Immune mediated haemolytic anaemia in dogs: symptoms and treatment

Immune mediated haemolytic anaemia (IMHA) is a serious autoimmune disease where a dog’s immune system mistakenly attacks its own red blood cells (RBCs), causing anaemia by reducing the blood’s ability to carry oxygen. This condition can develop suddenly and requires immediate veterinary attention.

The causes of IMHA can be divided into primary and secondary forms. Primary IMHA is when no underlying cause is found and the immune system itself initiates destruction of RBCs. Secondary IMHA is triggered by other health issues such as infections, neoplasia, reactions to medications, or, rarely, vaccination. Diagnosing IMHA involves comprehensive testing to identify the cause and to distinguish between these forms.

What is immune mediated haemolytic anaemia?

Red blood cells carry oxygen to the body’s cells and remove carbon dioxide, supporting healthy function. Anaemia occurs when the red blood cell count is abnormally low or the cells are ineffective.

In IMHA, the dog's immune system wrongly recognises its red blood cells as threats, leading to their premature destruction once released into the bloodstream. This causes symptoms linked to oxygen deficiency in the body.

Primary IMHA occurs when antibodies directly target red blood cells. Secondary IMHA arises when another condition alters the red blood cells, stimulating the immune attack.

Which dogs are more at risk?

Any dog can develop IMHA, but primary IMHA is more common in some breeds such as the Basenji puppies and certain lines of Cocker Spaniel puppies, though it is uncommon in UK Cocker Spaniel lines. Both male and female dogs across various ages can be affected equally.

Recognising symptoms of IMHA in dogs

IMHA causes a variety of symptoms, which can vary between individual dogs. Common warning signs you might notice include:

• Lethargy or reluctance to exercise
• Pale or yellow-tinged gums and eye membranes
• Rapid, shallow or uneven breathing
• Fast, weak pulse
• Loss of appetite
• Unusual eating habits, such as consuming non-food items
• Dark or bloody stools

If your dog shows these signs, prompt veterinary investigation is crucial.

How is IMHA diagnosed?

Your vet will perform a complete blood count (CBC) to confirm anaemia and check red blood cell characteristics. Additional tests may include blood smears to detect abnormal red blood cells, Coombs test to identify antibodies attached to these cells, biochemistry, and urinalysis. These help exclude secondary causes like infections or toxins.

Treatment and care for dogs with IMHA

Treatment is intensive and usually involves immunosuppressive therapies. Corticosteroids such as prednisolone are the main treatment to reduce the immune system's attack on red blood cells. If steroids alone are insufficient, additional immunosuppressive drugs may be added.

Dogs with severe anaemia may require hospitalisation for blood transfusions and supplemental oxygen to stabilise them. Treating any underlying triggers for secondary IMHA is essential for recovery.

Monitoring for complications, such as blood clots, is part of ongoing care. Side effects from medications can include increased thirst, hunger, urination, panting, lethargy, and behaviour changes, all of which should be managed closely with your vet.

What is the prognosis?

IMHA carries a guarded prognosis. Short-term mortality within two months ranges from 18% to 44%, though advances in treatment have improved outcomes. Early diagnosis and rigorous treatment greatly enhance the chance of survival.

Key advice for responsible dog owners

IMHA is a veterinary emergency; swift veterinary consultation is vital if you suspect your dog is affected. Diagnosis requires detailed testing, and treatment involves close veterinary supervision. Caring responsibly for your dog means acting promptly and following veterinary advice thoroughly.

Ongoing research in the UK, including studies at the Royal Veterinary College, aims to improve understanding and develop safer, more effective treatments for IMHA.

If you wish to find a healthy puppy or puppies from reputable breeders, always choose well-established breeders who prioritise health testing and welfare.

Summary of Immune Mediated Haemolytic Anaemia in Dogs