All about IMHA in dogs

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All about IMHA in dogs

Immune-mediated hemolytic anemia (IMHA) may sound like an obscure disease, but it’s more common than you might think.

Something was wrong with Gracie. It started with subtle signs – she didn’t have her usual pep when on walks, her appetite was off, and she didn’t want to chase her favorite ball. In a few days, these subtle signs were replaced with more worrisome ones. Gracie didn’t want to get up, was breathing heavily, and her gums were pale and yellowish. A visit to the veterinarian revealed something serious – Gracie had immune-mediated hemolytic anemia, or IMHA.

What is IMHA?

Immune-mediated hemolytic anemia is a condition in which the immune system attacks normal cells – in this case red blood cells – and destroys them. It is one of many immunemediated diseases; others include lupus and immunemediated thrombocytopenia. In each disease, the underlying cause is the same: the immune system gets stimulated but then reacts abnormally, turning on the body’s own cells rather than a foreign agent. However, immune-mediated diseases can look very different depending on which cell type the immune system targets.

In IMHA, the immune system attacks red blood cells and causes them to burst. Red blood cells are vital, because they carry oxygen from the lungs to all the tissues in the body. Without these cells, the entire body gets deprived of oxygen, producing weakness and lethargy. Additionally, the destroyed red blood cells must be cleansed from the circulatory system. This job falls to the kidneys and liver. When there is suddenly a large quantity of red blood cell debris to clean up, the liver and kidneys get strained and can quickly fail.

What causes the disease?

Unfortunately, the cause is frequently never found; in fact, 60% to 75% of cases are considered idiopathic (cause unknown). But a few things are known to be potential instigators.

1. Certain drugs can lead to abnormal immune stimulation and the development of IMHA. These include antibiotics (penicillin, trimethoprim-sulfa), methimazole and acetaminophen.

2. Conditions such as cancer can over-stimulate the immune system.

3. Dogs with hemangiosarcoma are at increased risk of developing IMHA.

4. Eating inappropriate items, such as onions or coins made of zinc, can lead to this disease.

5. Certain parasites that reside in the red blood cells can create an immune response that gets out of control, resulting in IMHA.

6. Anything that stimulates the immune system could potentially lead to over-stimulation and IMHA.

7. Vaccination, or more importantly over-vaccination, has been frequently suspected as a culprit, although the jury is still out on this. Core vaccines play an important role in controlling diseases like parvovirus and distemper, so it is never a good idea to stop administering them altogether. Next time your dog is at the veterinarian’s office for a routine examination, discuss his vaccination schedule to maximize protection while minimizing potential harm.

How do I know if my dog has it?

Dogs with IMHA can often go undiagnosed for several days, because the early signs are subtle and non-specific. The dog will act lethargic – he’ll just lie around, have no energy and not engage in normal play. As the disease worsens, the lethargy will become more pronounced. Dogs may also breathe harder or pant as their ability to transport oxygen throughout the body decreases. You may notice dark orange or brown urine, and the dog’s gums will also become very pale or even white. The skin, gums and sclera (white part of the eyes) may also turn yellow; this is the result of bilirubin released from inside the red blood cells.

IMHA can be diagnosed with a thorough history, examination and a complete blood count (CBC). This test will show an extremely low number of red blood cells, or severe anemia. Further tests will confirm the diagnosis, such as the Coomb’s test and auto-agglutination test, but these are not frequently performed unless there is some doubt about the diagnosis.

What if my dog is diagnosed with IMHA? 

Conventional treatment options center around suppressing the immune system to slow or halt the destruction of red blood cells. This is most commonly achieved with one or many drugs – prednisone, azathioprine, cyclophosphamide, etc. These drugs are given at high doses for long periods of time, frequently resulting in a myriad of unpleasant side effects. Treatment can last for a year or more. Other treatments can include blood transfusions and extended hospital stays if the condition is severe. Reported survival rates are between 55% to 75%, but relapses are common.

Integrative treatment options also aim to dampen the immune response.

• A hypoallergenic diet is the first place to start. While food allergies may not have caused the IMHA, allergens in the food may cause further unnecessary stimulation to an already overstimulated immune system. Hypoallergenic diets will allow for adequate nutrient absorption without fanning the flames of an already inflamed immune system.

Probiotics are another way to help calm the immune system. Good bacteria in the gut decrease the likelihood of bad bacteria invasions, and aid the process of digestion.

• Omega-3 fatty acids, such as those found in fish oil, have been shown in several studies to have anti-inflammatory effects on many conditions, such as allergic skin disease and arthritis. Dehydroepiandrosterone (DHEA) blood levels are low in immune-related diseases. Some studies suggest that supplementation with DHEA may also help ameliorate the side effects associated with steroids.

• Several herbs have been shown to protect red blood cells and stimulate the bone marrow to produce more. These include Dong quai (Angelical sinensis) and Rhodiola (Rhodiola rosea).

IMHA can be a severe illness, and the cause is frequently never discovered. But Gracie was lucky. She received a combination of high dose prednisone, diet therapy, probiotics and herbs. Today, her CBC is normal and she is back to playing with her favorite ball.