Have Cat Questions? Ask a Cat Vet Online.
Hello, this is Dr. Jess. I am sorry to hear about your kitty! Unfortunately the only treatment for a urinary tract infection is an antibiotic and that is available by prescription only, which must be written by a vet who has examined your cat, so we cannot give you a prescription here online. If you do not feel comfortable with the vet you have previously seen, you may consider finding a different vet in your area, do you live somewhere another vet is available?
What area do you live in? One thing I will recommend to people is to look for an AAHA accredited hospital.
If you go on this website: https://www.aaha.org/pet_owner/about_aaha/hospital_search/ you can find an AAHA accredited hospital near you. AAHA (The American Animal Hospital Association) is a group that goes to veterinary hospitals and reviews their practices and protocols to be sure they are up to the standards of care in veterinary medicine, so hopefully they are practicing good medicine. You may also let the vet know when you meet them that you have left your old vet because you felt they weren't listening to your personal needs and explain to them what happened. That can let the new vet know your thoughts ahead of time and your cat's history.
I am sorry, I don't really have any experience in giving cranberry extract to cats, and so I do not have a dosage guideline to give you. I will open your question back up in case another expert can provide you with this information.