4 weeks? Wow, he's gonna go nuts! Cut down his food, for sure. Will you be able to hand walk him regularly -- like several times a day? I guess they really want to make sure he doesn't open his wound. But even so -- 4 weeks?
There are bandages that can be had now to support such types of surgeries. I wonder if you can buy one, or perhaps you can borrow one. But if you do handle a used one, be sure to sterilize it well to prevent spread of disease, etc.
Glad to head that everything went as expected. How is he doing now?