A retrospective study of adverse effects of mycophenolate mofetil administration to dogs with immune-mediated disease

Background Information regarding adverse events (AEs) of mycophenolate mofetil (MMF) is limited. Objectives To evaluate the types and frequency of potential AEs of MMF in dogs with immune-mediated disease. Animals One hundred thirty-one dogs treated with MMF for management of suspected immune-mediated disease. Methods Retrospective study. Medical records were reviewed to find and group suspect AEs in gastrointestinal (GI), hematologic, and other categories. Age, dosage, body weight, and sex were analyzed between dogs with and without AEs by using the Mann-Whitney U-test and chi-squared test. Results The median starting dosage of MMF was 17.5 mg/kg/day (interquartile range [IQR] = 15.1-20.6 mg/kg/day) and the median treatment duration was 56 days (IQR = 14-236 days). Mycophenolate mofetil was prescribed for immune-mediated hemolytic anemia (n = 31), immune-mediated thrombocytopenia (n = 31), pemphigus foliaceus (n = 15), immune-mediated polyarthritis (n = 12), and others (n = 42). Overall, potential AEs of MMF were observed in 34 of 131 dogs (GI 24.4% [31/127], neutropenia 4% [3/76], anemia 4% [1/25], thrombocytopenia 4.0% [1/25], and dermatologic 1.5% [2/131]). There were no significant differences among dogs with (n = 37) or without potential AEs (n = 94) in regards to sex, age, body weight, or dosage of MMF (P = .06, .13, .24, and .26, respectively). Conclusions and Clinical Importance In the dogs administered MMF, GI AEs were most common. Since potential hematologic and dermatologic AEs developed in a few dogs, clinicians should be aware of these when prescribing MMF to dogs with immune-mediated disease.