What is the current recommended treatment protocol for MUO in dogs including immunosuppressive regimens?

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Corticosteroids are the cornerstone of MUO treatment, used either as monotherapy or in combination with a second immunosuppressive agent. No gold standard protocol exists, and treatment choice is currently guided by clinician and owner preference. 5 Prednisolone monotherapy produces median survival times of 28 to 602 days, while combination therapy with corticosteroids plus a second immunosuppressive agent is associated with improved survival times ranging from 250 to 1,834 days. 7 One-third of dogs deteriorate within the first 72 hours after treatment initiation regardless of protocol. 6 Without treatment, MUO is considered fatal. 7 Dexamethasone is an acceptable alternative to prednisolone for initial induction, with 0.5 mg/kg/day IV and 2.0 mg/kg/day IV producing equivalent short-term neurological outcomes over a four-day hospitalization period; neither dose regimen has demonstrated superiority in short-term efficacy or gastrointestinal safety. 2 Second-line immunosuppressive agents used in combination with corticosteroids include cytosine arabinoside (CA), cyclosporine, lomustine, procarbazine, leflunomide, mycophenolate mofetil, and azathioprine. 157 No prospective head-to-head comparisons between these agents exist. 7 Cyclosporine added to prednisolone is associated with a lower relapse rate compared with prednisolone alone in dogs with spinal MUO (meningomyelitis). For dogs treated with corticosteroids alone that experience clinical relapse, addition of a second immunosuppressive agent is recommended. 1 CA administered as a continuous rate infusion (CRI) at the time of diagnosis improved 3-month survival times compared with subcutaneous CA injection; however, adding CA to a cyclosporine-and-prednisone protocol at diagnosis did not improve outcomes. 3 Whole-brain radiation therapy (5 × 4 Gy) combined with prednisolone is a second-line option, particularly for cases requiring rapid symptom relief or with a relapsing history. Neurological status improved in all