Dana I'm sorry you and Bumble are dealing with so much. My yorkie is 15 and has been dealing with a trifecta of issues involving his liver, kidneys and pancreas for the past couple of years. He also initially had some gall bladder issues but Ursodial has helped, and I'm told that he will be on that medication for the rest of his life. I would also be very cautious of having even a needle guided biopsy done by a general practice vet. We have considered having a biopsy done a couple of different times, but when I asked our Internal Medicine vet what she expected/hoped to find and how it would change his treatment plan, she said the information would be good to have, but that he was already on the standard of care for his condition anyway. And a needle guided biopsy is iffy anyway, as they have to hit exactly the right spot in the liver to get any information at all. Our IM vet actually admitted that in more cases than not, the results come back inconclusive. So we passed on it.
Your vet does seem to be on the right path with trying to get Bumble stabilized. IV fluids are the best way to get the BUN and phosphorous down as they are both extremely high. A phosphorous level that high can cause a lot of damage to your dog's internal organs and a BUN of 169 means that his system is very acidic and could definitely cause an ulcer. Luckily the creatinine is holding very well at 2.5. Yes, it's elevated, but my Scooby's creatinine has jumped as high as 3.5 with a pancreas flare and we've always been able to get it back down to under 1.5 once the pancreas is under control. All medications come with risks and cautions and precautions, so it is important to weigh the risk vs benefit but both Carafate and Aluminum Hydroxide are very often prescribed for dogs with Phos and BUN that high. I'm not trying to indicate that your Bumble's issues are exactly the same as my Scooby, but many dogs do have this trifecta of issues, especially with the liver and kidneys. Sometimes the answers are elusive and you just have to treat systematically and manage the symptoms. As I said before, my little Scooby is 15 and has been dealing with these issues for about two years now. He has a pretty good life.
We manage his symptoms with denamarin, ursodial, metronidazole, Pepcid, various vitamins and supplements, a very strict diet with no fat, and he has been getting sub q fluids at home now for about a year. It takes five minutes out of my day and really improves his quality of life. He continues to have flare ups every several months but I have learned to recognize the symptoms and catch them early and he's usually back to normal in a day or two.
Hope today is the day your baby will begin to turn around and show some improvement.
Diana and Scooby