Hello I am Dr. Joey. Thanks for trusting me to help you and your pet today. I am a licensed veterinarian with over 16 years of experience. I look forward to working with you.
This poor girl. My top worries when we identify a suspected UTI and the symptoms do not seem to be abating is either the bacteria causing the infection is resistant to the chosen antibiotic or this is not a UTI. If not a UTI then the top concerns would be bladder tumor (best seen via ultrasound) or idiopathic cystitis (sterile inflammation of the bladder).
After 48-72 hours on the antibiotic, we should see tremendous improvement and not a back slide such as this. Therefore, if Peanut was my patient I would recommend a recheck to do 1) ultrasound of the urinary system that included both kidneys and urinary bladder and 2)urine culture (if nothing seen on the ultrasound). Now a culture can be complicated by the fact she is on an antibiotic. I mean, it can lead to a false negative because the high concentration of the antibiotic in urine sitting in-wait on its way to the lab can sometimes kill a bacteria, even if resistant. But it is still a worthwhile test.
If there is any evidence of bleeding or anemia on a recheck exam anywhere else (weakness, pale gums, new heart murmur, etc), then updating some lab work to ensure there is not a bleeding issue going on is also an important step.
I am at a point I need to know what questions you have. I hope that the information I provided has been helpful.
Please let me know if for any reason you need further clarification, have more questions, or were expecting a different type of answer.
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