Stomatitis is inflammation of the gums and periodontal regions. This is frequently triggered in older cats when they have a few cavities. Here is a little more information about stomatitis:
In my experience, stomatitis is recurring and chronic. Cleaning is the first step, with removal of teeth that have cavities. More often than not, in my experience, we end up removing all of the teeth in order to establish complete resolution and comfort.
Two things I would make sure you have discussed with your veterinarian:
IV fluid therapy and monitoring of blood pressure when he is under anesthesia. In older kitties, low blood pressure is common when they are under anesthesia. If this pressure is too low for too long, it can have negative long term affects on the kidneys. IV fluids helps to minimize this risk, and monitoring blood pressure ensures that if the pressures are low, we do something about it quickly!
Pain medications! I like how you think! There are a couple of options for pain in kitties:
NSAIDs - non-steroidal anti -inflammatories. The one used in cats most often is Metacam. I have been known to use this, but would be hesitant in an older cat.
Buprenorphine or Buprinex might be the best bet for him. It can be given 3-4 times daily by just placing it in the cheek. It is absorbed well across the mucous membranes.
Fentanyl patches. Some veterinarians are comfortable with these, some are not. My comfort depends on the household setting. If there are kids who are too young to understand the danger, or other animals who might ingest the patch from off of the cat, I would be hesitant to use them. In households where kids and or adults are able to watch things and there aren't other animals that we worry about, I think patches are a great option!
I think it is wise to sit down and discuss all of these concerns with your veterinarian before going ahead with the procedure, to make sure you are on the same page.
I hope this helps!
As always, if you have follow up questions, please don't hesitate to ask them using the "reply" function.