Thanks for your reply.
There are several causes for acute kidney failure, including toxicities (certain chemicals or medications), certain infections (Leptospirosis is one example), lack of oxygen to the kidneys, trauma, to name a few. Further testing may be needed to try and find an exact cause (i.e. ultrasound of the kidneys, Leptospirosis blood titers).
I would certainly continue treatment with IV fluids, antinausea medication as needed, antibiotics, and rechecking bloodwork at least every 24 hours. Some dogs will improve within 24 hours of starting treatment, while others can take several days. So, don't give up yet. If you are treating Sammy for a few days, and there is no improvement in his condition, or if the kidney values are not improving (or if they're getting worse), then you may need to discuss having kidney dialysis performed (likely at a specialty clinic or veterinary school), or euthanasia. Euthanasia is very difficult to even think of, but if after treating a few days, and his condition is not improving, then it may be an option to prevent suffering. I don't take this lightly, that is why I would not be doing that yet, I would give Sammy more time, since many dogs take longer than a day or two to improve.
You can read a good article on acute renal failure in dogs HERE. It is a few pages long.
I hope this helps. Please let me know if I can assist you further.