Mycophenolate Mofetil for IMHA

Treatment for idiopathic immunemediated hemolytic anemia (IMHA) is aimed at immunosuppression and supportive care, including blood product transfusions. This study examined 5 dogs with idiopathic IMHA treated with the immunosuppressive drug mycophenolate mofetil (MMF) in addition to prednisone, low-dose aspirin, and supportive therapy. All dogs survived beyond 2 weeks of diagnosis; 3 were still alive >1 year after diagnosis. One was euthanized on day 20 because of uncontrollable IMHA, unresponsive even after the addition of cyclosporine on day 7. A second dog was euthanized on day 115 because of uncontrollable diarrhea thought to be an adverse effect of MMF. On necropsy, both euthanized dogs were found to have ulcerative enterocolitis with crypt necrosis. All dogs experienced GI toxicity of varying degrees, thought to be a result of MMF administration. Two patients had severe enough adverse effects to warrant MMF discontinuation. Median time to resolution of spherocytosis and anemia was 13 days and 44 days, respectively, but the lack of a control group makes this data difficult to interpret, as corticosteroids alone could have yielded similar results. Therefore, it is imperative that future controlled studies be conducted comparing these various treatment choices, and at a lower dose of MMF than used in this study.

Commentary

MMF, in addition to corticosteroids, has become my go-to immunosuppressant for dogs. MMF coadministered with corticosteroids allows for a lower corticosteroid dose and a more rapid corticosteroid taper. Long-term use of prednisone has more adverse effects (eg, weight gain, muscle weakness, recurrent infections, hair loss) than does MMF. My plan for many patients is to taper corticosteroids completely and control the disease with MMF alone. Adverse effects of MMF are not common at the dose I use (10 mg/kg q12h). In this study, a higher dose was used (10–15 mg/kg PO q8h), which may explain the frequency of diarrhea. These dogs were also receiving prednisone, aspirin, and doxycycline and their impact cannot be excluded. Most unusually, cases were responsive to the administration of metronidazole which would not have been expected if MMF was the culprit.—Michael Stone, DVM, DACVIM

Source

Treatment of idiopathic immune-mediated hemolytic anemia with mycophenolate mofetil in five dogs. West LD, Hart JR. JVECC 24:226-231, 2014.