clean

jaundice Immune-Mediated Hemolytic Anemia

TREATMENT AND MONITORING DURING THE CRISIS

The patient with IMHA is often unstable. If the hematocrit has dropped to a dangerously low level then blood transfusion is needed. It is not unusual for a severely affected patient to require many transfusions. General supportive care is needed to maintain the patient’s fluid balance and nutritional needs. Most importantly, the hemolysis must be stopped by suppressing the immune system’s rampant red blood cell destruction. We will review these aspects of therapy.

TRANSFUSION

There are several products that may be helpful in treating the IMHA case. If the patient is in a crisis and needs immediate therapy, artificial blood may be a good choice. Artificial blood (Oxyglobin®) is made from hemoglobin harvested from cow’s blood. Because the patient does not receive actual red blood cells, the artificial blood does not further stimulate the immune system. Artificial blood does not require refrigeration and is likely sitting on the shelf ready to use at your veterinarian’s office. The disadvantage of artificial blood is that it does not last in the body like a well-matched blood transfusion does. The body begins removing artificial blood immediately so that the entire transfusion is probably gone in 48 hours or so. In IMHA, this may buy some time but since IMHA tends to have a long treatment course, it is likely that the patient will be back where they started from at that point. If a compatible donor is not readily available, sometimes an artificial blood transfusion buys enough time to find a compatible donor.

Well-matched whole blood or packed red cells (a unit of whole blood with the plasma mostly removed leaving only a concentrated solution of red blood cells) may last longer. Compatible blood can last a good 3-4 weeks in the recipient’s body. The problem, of course, with IMHA is that even the patient’s own red blood cells are being destroyed so what chance do donated cells have? Cross matching of red cells is ideal but still may not lead to a good match given the hyperactivity of the patient’s immune response. For this reason, it is not unusual for several transfusions to become necessarily in the treatment of this condition.

IMMUNE SUPPRESSION

Corticosteroid hormones in very high doses are the cornerstone of immune suppression. Prednisone and dexamethasone are the most popular medications selected. These hormones are directly toxic to lymphocytes, the cells that produce antibodies. If the patient’s red blood cells are not coated with antibodies, they will not have been targeted for removal so stopping antibody production is a very important part of therapy. These hormones also suppress the activity of the Reticuloendothelial cells that are responsible for the removal of antibody coated red cells.

Corticosteroids may very well be the only immune suppressive medications the patient needs. The problem is that if they are withdrawn too soon the hemolysis will begin all over again. The patient is likely to be on high doses of corticosteroids for weeks or months before the dose is tapered down and there will be regular monitoring blood tests. Expect your pet to require steroid therapy for some 4 months; many must always be on a low dose to prevent recurrence.

Corticosteroids in high doses produce excessive thirst, re-distribution of body fat, thin skin, panting, predisposition for urinary tract infection and other signs that constitute Cushing’s Syndrome. This is an unfortunate consequence of long term steroid use but in the case of IMHA, there is no way around it. It is important to remember that the undesirable steroid effects will diminish as the dosage diminishes.

MORE IMMUNE SUPPRESSION

If no response at all is seen with corticosteroids, supplementation with stronger immune suppressive agents is necessary. The two most common medications used in this case are: azathioprine and cyclophosphamide. These are very serious drugs reserved for serious diseases. Please follow the links above to read more about specific side effects concerns etc.

Cyclosporine is an immune-modulator, made popular in organ transplantation technology. It has the advantage over the two above medications of not being suppressive to the bone marrow cells. It has been a promising adjunctive therapy in IMHA but has two major problems: first, it is extremely expensive and second, blood level monitoring is necessary to ensure that the dosage is appropriate. This adds dramatically to the expense of treatment but ultimately may provide the results not possible with other drugs.

Leflunomide is a new immuno-modulator that is meant for patient with immune mediated diseases when corticosteroids either do not work or cannot be used. It is expensive (approx $600 per month) but we may be hearing more about it in the future.

Human Gamma Globulin transfusion is a treatment that is reserved for patients for whom more traditional methods of immune suppression have been ineffective. The gamma globulin portion of blood proteins includes circulating antibodies. These antibodies bind the reticuolo-endothelial cell receptors that would normally bind antibody coated red blood cells. This prevents the antibody coated red blood cells from being removed from the circulation. Human Gamma Globulin therapy seems to improve short term survival in a crisis but, unfortunately, availability of the product is limited and it is very expensive.

Source: Regarding one's pet (dog or cat) ... but also an issue for humans that can be overlooked when from 2-butoxyethanol overexposure http://www.marvistavet.com/html/body_imha.html

IMHA is a very serious disease associated with a high mortality rate. Sadly, many dogs have succumbed. Several pet owners have used these sad events to create outstanding informational web sites on IMHA in tribute and to help others. We have found these site especially noteworthy and recommend them highly: