The treatment of autoimmune hemolytic anemia in dogs

TREATMENT



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The following therapies are used in the treatment of autoimmune hemolytic anemia. However, it should be noted that each dog diagnosed with this disease will tolerate each treatment in a different manner. Because of that fact, be certain to discuss all treatment options with your veterinarian, before embarking on any treatment program for your dog.

DRUG THERAPY

The cornerstone of treatment for autoimmune hemolytic anemia (AIHA) is the drug prednisone. Prednisone is a corticosteroid drug that suppresses the immune system. Very high doses of this immunosuppressive drug are given initially in an effort to stop the destruction of red blood cells and thus induce a remission. It can take about 5-7 days for prednisone to start to work. The minimum dosage of prednisone given at the onset of AIHA is 1 mg per pound of the dog's weight per day divided into two dosages. Some clinicians will prescribe an even higher dosage for dogs with a very low PCV. The dosage of prednisone should be tapered off very slowly over many months. The aim is to get the dog to the lowest maintenance dosage possible or off the drug completely. Some adverse side effects associated with prednisone usage are; increased thirst and urination, increased appetite resulting in weight gain, increased panting, muscle weakness and increased susceptibly to infections due to the suppressed immune system. Long term prednisone use may result in liver damage. Dexamethasone, a corticosteroid drug, which is five to seven times more potent then prednisone is also used in the treatment of AIHA. Some veterinarians advocate giving corticosteroids at least one week to work before adding other drugs to the treatment regimen while other veterinarians prefer to add cytotoxic drugs at presentation.
If steroids alone are insufficient, more potent immunosuppressive drugs such as azathioprine, sold under the brand name Imuran may be added. Imuran is a "second-line" or "slow acting drug." Clinical response may require up to 6 weeks. The principal adverse effect associated with Imuran is bone marrow suppression. Acute pancreatitis and hepatotoxicity have also been associated with Imuran. Because Imuran depresses the immune system, animals may be susceptible to infections or neoplastic illnesses (long term use).
Another potent drug used in the treatment of autoimmune hemolytic anemia is cyclophosphamide sold under the brand name Cytoxan. Cytoxan may be used in cases with severe hemolysis and agglutination. The usual manner in which Cytoxan is given is daily for 4 consecutive days per week, stop for 3 days and then repeat. Because of the potential for development of serious adverse effects, Cytoxan should only be used in patients who can be adequately and regularly monitored. Primary adverse effects in animals associated with Cytoxan are bone marrow suppression, gastroenterocolotis (nausea, vomiting, diarrhea) alopecia (hair loss) and hemorrhagic cystitis.
Cyclosporine has revolutionized organ transplantation in humans since its introduction in 1983. It has also been used in autoimmune diseases in humans and now is starting to be used in veterinary medicine for the treatment of autoimmune diseases, such as autoimmune hemolytic anemia. It is very important to measure blood cyclosporine levels when the drug is being used.The therapeutic range for cyclosporine is from 300-500 ng/ml (nanogram/milliliter). One reason that frequent blood testing is necessary with cyclosporine is that there can be a great deal of variability in its absorption. One dog may absorb a larger percentage of the prescribed dosage then another. Cyclosporine concentration blood tests called trough tests are not able to be done "in-house" at veterinary clinics nor do most outside labs run cyclosporine levels. Trough tests are usually sent to veterinary teaching hospitals, to be run. The blood for the trough test must be drawn at the exact time a dosage of cyclosporine is scheduled to be given. This allows the lowest amount of cyclosporine in the body to be measured on the trough test. Since cyclosporine saturates the tissue, the dosage may need to be adjusted from time to time, another reason trough testing is so important. Because cyclosporine interacts with a variety of other drugs it should be used with caution with other medications. To get the full benefit from cyclosporine the dog must be on a very strict feeding and dosing schedule. The diet must be consistent without any deviations in amount, type of food or feeding time. Because cyclosporine has a half life of only 19 hours it must be given every 12 hours. Cyclosporine is sold under many brand names including Neoral, Gengraf and Atopica.
Danazol is a drug primarily used as an adjunctive therapy with corticosteroids (such as prednisone) in the treatment of canine autoimmune hemolytic anemia. There is apparently synergism when Danazol is combined with corticosteroids for this purpose. Once remission is attained, some dogs may have their Danazol dosage reduced or other medications may be eliminated and the disease may be controlled with Danazol alone.

BLOOD TRANSFUSIONS

Blood transfusions can be used in dogs with autoimmune hemolytic anemia if necessary. However, adding foreign protein can actually intensify the crisis state, increase the amount of bilirubin and other breakdown products the liver must process and suppress the bone marrow’s natural response to anemia. If blood transfusions are given, they should be done only in a life threatening situation and then done with great caution. The blood must be typed and crossed matched to avoid further sensitization and exacerbation of the problem.
In January, 1998 the FDA approved the first artificial blood for use in canines called Oxyglobin. The primary advantage of Oxyglobin over whole blood is that it can deliver oxygen to the cells several times faster then real blood and thus provide an "oxygen bridge" to the cells. This may give the body the additional time it needs for the drugs to begin to work. Oxyglobin has a shelf life of up to two years and does not need to be typed and cross matched.

HUMAN INTRAVENOUS IMMUNOGLOBULIN

Human Intravenous Immunoglobulin (IVGG) is a blood product administered intravenously. It contains the pooled IgG immunoglobulins extracted from the plasma of many human blood donors. IVGG is used in humans for many conditions and has been used in some cases of canine AIHA/IMHA when the patient does not respond to other therapies.
To learn more about IVGG use for the treatment of canine AIHA/IMHA please click on the following links:
Use of human intravenous immunoglobulin in dogs with primary immune mediated hemolytic anemia
Intravenous administration of human immune globulin in dogs with immune-meditated hemolytic anemia
Effects of human intravenous immunoglobulin on canine monocytes and lymphocytes
Intravenous human immunoglobulin for the treatment of immune-mediated hemolytic anemia in 13 dogs

SPLENECTOMY

Splenectomy, the surgical removal of the spleen, is occasionally recommended for cases of autoimmune hemolytic anemia that have been nonresponsive to other forms of treatment. This surgery benefits the dog in two ways; less antibodies are made against the red blood cells and the primary organ responsible for the destruction of the red blood cells is removed.

SECOND OPINIONS/CONSULTATIONS

If you feel that your veterinarian is not up to-date on all the treatments available for AIHA, please ask him/her to consult with a veterinary teaching hospital or refer you to a veterinary internal medicine specialist.

Editor's Notes

To learn how you can help fund humane canine AIHA/IMHA health studies at Morris Animal Foundation Click Here

Links to other sites

Prednisone information page
Corticosteroids/Prednisone information page
Dexamethasone information page
Azathioprine/Imuran information page
Cyclophosphamide/Cytoxan information page
Cyclosporine information page
IMHA treatment's first goal to improve oxygen delivery to cells
Management of Hemolytic Anemias
Evaluation of prognostic factors, survival rates, and treatment protocols for IMHA in dogs
List of Colleges of Veterinary Medicine
Search for an ACVIM Diplomate in the Specialty of Internal Medicine
This page was last updated on February 11, 2014.
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