It's possible that in the next week I will be getting an approx. 1 year old male GSD from a rescue centre. The dog is basically sound apart from his showing ribs and possibly weak in the back legs. So any suggestions on how to build up his muscles? He seems to be a very good natured dog trying to lick people's hands through the wire mesh of his kennel. He is very attentive and notes what is going on around him.