How will you know? I don't think anyone can tell you that. (For myself and my cat, I promised her that when she couldn't enjoy life, or lived in pain, fear that I would end it.) There's also the question of how much a person can take.
*I really don't understand why they haven't sent you home with sub q fluids! They aren't the answer for every case, but in the US, it is one of the very first things vets RX for kidney diagnosis.
They are NOT difficult to administer once someone walks you through it can you get confident in the process. I warmed the fluids in a sink of hot water and my cat would purr through the process.
As the BUN level goes up, the appetite goes down and digestive issues go up. Fluids flush the toxins from the blood, lowering the BUN levels (it won't fix the cause).
Again, I know that sub q fluids weren't legal in the UK a few years ago, and if they are now...then it's still a very new thing that probably hasn't caught on fully. (I did note that the vets at your clinic are all older doctors. I found the best kidney vets I found were younger...simply because med school was fresher, and their experience level had them seek consults with other vets.
But if you have the strength to fight a little longer, I'd start demanding more from these vets. (Don't I sound like a tough outspoken witch? Not at all, I'm shy and quiet mostly. But I almost euthanized my cat at diagnosis due to my fear of medical things, and the overwhelming process of learning how to live with her illness. I had good people help me through; and four more good years with her.) My goal is to help you handle as much as you're capable, and to not let you give up until you feel its needed. And I will always support what you need to do!
This is taken from
http://www.felinecrf.org/subcutaneous_fluids.htm and is a direct quote:
"Not only that, but dehydration feels horrible. Human CKD patients have described dehydration and the accompanying high levels of toxins in the blood as feeling similar to a bad hangover. It can make you feel so horrible that you stop eating and drinking, and according to
Evidence-based step-wise approach to managing chronic kidney disease in dogs and cats (2013) Polzin DJ
Journal of Veterinary Emergency Critical Care (San Antonio) 23(2) pp205-15, it may even "precipitate a uremic crisis" and "predispose to
AKI [acute kidney injury].""
Myself, not knowing all the details of Buster's condition....I'd want to see how the next 2 - 4 weeks go while using fluids at home.