Autoimmune haemolytic anaemia (AIHA) in dogs: treatment & prognosis

Autoimmune haemolytic anaemia (AIHA) in dogs is a medical emergency. The disease destroys red blood cells – and often faster than you can react. We explain here as concretely as possible what lies behind it, how vets proceed and what the diagnosis means for those affected.

What is autoimmune haemolytic anaemia?

An autoimmune haemolytic anaemia – AIHA for short, sometimes also called IMHA (immune-mediated haemolytic anaemia) – is a severe disease of the immune system. The core drama: The body attacks its own red blood cells (erythrocytes) and destroys them. The result is anaemia, i.e. blood deficiency – and this can become life-threatening.

What exactly happens in the body?

Under normal circumstances, the immune system recognises foreign invaders such as bacteria or viruses and renders them harmless. The body’s own cells are spared. In AIHA, this mechanism goes awry:

• The immune system produces antibodies that attach themselves to the dog’s red blood cells like tiny ‘markers’.
• These antibodies incorrectly classify the body’s own blood cells as ‘foreign’.
• Other cells – for example in the spleen, liver or in the bloodstream itself – then recognise the marked erythrocytes as ‘to be destroyed’.
• The red blood cells are destroyed. This process is called haemolysis.
• Because more and more of them are broken down, the blood simply can no longer transport enough oxygen. That is the anaemia.

Forms and causes of autoimmune haemolytic anaemia

Not all AIHA cases are the same. Medically, two main forms are distinguished – and the difference is crucial for treatment.

1. Primary (idiopathic) autoimmune haemolytic anaemia

Here, the cause is simply unknown. The immune system attacks the body’s own blood cells – why exactly is not yet fully understood despite research. What veterinary medics observe: certain breeds are more prone to illness. Cocker Spaniels, Poodles and Collies regularly appear on the list. A genetic or immunological malfunction is suspected.

2. Secondary autoimmune haemolytic anaemia

This form arises as a reaction to something else – a disease, a trigger from outside. Possible causes:

• Infections, especially tick-borne diseases such as babesiosis or ehrlichiosis
• Tumour diseases
• Side effects of certain medications or – in rare cases – reactions to vaccinations
• Severe inflammation or other autoimmune diseases

The immune system reacts to the actual trigger and inadvertently also hits the red blood cells. Collateral damage, so to speak.

Symptoms of autoimmune haemolytic anaemia

The symptoms can vary – depending on how quickly and how strongly the haemolysis proceeds. Common signs:

• Pale or yellowish mucous membranes (for example on the gums)
• Fatigue and general weakness
• Rapid breathing or heart rate
• Fever
• Dark urine (due to breakdown products of red blood cells)
• In severe cases, circulatory problems and collapse

It is clear: with such signs, a vet should be consulted as quickly as possible. Waiting is not an option here.

Diagnosis of autoimmune haemolytic anaemia in dogs

The diagnosis of AIHA is based on a combination of clinical examination and targeted laboratory tests. A single test is usually not sufficient.

Typical diagnostic steps

• Blood count and laboratory values: The vet checks whether the red blood cell count has dropped and whether values indicate active haemolysis – for example, an elevated bilirubin level or a changed reticulocyte count.
• Coombs test (direct antiglobulin test): Shows whether antibodies are attached to the red blood cells. A positive result is a strong indicator of AIHA.
• Blood smear under the microscope: The shape of the erythrocytes can provide clues – deformed or broken cells indicate haemolysis.
• Search for triggers: To avoid missing secondary AIHA, further tests are carried out: blood tests for infectious diseases, ultrasound, X-rays, and a detailed medical history regarding medications and vaccinations.

Speed is crucial. The earlier the diagnosis is established, the sooner treatment can begin.

Treatment of autoimmune haemolytic anaemia in dogs

The goal is clear: Stop the destruction of red blood cells, suppress the immune system and, if possible, eliminate the triggering factor. That sounds straightforward – but in practice it often isn’t.

Immunosuppressive medications

The first-line treatment is corticosteroids, usually prednisolone. They dampen the immune response and reduce antibody production. If a dog does not respond sufficiently, further active ingredients are added – such as azathioprine or cyclosporine. However, several of these medications have significant side effects that must be closely monitored.

Treatment of the underlying disease

In secondary AIHA, the rule is: if you do not treat the trigger, you are only fighting the symptoms. An infection must be treated, triggering medications must be discontinued. Without this, the actual cause remains.

Supportive measures

• Blood transfusions: In acute cases, they can be life-saving. They improve oxygen transport immediately – thus bridging the critical phase.
• Fluid therapy and circulatory stabilisation in the veterinary clinic.
• Gastric protection and thrombosis prophylaxis – because AIHA patients have an increased risk of blood clots.

Long-term management

When the blood values stabilise, the medications are gradually reduced. Regular blood tests are part of this – they help to detect relapses or side effects early, before they become a problem.

Prognosis for autoimmune haemolytic anaemia

First things first: An AIHA is always an emergency. The prognosis is serious, and this should not be sugar-coated. The earlier the therapy begins, the greater the chances of survival.

Acute cases

The mortality rate is high – especially in the first days to weeks after diagnosis. Even with intensive treatment, not every dog survives this phase.

Stabilised cases

If the treatment takes effect, dogs can live a good life for many months or even years. This is no exception – it is a realistic goal.

Risk of relapse

Relapses can occur particularly with primary AIHA. Long-term monitoring is therefore not a luxury, but necessary.

FAQ: Frequently asked questions about AIHA in dogs

Can autoimmune haemolytic anaemia occur suddenly?

Yes. The disease can develop within a few days, often without any recognisable warning signs. This makes it so dangerous.

How do I recognise whether my dog has autoimmune haemolytic anaemia?

Early signs are pale or yellowish mucous membranes, weakness, rapid fatigue, dark-coloured urine and accelerated breathing. If in doubt, go to the vet immediately – do not wait until the next day.

Is autoimmune haemolytic anaemia curable?

Primary AIHA is not curable, but can be controlled with medication. The secondary form can heal if the triggering cause is successfully treated.

What is the prognosis for autoimmune haemolytic anaemia?

The first few days are critical. If the dog survives this phase and responds to therapy, the chances of a longer life are good. However, relapses are possible and must be taken into account.

What are the side effects of medications against AIHA?

Corticosteroids and other immunosuppressants can cause increased appetite, excessive thirst, weight gain, increased susceptibility to infections and gastrointestinal problems. In the long term, liver damage or muscle wasting is also possible – which is why regular check-ups are so important.

Is autoimmune haemolytic anaemia contagious?

No. AIHA is not an infectious disease and is not contagious. It arises from a misguided reaction of the body’s own immune system.

Can autoimmune haemolytic anaemia be the result of a vaccination?

In rare cases, yes. Vaccinations can trigger an AIHA or favour a flare-up – especially if the dog’s immune system is already weakened. This is not an argument against vaccinations in general, but a reason to carefully check the animal’s health status before every vaccination.

Which breeds are particularly at risk?

Cocker Spaniels, English Springer Spaniels, Poodles and Collies seem to have an increased risk. This does not mean that other breeds cannot become ill – but with these dogs, special attention is worthwhile.

What does the treatment of AIHA cost?

The costs vary greatly. In the acute phase, they are often between 1,000 and 3,000 CHF. Long-term therapy, regular blood tests and possible relapses add to this. Anyone without pet insurance should prepare for considerable expenses.

Does my vet costs insurance cover the treatment of AIHA?

Many insurers cover the costs – provided that the illness was not already known as a pre-existing condition. The exact terms are in the contract documents. In case of doubt, ask the insurer directly before the first treatment begins.