Immune mediated hemolytic anemia (or IMHA, for short) is a life-threatening blood disorder. To understand this long-named disease, let’s break it down into parts:

Immune mediated = the immune system malfunctions, and begins destroying cells in the body

Hemolytic = breakdown of red blood cells

Anemia = low levels of hemoglobin and red blood cells

Put them all together, and you’ve got a condition in which an overactive immune system targets too many red blood cells for destruction, resulting in moderate to severe anemia.

The purpose of red blood cells

Red blood cells serve a vital function, delivering oxygen from the lungs to all of the tissues of the body. They have a natural life span of about two months in cats and three months in dogs. In a normal animal, red blood cells are removed as they circulate through the spleen, liver and bone marrow about as fast as they are made, so the total number of red blood cells stays level.

When an animal has IMHA, the body’s immune system marks too many red blood cells for removal. Over time, so many red blood cells are destroyed that there aren’t enough in circulation to perform their job delivering oxygen to vital tissues.

IMHA may have an underlying cause, or it may not. In 60 percent to 75 percent of IMHA cases in dogs, an underlying cause is never found. In cats, IMHA is generally caused by feline leukemia or by a blood parasite called Mycoplasma hemofelis.

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Symptoms of immune mediated hemolytic anemia

Symptoms of IMHA are due to the anemia. You’ll notice your pet becoming lethargic and weak, and the gums and lips may become pale. You may also notice jaundice, or a yellowing of the gums and whites of the eyes. Urine may contain the breakdown products from the red blood cells, so it may be orange or brown in color.

Your veterinarian will use a blood test to diagnose IMHA, and she will likely want to perform other tests as well. By looking at your pet’s blood sample microscopically, she may be able to find other clues, like misshapen red blood cells, cells that clump together, or the presence of immature red blood cells. Finally, she may send off a Coomb’s test, which looks for antibodies on the red blood cells.


Treatment of IMHA centers on suppressing the body’s inappropriate immune response. If the immune system can be quieted, red blood cells will stop being targeted for destruction. High-dose steroids are used to suppress the immune system. If ineffective, other more potent immunomodulators will be considered. In the meantime, other supportive treatment, like IV fluids and nutritional support, will be provided.

Many patients with IMHA will find their anemia severe enough to require blood transfusions. If you haven’t already guessed, IMHA is serious and often requires lengthy hospitalization. Having dog pet insurance with Petplan can provide you with peace of mind that your pet's stay in the hospital, as well as any necessary treatments, can be covered.

Once your pet is feeling better, you’ll be sent home with orders to continue your pet’s steroids, which you’ll slowly taper off over weeks or months. During this time, you will likely have several rechecks to make sure your pet is on the right path. It’s important to be vigilant during this rocky time – be sure to report any setbacks your pet may have while her medication is being tapered.

Dec 28, 2012
Pet Health

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