My gelding's diagnosis is far from complete, Nrharainer you are correct, this is a terrible anatomical spot for doing xrays. My vet opted for an utltrasound. It showed no blood clots or fluids so a hematoma was ruled out. The swelling is all muscle mass. The ultrasound is very difficult for determining exactly what is going on however he said its either a slight chip in his scapula and/or muscle/tendon pulling or tearing from the scapula bone.
Again, these are only speculations as we were unable to do an x-ray. The mystery in this situation lies in the fact that this type of injury had to be incurred from hard force or blunt trauma. The problem is he was not exposed to anything which would make succeptible to this kind of injury the day or night preceeding the swelling. It was a non-riding day and he was by himself in his stall without other horses to injure him.
Something must of happened in the night, that is the only feasible explanation, but again, he showed no marks on his body if he did fall, or perhaps got cast under the pipe corral. Now...all I can think is I really wish I had a night vision camera to monitor what goes on when I'm not around!!
He is sound for the most part so he will have 2 weeks off and then light walking for the following 2 weeks, I hope by then the mysterious mass dissapates on its own.
Thank you all for your interest and I wish the best of health for your equine partners! ** Please let me know if you have any additional advice for his re-hab!