Low Platelet count

My 10 year old female greyhound has been on prednisone for a low platelet count for about 9 months.  She appears stable while on the meds.  We've tried weaning her (5-10mg every other day), but end up increasing the dose (20mg/day).  What is the chance she'll have to remain on the prednisone for the remainder of her life, and can being on the medication actually shorten her life span?  She's in otherwise good health and pampered beyond belief!  Thanks in advance for your response!  

[Aleda M Cheng, D.V.M., C.V.A]

Does your dog have immune-mediated thrombocytopenia?  Does your veterinarian know what the cause of the anemia is?  Is it secondary to drug therapy, infections (such as Anaplasmosis), vaccine reaction, or other immune diseases such as immune-mediated hemolytic anemia, or a bone marrow problem?  Does your dog have Evan