Immune Mediated Hemolytic Anemia (IMHA)

Most people have heard the term “anemia”, either referred to in humans or animals.  Anemia is a condition that occurs when the number of red blood cells in the body falls below the normal values, or they function improperly.  The red blood cells serve the function of carrying oxygen to the cells in the body and picking up carbon dioxide.  Therefore, when any anemic conditions arise, it is very serious and often life-threatening as the body is not able to carry adequate oxygen or remove waste products.  One of the most common diseases of anemia in dogs and cats is IMHA.

Immune mediated hemolytic anemia (IMHA), also referred to as autoimmune hemolytic anemia, is an immune system disease in which the body attacks and destroys its own red blood cells.  Meanwhile, the body is still producing red blood cells in the bone marrow, but once they are released into circulation, the immune system again destroys them.  This disease can be diagnosed in both dogs and cats, and in two different forms:  primary and secondary.  With primary IMHA, the immune system will mistakenly produce antibodies that will attack its own red blood cells.  With secondary IMHA, the surface of the red blood cell is modified by an underlying disease, drug, or toxin and the immune system identifies it as foreign and destroys it.  When too many of the red blood cells are destroyed and not replaced quickly enough, the animal will become anemic.  This secondary form can be caused by several conditions, such as:  cancer, infection, blood parasites, drug reactions, snake bites, chemicals/toxins, bee stings, or allergic reactions. 

Symptoms of either form of IMHA may include:  pale gums, lethargy, shallow or rapid breathing, rapid pulse, lack of appetite, weight loss, black/tarry stools, or eating dirt.  Symptoms may vary depending on the underlying cause, and in mild or early stages of the disease, no signs may present at all. 

If any of the above-mentioned symptoms are noticed, you should make an appointment with your veterinarian as soon as possible.  Your vet may recommend a series of tests to diagnose your pet’s condition, as well as rule out others.  Tests may include a complete blood count to identify anemia, followed by a reticulocyte count to identify if the body is making new red blood cells.  Other tests to find or rule out underlying conditions may include:  a blood film, blood chemistry, electrolyte tests, urine tests, fecal analysis, and/or radiographs or ultrasounds.

Once your veterinarian has a confirmed diagnosis of IMHA and any underlying conditions that may be present, a plan for treatment may be formed.  Treatment of IMHA will depend on the severity of the disease.  In serious cases, an animal may need intensive care, but in milder cases they may be treated as an outpatient.  Treatment will often include drugs and close monitoring of the animal’s vital signs and lab values, meaning more blood tests may be performed as treatment goes on. 

IMHA should be taken very seriously and treated as soon as possible.  Contact your veterinarian today if you’re concerned about anemia in your pet!