Effects of prednisone in canine muscular dystrophy.

Glucocorticoid use may provide short-term functional im- provement in boys with Duchenne muscular dystrophy (DMD). We report functional and histopathologic changes following a 4-month course of daily oral prednisone in a canine model of DMD, termed golden retriever muscular dystrophy (GRMD). Muscle extension forces in GRMD dogs treated daily with 1 and 2 mg/kg prednisone measured 2.349 0.92 and 3.486 0.67 N/kg, respectively, compared to 1.927 0.63 N/kg in untreated GRMD controls (p 0.05 for 2mg/kg group); GRMD muscle flexion forces mea- sured 0.435 0.13 and 0.303 0.08 N/kg, respectively, compared to 0.527 0.01 N/kg in untreated GRMD controls (p 0.05 for both groups). Although cranial sartorius hypertrophy and tibiotarsal joint angles also tended to improve, myofiber calcification increased and fetal myosin expres- sion decreased following prednisone. Thus, functional data indicate benefit but histopathologic changes following prednisone treatment in GRMD sug- gest possible deleterious consequences. Muscle Nerve 30: 767-773, 2004