I hadn't really heard of the muscle wasting before either but it was quite noticable with Tiger and a few of the vets said it was due to the prednisilone. Tiger was on a much higher dose than my cat Jimmy because at the time, when it hadn't yet been determined what was causing Tiger's breathing difficulties, the prednisilone was the only thing that was making it possible for him to get enough air. I had him on 10mg a day which is an insanely high dose for a cat and could have been life threatening in itself if continued indefinitely but at that point he was on death's doorstep and I was just buying time and it was all under the vet's supervision. All of the vets were wary of giving him so much but basically told me to go ahead with it because they didn't know what else to do for him. Thankfully the last vet found the tumour and we were then able to wean him off the pred. If I do start giving it to him again, I'm sure the dosage prescribed will be quite a bit less.