Immune-Mediated Haemolytic Anaemia in Dogs: Welfare Guide
Disease Overview
Immune-mediated haemolytic anaemia (IMHA) occurs when the immune system produces antibodies against the dog's own red blood cells, causing their destruction (haemolysis). It can be primary (idiopathic) or secondary to triggers including drugs, infections, or neoplasia. Cocker Spaniels, English Springer Spaniels, and Old English Sheepdogs are predisposed breeds. It is a serious, potentially fatal condition with mortality rates of 30-70% even with treatment.
Welfare Consequences
IMHA causes severe anaemia: profound weakness, exercise intolerance, pallor or jaundice, rapid heart rate, and respiratory distress. Dogs may collapse and become profoundly depressed. Thromboembolism (blood clots forming due to immunological disruption) is a major complication causing acute respiratory distress, sudden death, or limb ischaemia. Hospitalisation with intensive monitoring is required, involving repeated blood tests, IV lines, and prolonged treatment — all with welfare implications.
Diagnosis
Complete blood count shows severe anaemia with regenerative response (if the bone marrow is functioning) or non-regenerative anaemia (if bone marrow erythropoiesis is also targeted). Blood smear shows spherocytes and agglutination. Coombs test (direct agglutination test) detects anti-red blood cell antibodies. Assessment for secondary causes (tick-borne disease serology, thorough examination) is important. Concurrent thrombocytopenia suggests Evans syndrome.
Treatment
Immunosuppression is the cornerstone of treatment: high-dose prednisolone is first-line. Additional immunosuppressants (azathioprine, ciclosporin, mycophenolate mofetil) are used in refractory cases. Thromboprophylaxis with low-dose aspirin, clopidogrel, or low-molecular-weight heparin reduces thromboembolic risk. Blood transfusion may be required for severe anaemia. The first 2 weeks of treatment are highest risk; response to treatment guides long-term management.
Long-term Welfare and Relapse
Immunosuppressive drugs are tapered slowly over months once remission is achieved, guided by packed cell volume monitoring. Relapse is common (30-40% of cases). Owners require education about relapse signs and the importance of medication compliance. Long-term immunosuppression carries risks: infection susceptibility, diabetes mellitus (corticosteroid-induced), hepatopathy, and GI ulceration. Regular monitoring minimises long-term drug side effects. Dogs in remission can have excellent quality of life.