dead skin on wound

My dog has a skin Lesion due to a cage injury. He tried to get out the cage under the metal bars. He has puss areas to which i have been cleaning with Prioxide and he is currently on antibodics witch the vet proscribed. How soon do I need to get the dead tissues removed??

I understand, but the first time I took him to the vet his skin was still attached so they told me to give him his anticboics twice a day and clean him. A week went by and his fur begin to shed greatly. Ranging from his shoulders to his tail area. At first his lower back was trying to form a scab but soon went back to displaying a white meat area. Towards his shoulders ( a square area) I am actullay able to see his skin lift up when he shakes off once again exposing his white meat area. I do see puss coming out the wounds witch i do clean on a daily bases. He is sensitive to the touch ,but will allow me to clean it. I took him to a second vet to get a second opinion to which they said that he had dead skin that needed to be removed asap. Im a college student doctor and my dog is the love of my life besides my books and studying. They told me that he needed surgery that would cost me about $600.00 dollars. For me thats alot of money but I am willing to do whatever it takes to make my dog well. I just need to know if thats my only option? and if so if rex have being dealing with this for about two weeks if it is possible that he can go another two weeks until i can come up with the money? Or should I go and get a third oppinion doctor? I tried to apply for carecredit but because Im only 20 years old I dont have an extended credit amount for the loan.