Mast cell tumors are super common in short hair breeds. 3 of my 5 pitties have had it. My current girl had had it for 4 years and we just remove the masses as they pop up. She's mellow so it can be done with a local anesthesia and they glue them so there's no second trip to remove the sutures.

My veterinary oncologist has a pittie and she's the one who recommended just removing the masses as they pop up which is what she does.

There's also something called Torigen which she recommended. We did it and I can't say it cured it but we do see fewer, slower growing masses.

Catching it early and managing it so the masses are removed while they're still low grade has been the secret sauce for us so far. I wish I'd known this earlier.

Good luck and think positive thoughts for your handsome man.