A retrospective evaluation of the steroid sparing effects of oral mycophenolate mofetil (MMF) as an adjunct immunosuppressant for the treatment of canine pemphigus foliaceus

Background Oral mycophenolate mofetil (MMF) is currently considered a low-risk steroid-sparing therapeutic option the management of canine pemphigus foliaceus (PF). Objectives This retrospective study evaluates the therapeutic outcomes of dogs with PF treated with the combination of oral MMF and GC. Clinical outcomes and side effects are reported. Animals Eleven dogs diagnosed with PF. Methods and materials Retrospective review of medical records from dogs presented with PF to the dermatology service of a veterinary teaching hospital 2015-2020. Results Eleven dogs were identified which had received concurrent GCs and MMF. The MMF dose range was 19.8-45 mg/kg/day. Only two dogs (2/11) treated with a mean MMF dosage of 39 mg/kg/day along with oral prednisone or dexamethasone achieved complete remission (CR). Partial remission (PR) was achieved in 4/11 dogs who received either prednisone, prednisolone or dexamethasone along with MMF (mean dosage 26 mg/kg/day). Four dogs (4/11) showed poor response to MMF given at 28.5 mg/kg/day along with prednisone or dexamethasone. In one dog (1/11) MMF was discontinued due to severe GI upset; transient vomiting and diarrhea was observed in 4/11 dogs. The median duration of MMF therapy in conjunction with GC for all groups was 70.5 days. Tapering of oral GCs while continuing MMF administration at the same dosage and frequency led to recurrence of lesions in all PF patients. Conclusion Oral MMF combined with GC achieved CR in 2 out of 11 PF dogs included in this study. Further research of MMF efficacy in PF may need to be performed.