My injured/sick horse?

You don't say whether the injured leg was a front or rear leg. uming it was a front leg, and that the skin infection you are referring to might have been cellulitis, which is the spread of infection within the skin and subcutaneous tissues, the swelling in his shoulder may be related and could be an abscess. Was the entire leg swollen? I'm not sure what you mean by the same skin irritation that he had on his leg. I thought the leg issue was an injury? Was there also a skin condition such as scratches? It would be helpful if you add to your question with more details including which leg was affected and what the injury was and the nature of the skin irritation.