Glad he is on cisapride, that is the mainstay for this condition. Lactulose is a good call as well.
That surgery is not one routinely performed by general practice veterinarians. You'll want a specialist to that type of surgery, if he is a candidate. Given your interest in this at this time I'd suggest bringing it up with your current veterinarian, and request a referral to a surgeon that you could discuss it with. This is not without risks of complications, and you might decide you'd rather continue management.
Diet modification with added fiber could be considered. Stool softener could be considered. Lactulose dosage and/or frequency change could be considered. Enemas should be continued. Other promotility agents could be tried, such as metoclopramide, but cisapride really is the best for this condition, and unfortunately a lot of these cases are simply difficult to manage medically and take a lot of work on the owners part as you're experiencing.
Steroids wouldn't be the first thing I'd reach for here personally, unless I was suspecting a component of inflammatory bowel disease for example.
Risks of surgery increases with age. His overall health should be taken into account when considering a major surgery like what you're asking about. This will be part of the discussion. You also need to discuss long term complications of this surgery that will be anticipated, even if it goes well. Lot's of things to consider, and if you're seriously considering a surgery these are best all discussed with a board-certified surgeon to get their opinion.
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