Immune-mediated hemolytic anemia Veterinary Specialists of

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					Immune-mediated hemolytic anemia
Veterinary Specialists of Rochester

Immune-mediated hemolytic anemia is an immune-mediated disease in which the body sees its
own red blood cells as “foreign”. Therefore, the body attacks and destroys the red blood cells.
Subsequently, the dog’s red blood cell count drops. When their blood cell count becomes too
low, animals start to show signs of anemia (low red blood cell count). Symptoms include
decreased energy, weakness, collapse, and pale gums. This disease, and its symptoms, can come
on slowly, but more often, it comes on very quickly.


IMHA can have a variety of initiating causes. While anything that stimulates the immune system
can trigger IMHA, the most common causes include:

       Medications:
            o Antibiotics:
                     Cephalosporins including Cephalexin and Simplicef
                     Penicillins including amoxicillin, ampicillin, and Clavamox
                     Sulfa drugs including trimethoprim-sulfa
            o Vaccinations
       Infections:
            o Tick-borne diseases
            o Heartworm infection
       Cancer
       Inflammatory (non-infectious) diseases
            o Pancreatitis
       Idiopathic
            o This means that no underlying cause of the disease is found. In the majority of
                cases of IMHA, no underlying cause is determined.

To look for potential underlying causes of IMHA, numerous tests are performed. We obtain a
thorough history see if any medications or vaccinations have been given recently. Heartworm
and tick-borne diseases are tested for using blood tests. An abdominal ultrasound is performed
to look for signs of infection, inflammation, or cancer within the abdomen. Radiographs (x-rays)
of the chest help us to rule out disease there.

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Immune-mediated hemolytic anemia
Veterinary Specialists of Rochester

If an underlying cause of the disease is found, it is treated appropriately. For idiopathic IMHA,
immunosuppressive medications are used. There are a variety of drugs that can be used to
suppress the immune system and often a multi-modal approach.

       Glucocorticoids including prednisone, prednisolone, and dexamethasone: These
        medications are the most common type used for immune-mediated diseases. They
        suppress the immune system in a variety of ways and are the first line medication for
        immune-mediated disease. The most common side effects include increased urination
        TIMES), and increased hunger (you do not need to feed more food). Some dogs will pant
        with steroids. Some large breed dogs will show hind end weakness with steroids.
        Steroids can cause gastrointestinal ulceration. Therefore, you should notify your
        veterinarian if you notice any vomiting, diarrhea, decreased appetite, blood in the stool,
        or dark tar-like or coffee-ground like stool. Steroids can increase the risk of forming
        blood clots (see thromboembolism below). A life-threatening crisis can develop if you
        stop this medication too quickly. Therefore, you should only change the dose of this
        mediation under advisement of a veterinarian. While on the prednisone, it is important
        that you do not give any aspirin or non-steroidal products (Rimadyl, Deramaxx,
        Metacam, etc) as giving these two types of medications together will result in GI ulcers.
       Azathioprine: This immunosuppressive medication is often used as second line therapy.
        Side effects include: liver disease, pancreatitis, and bone marrow suppression. Please
        notify a veterinarian if your pet has any of the following symptoms while on this
        mediation: vomiting, diarrhea, yellow color of the skin/whites of the eyes/gums,
        abdominal pain, weakness, or collapse. Wash your hands after giving this medication.
       Cyclosporine: This immunosuppressive medication can be used as a second or third-line
        treatment, but is more expensive and is more likely to cause GI upset.
       Cellcept/mycophenolate: This immunosuppressive medication can be used as a second or
        third-line treatment, but is more expensive.
       Overall, your pet will likely be on these medications for at least 4-6 months. We will
        slowly taper the medications, checking the blood work prior to each decrease. If your pet
        has a relapse during the taper period, he or she may need to stay on life-long therapy.

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Immune-mediated hemolytic anemia
Veterinary Specialists of Rochester

       Thromboembolism: Patients with IMHA are at increased risk of developing blood clots.
        Therefore, we place patients on low doses of aspirin. It is very important that you do not
        change the dose of this medication, as higher doses can cause ulcers. If a clot forms, it
        can go anywhere in the body. The most common location is that it goes to the lungs so
        please monitor for increased respiratory rate and effort, collapse, and weakness. Blood
        clots can also go to the brain, kidneys, heart, GI tract or legs.
       Infections: IMHA is treated with immunosuppressive medications. Therefore, your pet
        will be at increased risk of infections. The most common area of infections is the urinary
        system, but they can also get infections of the skin or respiratory systems. Please monitor
        for the following symptoms and have your pet evaluated by a veterinarian if you see any
        of these symptoms: straining to urinate, painful urination, bloody urine, red skin, itchy
        skin, increased respiratory rate or effort, or cough. Raw food diets pose a risk of causing
        infections and, therefore, should not be given to pets with immune-mediated anemia.
       Relapse: your pet is at risk of a relapse anytime in the future. He or she may start
        attacking the red blood cells again or the body may start attacking other areas such as the
        platelets (immune-mediated thrombocytopenia) or the joints (polyarthritis). This may
        happens while your pet is still on the medication or it may happen years in the future.
        Therefore, if you think your pet is sick in any way, take him or her to a veterinarian
        sooner rather than later. The body is more prone to attacking itself whenever the immune
        system is stimulated. Therefore, pets with IMHA should not receive any further
        vaccinations as this could spur another attack. Usually a letter can be written to get
        your pet out of having to be vaccinated for rabies. Certain medications are more at risk of
        causing a relapse as well including: cephalosporins (Cephalexin, Simplicef, cefazolin),
        penicillins, and sulfa drugs. These medications should be avoided.

IMHA patients need very close monitoring. We will be rechecking your pet’s red blood cell
count. At first, the red blood cell counts will be monitored every few days. Then we will cut
back to monitoring every 2-3 weeks. If the values are holding, we will then decrease the dose of
one of the medications by about 25%. We will decide the exact amount of the decrease
depending on how your pet is doing at home and on blood work. Since your pet will be more
susceptible to infections, we will also be checking urinalysis and urine cultures every few
months. We will also be checking full chemistries periodically. Once your pet is completely off
of all medications, we recommend rechecking basic blood work (complete blood count and
serum biochemistry) as well as urinalysis every 4-6 months long term.

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