IMHA
IMMUNE-MEDIATED HEMOLYTIC ANEMIA or IMHA
DID YOU KNOW THAT…
Anemia means that the level of red blood cells is abnormally low. The main function of red blood cells is the transport of oxygen to the different tissues of the body. If the patient is anemic, his tissues are insufficiently oxygenated.
Hemolytic anemia means that low red blood cell counts are caused by the destruction (lysis) of red blood cells. And finally the term “immune-mediated” indicates that it is the immune system which is at the origin of the destruction of red blood cells.
When the immune system functions normally, it is able to recognize “bad” elements that need to be destroyed, such as during an infection. In the case of immune-mediated hemolytic anemia (IMHA), the immune system mistakenly categorizes healthy red blood cells as elements that must be destroyed to protect the body.
CAUSES AND DEVELOPMENT
This dysfunction of the immune system can develop for no apparent reason (primary or idiopathic IMHA) or can be caused by an element (secondary IMHA). In theory, any infection, inflammation or tumor can trigger a dysfunction of the immune system. However, it is sometimes difficult to prove that there is a causal link between the two issues.
The Cocker Spaniel is predisposed to primary IMHA.
CLINICAL SYMPTOMS
The symptoms are secondary to the presence of anemia. Pale mucous membranes, weakness, intolerance to exercise and rapid breathing are often observed. In some cases, the mucous membranes become yellowish (jaundice) and/or the urine takes on a red-brown color if the liver is in pain.
Depending on the speed and severity of red blood cell destruction, the animal may require urgent care to be stabilized with a red blood cell transfusion.
DIAGNOSIS
The first step is to determine the cause of the anemia. Certain blood tests (auto-agglutination on a slide, Coomb’s test, presence of spherocytes in blood smear) make it possible to demonstrate the involvement of the immune system in the destruction of red blood cells.
The next step is to determine whether the IMHA is primary or secondary. Various additional examinations can therefore be considered to look for an underlying cause: complete blood test, ultrasound of the abdomen, chest x-rays, specific search for infectious agents, etc.
In some cases, the immune system attacks the blood cell precursors (young red blood cells that have not yet matured) found in the bone marrow before they have had time to be released into the blood circulation. In this case, a bone marrow analysis is recommended. This form of IMHA is more common in cats.
TREATMENTS AND PROGNOSIS
Treatment depends on the underlying cause. If no cause could be identified, immunomodulatory treatment (drugs that modulate the immune system) is implemented. If an underlying cause is identified or suspected, it is treated and the response to treatment is assessed by monitoring the red blood cell count.
In dogs, primary IMHA is more frequently diagnosed than secondary IMHA. Immunomodulatory treatment (corticosteroids) is therefore often necessary.
In certain cases, immunomodulatory treatment can be gradually reduced and stopped after several months; however, relapses may occur. Other cases require lifelong treatment.
Support with Hepa Supp™ and Anti-Ox™ is very helpful.
Dr Emilie Vangrinsven
Diplomate from European college of veterinary internal medicine | PhD U-Liège
Assistant at the Liege University in the university clinic for PETs | Author and co-author of numerous scientific publications
