Castration of a male dog is a surgical procedure that needs to be done in a sterile environment in order to prevent infection from occurring. The dog's coat is shaved over the surgical area and then the skin is scrubbed clean in a methodical way to make sure all dirt and debris is removed. Prior to the start of the operation, the skin is then further treated with a surgical skin preparation solution.
Remember this the next time you go for a haircut. 
