I am sorry to hear you are worried about Rusty. I am a veterinarian, and will do my best to help.
Are they cysts, or could there be a bladder tumor?
Has an ultrasound of his bladder been done?
If this were my dog, I would have a urine specimen sent to the lab to see if there are abnormal cells in the urine. If that does not tell us what these cysts/growths
are, then I would next ultrasound the bladder and try to get a good look at these, and try to use a needle, guided by the ultrasound, to get a tiny biopsy of one of the cysts.
There is a medication called Piroxicam, and also a similar one called meloxicam, that can shrink bladder tumors
in some cases.
This could be something serious and if this were my own dog, I would get a diagnosis, and get a second opinion whether this is truly inoperable by talking to a surgery specialist. Once we get a diagnosis, once we know what we are dealing with, we know the best options for treatment.
Let me know what other questions I can answer.