I have a great deal of experience with Kidney and Urinary Tract problems in dogs and have several articles on the subject describing what you can do yourself and what I can send to you to support your dogs recovery. Start treating with my Kidney Weakness Mix.
For your dog it would be advisable to start the course at 10 drops twice daily and continue at this rate for the first four weeks.
After you have introduced the herbs after 2 weeks you could stop the antibiotics altogether & also any commercial dog foods.
You would also be advised to start a convalescent diet consisting of only one meal a day and this to be raw chicken necks including the bones. We must unload the kidneys and to do this we need to get rid of all processed feed and all snacks so your dog's immunity and metabolism may be completely focused on healing and clearing toxins from the system.
I also recommend that you place your dog there after on a diet of raw meat & bones i.e. beef/mutton bones with meat on them or raw chicken necks and wings, mince, definitely no processed food and snacks. You can also add some freshly cooked vegetables and rice as well.
If your dog is not already on this type of diet, then I suggest that you introduce it slowly.
Have a read of the following articles regarding dogs diets and why it is important to keep it natural and simple.
Natural Feeding and Rearing Dogs with Healthy Bones