What Is IMHA and How Did My Cat Get It?


Immune-mediated hemolytic anemia is a condition where the cat’s immune system turns against itself and attacks the patient’s own red blood cells. The immune system’s antibodies (blood proteins that are designed to counteract substances the body recognizes as alien, such as viruses and bacteria) target red blood cells for destruction. When too many red blood cells are destroyed, the patient becomes anemic.

Symptoms of IMHA

Your cat may be lethargic and weak. She may have lost interest in food. Her gums may be pale, or jaundiced (yellow tinged). You may also notice a yellow tinge to the whites of her eyes. Urine may be dark orange or even brown. She may have a fever. You may notice an increased heart and respiratory rate. In advanced cases, your cat may collapse.

Diagnosis of IMHA

Your cat’s veterinarian will conduct a thorough physical exam and run a number of blood tests. These tests will include a complete blood chemistry and blood count, a PCV (packed cell volume) test to measure the percentage of blood which is occupied by red blood cells, a Coombs test to detect the presence of antibodies, and a blood smear (red blood cells clumped together will be an indicator of IMHA.) Other blood tests may be indicated to look for indications of infection or parasites. Your vet may also take x-rays to look for tumors and to rule out other underlying conditions.

Treatment of IMHA

Treatment and your cat’s prognosis will depend on the underlying cause of IMHA. When possible, the underlying disease process needs to be treated. Other treatment may include supportive care, such as intravenous fluids.

Corticosteroids are an important part of treatment, as they suppress the immune system. Patients are likely to be on high doses of corticosteroids for weeks or months before the dose is tapered down. Your cat will need to be monitored with regular blood tests during treatment. Many IMHA patients will need to always be on a low dose to prevent recurrence.

If the red blood cells have dropped to critically low levels, your cat will need a blood transfusion. Transfusions with artificial blood may be a better choice than real blood for IMHA patients, since it won’t further stimulate the patient’s already compromised immune system. The downside of artificial blood is that it won’t last as long in the body, but it can buy enough time until a compatible blood donor is found.

What Causes IMHA?

IMHA in cats is most commonly caused by either the feline leukemia virus or an infection with a red blood cell parasite called hemobartonella felis. IMHA can also be caused by drug side effects, toxins, or cancer.

IMHA is a serious condition with a high mortality rate. Patients are often unstable, and treatment can be lengthy and costly. Cats who are susceptible to IMH may have recurrences months of years into the future.

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This article was previously published on Answers.com and is republished with permission.

6 Comments on What Is IMHA and How Did My Cat Get It?

  1. Leah L
    February 1, 2018 at 2:34 pm (8 months ago)

    My 7 year old male cat has primary IMHA. He was diagnosed in January, 2016, and this has been a roller coaster ride for all of us. He has had numerous recurrances and each time it gets harder to push into remission. He currently has it full blown, his HCT/PCV is only 9.2 and the vet doesn’t understand how he’s still alive. He is having Dexamethasone shots and we pray they will work again. This is a horrible, unpredictable disease and I wonder often if we’re doing the right thing with the shots, vet visits, labs, etc. His quality of life isn’t good most of the time. It is heartbreaking to watch and deal with.

  2. lucy
    November 7, 2017 at 9:44 pm (11 months ago)

    very scarry. i never heard of this problem before.
    thank you .

  3. Janine
    November 6, 2017 at 9:16 am (11 months ago)

    I have never heard of this condition. Thanks for the information!

  4. Sue Brandes
    November 6, 2017 at 8:23 am (11 months ago)

    Thank you for the post. Never heard of this before.

  5. Kitty Cat Chronicles
    July 22, 2014 at 11:23 pm (4 years ago)

    I had never heard of this before. Thank you for sharing. Also, great reminder about onions. I knew they were really bad for kitties, but never really knew why.

  6. Sue Brandes
    July 22, 2014 at 10:26 am (4 years ago)

    Thank you for the informative post. I never heard of this before.


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