Immune-mediated haemolytic anaemia (IMHA) is a serious disease that mainly affects dogs, although it can also affect cats. This autoimmune condition causes the immune system to attack and destroy the animal’s red blood cells, leading to debilitating symptoms and can be fatal in severe cases without adequate treatment.
What causes this disease?
Immune mediated haemolytic anaemia (IMHA) results from a malfunction of the immune system which produces abnormal antibodies, called autoantibodies, and attacks the animal’s red blood cells. Although the exact cause of this autoimmune reaction is often unknown, several triggering factors include viral infections, taking certain medications, or association with other autoimmune diseases such as lupus. In dogs, certain breeds, such as Cocker Spaniels, Labradors and Bichon Frise, show an increased predisposition to this disease, suggesting a genetic component.
AHMI can be divided into two categories according to the type of antibodies involved: ‘hot’ autoantibodies, which are active at temperatures between 37 and 40°C, and ‘cold’ autoantibodies, which are active at temperatures below 30°C. IMHA with “hot” autoantibodies is the most common, accounting for around 70% of cases.
Veterinarians also identify certain underlying causes, such as bacterial infections (e.g.ehrlichiosis or babesiosis), neoplasia (notably lymphoma orhaemangiosarcoma), or exposure to toxins. In rare cases, the disease may be hereditary, linked to abnormalities in haemoglobin or the membrane of red blood cells.
It is essential to note that AHMI is not a contagious disease, and can affect dogs and cats of any age, although certain breeds are more likely to develop the condition.
What are the symptoms of immune mediated haemolytic anaemia (IMHA)?
The symptoms ofimmune-mediated haemolytic anaemia (IMHA) in animals are varied and can manifest themselves in different ways. The most frequent clinical signs are linked to a reduction in the number of red blood cells, leading to anaemia and its consequences. Shortness of breath, even with minor exertion, paleness of the mucous membranes and general tiredness are often observed. These signs are directly linked to the inability of the blood to transport oxygen efficiently throughout the body.
In parallel, symptoms linked to the increased destruction of red blood cells, a process known as haemolysis, may include a yellowish discolouration of the skin and conjunctivae, known asjaundice, and dark urine, often with a reddish or brown tinge. The accumulation of bilirubin, a pigment produced when red blood cells are destroyed, causes these signs.
Other symptoms may include vomiting, diarrhoea, increased water consumption and urine output, and in some cases fever. In severely affected animals, kidney failure may develop due to the accumulation of toxins in the body. Destruction of blood platelets (thrombocytopenia) is also possible, which can lead to bleeding from the mucous membranes.
Physical examination may reveal pale mucous membranes, increased heart and respiratory rates, and enlargement of the spleen and liver. To sum up, the symptoms of AHMI are mainly related to anaemia, haemolysis and the secondary complications that may arise.
How is it diagnosed?
The diagnosis ofimmune-mediated haemolytic anaemia (IMHA) is based on a series of tests and medical examinations aimed at identifying the underlying cause of the anaemia and ruling out other potential pathologies. The first step is a blood test to detect a drop in haemoglobin levels and confirm the presence of anaemia. This analysis can also identify signs of haemolysis, such as increasedhaptoglobin and the presence of reticulocytes, which are young red blood cells, indicating that the bone marrow is trying to compensate for the destruction of erythrocytes.
The Coombs test is a key test for confirming the diagnosis of IHA. This test detects the presence ofautoantibodies directed against red blood cells. A positive Coombs test result indicates that the immune system is attacking the red blood cells, which is characteristic of AHMI.
To differentiate AHMI from other causes of anaemia and jaundice, additional tests such ashaematology, biochemistry, urinalysis and coagulation profiles are required. These tests are used to check the animal’s general condition and identify any complications, such as coagulation problems or the presence of blood parasites.
Veterinary surgeons usemedical imaging (X-rays and ultrasound scans) to look for signs of neoplasia or other underlying pathologies that may triggerIHA. In some cases, a bone marrow biopsy is performed toassess blood cell production andrule out bone marrow disease.
Finally, clinicians diagnoseprimary AHMI by exclusion, after ruling out all other possible causes.
What treatments are available?
The mainstay of treatment forimmune-mediated haemolytic anaemia (IMHA) is the administration of immunosuppressive drugs to reduce the excessive activity of the immune system. Corticosteroids, such as cortisone, are commonly used as the first line of treatment. Around 80% of animals respond favourably to this type of treatment. When corticosteroids are not sufficient, other immunosuppressants may be prescribed to control the disease.
In severe cases where the anaemia is severe and poorly tolerated, blood transfusions may be necessary to stabilise the animal until the medication takes effect. These transfusions temporarily restore the number of red blood cells and improve the body’s oxygen-carrying capacity.
Regular intake of vitamin B9 (folates) is also recommended to support the rapid production of new red blood cells by the bone marrow. If there is an underlying cause ofIHA, it should be treated as a priority. For example, if there is an infection or cancer associated with the disease, administer the treatments in parallel to maximise the chances of success againstIMHA.
Vets will sometimes consider splenectomy (removal of the spleen), despite the fact that this is a cumbersome procedure and carries significant risks. Younger dogs generally have a more favourable prognosis, with an average survival time of almost three years for those who survive beyond the first two months after diagnosis.
It is important to note that even with adequate treatment, the mortality rate in dogs with IHA remains high, ranging from 40% to 60%. Regular monitoring and ongoing adaptation of treatment according to the animal’s response are essential for the long-term management of this disease.
What are the natural alternatives?
Diet plays a key role in supporting the immune system and the production of red blood cells. It is advisable to provide the animal with a diet rich in essential nutrients, particularly B vitamins, iron and antioxidants. Food supplements based on spirulina, chlorella or vitamin C can help boost the immune system and improve the animal’s general health.
Finally, energy rebalancing, through therapies such asacupuncture orhomeopathy, is sometimes used to complement conventional treatments. These approaches aim to restore the animal’s energy balance and stimulate its natural healing capacities.
It is important to consult a vet before introducing any natural therapy into the treatment of IHA, to ensure that it is safe and appropriate for the animal’s state of health.
