
- IMHA can be an idiopathic autoimmune event (primary IMHA) or associated with trigger factors (secondary IMHA).
- It can be the sole immune event or occur with other immune-mediated processes (eg, immune-mediated thrombocytopenia [IMTP]).2
- The condition reflects abnormal function of the immune system expressed by targeted destruction of one part of the hematopoietic system (erythroid lineage).
- Subsequently, the effects of hemolytic anemia involve many body systems.
- Primary idiopathic canine IMHA has a clear genetic basis as shown by distinct breed and familial clustering.
- Studies of genomic variation in affected versus normal dogs of predisposed breeds are currently being conducted.3
- IMHA is the most common immune-mediated disease of dogs.
- There are no true prevalence data, but most generalists should expect to see this disease at least once a year.
- Canine IMHA occurs globally.
- In parts of the world where arthropod-borne infections are endemic, the disease is more often secondary.4