Most places just use a CT scan to plot the tumour. MRI only if nothing seen on CT, which is a small percent. When I went to CSU they even had one case where tumour didn't show on CT or MRT but they did radiation anyway because there were a lot of acro symptoms. They just radiated the entire pituitary gland. Which is tiny.
Depends on your definition of success. We've seen maybe half dozen cats go off of insulin, but more important, most see reduction in dose and better QOL. Does the vet have experience with cats on cabergoline, or is he just quoting from the small study (5 cats) by the Royal Vet Clinic which is unfortunately getting too many views? The South America study had much better results numbers and much larger number of cats in their study.
Sorry, but more reading:
Quality of life and response to treatmentin cats with hypersomatotropism:the owners’ point of view This paper suggests that people giving cabergoline were pretty happy with it. Travel and cost are real factors for surgery and radiation therapy. One of the researchers posted here collecting survey responses.
If the vet is using modern protocols for diabetic cats undergoing anesthesia, they can eat until early morning, and have about 1/3 of their breakfast and 1/2 dose of insulin. More details in the second post here:
Info on Dental Procedures (including pictures) It's about dentals, but the second post is about anesthesia in general. If kitty gets high numbers, the clinic should be monitoring blood sugars, and can give a bit of R (Regular) or fast acting insulin to bring down the numbers.