Immune-mediated hemolytic anemia (IMHA) is a serious disorder in which the immune system destroys the body's own red blood cells, causing rapid, sometimes severe anemia. It may be primary (idiopathic) or triggered by infections, drugs, toxins, or cancer. IMHA is a medical emergency with a guarded prognosis and high risk of fatal blood clots.
IMHA is one of the most common and life-threatening immune disorders in dogs. The immune system mistakenly attacks red blood cells, leading to their premature destruction and anemia that can develop within days.
Many cases are primary with no identifiable trigger. Secondary cases follow infections, certain drugs, vaccines, toxins, parasites, or underlying cancers.
Owners notice pale or yellow gums, weakness, rapid breathing, lethargy, and dark or orange urine. Collapse can occur with severe anemia or a blood clot.
Bloodwork shows anemia with evidence of red cell destruction and regeneration. Tests such as a saline agglutination test, Coombs test, and screening for triggers help confirm the diagnosis and identify causes.
Treatment centres on immunosuppression with corticosteroids, often combined with additional immune-modulating drugs. Blood transfusions, clot-prevention medication, and intensive supportive care are frequently needed.
Primary IMHA cannot be prevented. Avoiding unnecessary drugs in susceptible dogs and prompt treatment of infections may reduce secondary cases.
This content is for educational purposes and is not a substitute for professional veterinary advice. If you are worried about your pet, contact your veterinarian.
