We first met Mr. Puss here: http://www.iwillhelpyourcat.com/dr-kris-qa/#/drkris-skinnyback/
This will seem overwhelming. It’s like driving automatic all your life, then you gotta drive stick shift. With manual steering. Up steep hills in traffic. Just like my Mazda 323 in 1997. Clutch down, then gas, clutch up...you jump start, then stall, then squeal the tires, then stall….and then one day you can do it all without thinking, and it’s a ballet of coordination.
This is what it’s like to treat a pet, who is losing weight and showing signs of kidney issues a la chronic kidney disease (CKD). It will seem uncoordinated and all over the place at first...but just give it time, and you’ll balance it all.
So - If we want to make that 15% kidney function as strong as can be (for some cat’s a well managed 15% can last a lifetime), then you want to customize to their kidney needs as much as possible. That means, the old approach of switch the food and throw in an ace inhibitor ain't for you. Here is the goal: make that remaining 15% remaining kidney as strong as possible. Make that 15% do push ups, and get so strong that it can support him instead of harm him.
How? Your vet did great by starting with those antibiotics. For all we know, infection could have reached the kidney, and we’ve got to get rid of that first. That urine was dilute, and bacterial love that).
Then you get into the technical overload stuff. This is the crunching of gears as you learn to drive stick. Not intuitive. It’s a grind. But it’s also the thing a great vet support team will sort out for you. You want to know:
That they are not anemic, and that their blood calcium, phosphorus and potassium is ok (i.e that the rest of the bloodwork is ok - if not, find out and fix)
The urine UPC (it might have been high for Mr. Puss - he is on fortekor - a medication to reduce that). The infection can influence this so it's worthwhile to recheck this after the antibiotics.
What is their blood pressure?
Make sure there is no kidney stones in there (i.e. Xray is a good idea).
Make sure there is no sub-clinical hyperthyroidism or active hyperthyroidism.
With all that info at hand, I’m going to simplify and customize what this little guy would need in terms of food, supplements, requirements for SQ fluids, medications etc. Can’t get all that info? Well then just do the best that you can. I listed them in order or importance (for most cats...but they are all different).
It might sound overwhelming at first. But it’s all designed to remove the guesswork, and get down to the core requirements his kidneys are asking for. But once you know their specific requirements, you know what to focus on, and things get smooth.
Typical first goals? Tweak what you need to so he eats. The weight loss needs to either stop or be lessened. It could be antacids. He may really benifit from SQ fluids as explained in this post (http://www.iwillhelpyourcat.com/videos/#/give-sq-fluids-like-a-pro-and-save-your-cat/). I highly encourage that. He might need miralax added to his food to help him with the constipation. Maybe he needs mirtazapine. Maybe he needs super irresistible food (with supplements added to the food to correct for his needs if his phosphorous is to high) to get him jump started. There are plenty of renal/kidney speciality foods out there, but your cat doesn't care. He cares about palatability, odour, texture and taste. Fix that first to get him eating. The kidney foods have a place, but they are a long term strategy for some cats. All CKD cats are different. If they eat them right off the bat, then great. If they don’t, move on to the next thing and revisit the kidney food later. Nothing wrong with doing that.
That’s how you start. Let us know how your first launch into protecting that 15% goes. There is more that can be done even still...