First things first - thank heavens it's benign! That's one big hurdle down.

You might ask the vet if he will consider putting in stitches or staples on the section that opened up. We had that with Ziggy and the staples really helped things - he had a revision to his first incision and it was Y shaped, and opened up at the joining of the legs of the incision. We had the infection issue too - is he still on an antibiotic for that?

The food thing is tougher. He may not be drinking because of the subcutaneous fluids? That would be my guess. If this is his first day off the gabapentin, maybe his appetite will start to improve. My thing was always offering the stinkiest food possible or different things. Bits of unseasoned scrambled eggs, treats, cheese, whatever would get him interested. 

It's worth remembering that those deep wounds heal from the bottom up in some cases. Ziggy's was filling in slowly with fibrin when we finally took him back because it was freaking us out, but it did heal up! While we were waiting I had that same fear, that he was always going to have some open gaping wound. It's normal to be worried!

Probably yes, and it's really not as bad as it sounds, I promise. Ziggy had the EXACT same  thing happen - I have some kinda gross pictures if you'd like to see them, I have no idea if you're squeamish or if that would help you to see another cat with it!

Like (I think) most amputations, Ziggy initially had one straight incision along where his back leg used to be. He had an area on the "outside" of the incision as well as a fairly large patch on the "inside" of it go necrotic. We didn't even know this was possible until I was gently wiping him trying to clean up some of the crust, and the thin, dead skin covering the inside portion wiped away and revealed a big icky pocket of dead tissue and pus underneath. We FREAKED OUT, of course, and rushed him to the vet. She said sometimes this happens and there's no way to know initially if it will. Sometimes the body just decides it doesn't need an area of skin, or it doesn't quite get enough blood or it's a little pinched by the sutures and it dies off. It doesn't happen in every case but she also told us it wasn't exactly uncommon and certainly didn't concern her in the sense of it being a huge weird deal, you know? 

What she ended up doing was what she called a "revision" to the incision. Instead of the straight line, it ended up Y shaped, with the top arms of the Y pointed towards his butt. Since it was a rear amputation, she gave him a little bit of a tummy tuck, pulling his belly skin up to make the new incision once she'd cut away the dead tissue and cleaned things up. Lots of stitches and staples to keep everything closed up and he went back on the oncior for a while - I can't remember if we were out of buprenorphine by that time. For us, the toughest part was having to put him back in a cone - without making this any longer than it already is, Ziggy had a very particular talent for escaping the cone. Unfortunately it basically reset the counter on the timer for the stitch and staple removal, so we ended up with those for a month rather than two weeks.

He did MUCH better once all of that was gone! It also seemed a lot better the second time, I think, because there wasn't so much trauma-related swelling after the surgery. Instead of being deep in the muscle and everything it was kind of a cosmetic issue, if that makes sense? Just at the surface of the skin instead of having to get down into muscle and tendons and all. Like I said, I have a TON of progress pictures and a couple from when his necrotic tissue was going if you want to compare it to Kaju.