This study was performed to evaluate the effects of nandrolone decanoate (ND) on immobilized skeletal muscle atrophy and on bone healing in dogs.

Twenty adult dogs (3.3kg~5.5kg and 2~4 years) were divided into three groups according to the amount of ND (Deca-Durabolin® 50mg/ml, Hanhwa Co., Korea) administered; no treatment (group A), 1.5mg/kg ND (group B) and 7.5mg/kg ND (group C). The radius was excised 1mm in length with oscillating bone saw just below the pronator teres muscle and fixed with a plate. ND was injected intramuscularly once a week for 8 weeks from the day of surgery. Robert John's bandage was applied to the dogs. Body weight was measured using electric balance and muscle mass with tapeline at proximal one fourth of the antebrachium immediately after surgery, 2, 4 and 8 weeks. Bone healing was evaluated by radiography and histological examination.

The change rates of muscle mass at 8 weeks in the groups A, B and C were -2.75±0.16%, 1.68±0.11% and 1.74±0.48%, compared to the initial muscle mass, respectively. The increments of muscle mass at 4 and 8 weeks were significantly different between control and the treated groups (p<0.05). There was no significant difference between low and high dose treated groups. More fibrous and connective tissue layer between the fractured gaps were appeared in the treated groups, particularly in group C than the control at 4 weeks. However, there was no difference in evaluation of bone healing among all groups at 8 weeks.

The present study suggested that ND was effective for immobilized disuse muscle atrophy in dogs.