Originally Posted by Pavel
Any idea how it's possible do not kill bacteria with so strong medication during 1 month? (He also get small dose of methimazole because thyroid desease).
How is the urine sample being acquired and tested? Is it via cystocentisis (ie: a needle into the bladder)? Is the urine being sent out to a lab for a culture and sensitivity? That would help determine which antibiotic would be most effective against the particular type of bacteria you're dealing with.
Do you know how well controlled his hyperthyroidism is? I ask because if he's still drinking and peeing more than normal, his urine is probably rather dilute and is a more hospitable environment for bacteria to grow. When was the last time he had his T4 levels checked?