Clean it. Soak it with Epsom salts. Clean it every day and try to get rid of any pus or dead tissue. Hose it with dilute betadine. You are getting a lot of good advice on basic wound managment that your vet didn't give you.
You might even try a good wash with dawn soap and a hose, first, just to get rid of loose stuff and goo that needs to come off. The salt soak, betadine rinse, antibiotic ointment and then wrap. Lots of oral or injectable antibiotics.
Always remember half the vets graduated in the lower half of their class. Maybe your vet didn't get a good grade in wound managment.
I really hope it heals and don't really see why it shouldn't unless he has MRSA or something. Be proactive and kick germ butt!