Hi, unfortunately I do have this problem with my Jasper. I need to have his expressed every 4-8 weeks. fiber does help. And it is easier if the food you feed has at least 4-5%
I have heard, unless they get infected or impacted all the time-- it is best not to do the surgery as it can lead to incontinence. I've been told, The best route is to have them routinely expressed. But I would be really curious if your vet reccommends the surgery-- perhaps there are new procedures that have fewer side effects.
One thing, that has helped us is a supplement cailed arabinogalatin powder. It is a prebiotic fiber, but it also has is a powerful autoimmune support. I am not sure what the dose would be for a puppy... You have to mess with the dose-- too much can make it worse. we were told to start with 1/4 tsp twice a day and go from there. Jasper now gets 1/8th tsp once or twice a day. It has allowed us to 6 -8 weeks most of the time.
My vet suspects allergies as a possible cause, and a raw diet (with extra fiber) has helped... but also Jasper's AG's are misplaced...so all the fiber in the world doesn't help poor Jasper. His need to be expressed from the inside, if done right, by my vet with magic fingers it lasts a really long time, whenever it is done by a vet tech I am back in 4 weeks.
good luck. I would really do research before doing the surgery. But I would love to hear what you find out.