I can understand your worries about Mika
. I had a Scottish Terrier that had many UTIs. She had many other health issues too. This was a tough little dog that didn't give signs of being sick--characteristic of the breed known as the "Diehard". Our internal medicine vet did several of the sterile urine draws straight from the bladder. I was not in the room when these were done, but my little dog did not seem to suffer any ill effects. The worst part were the ultrasounds. She had to have her tummy shaved and about a week afterwards she got very itchy as the hair began to grow back.
It was discovered that my dog had a polyp in her bladder and did need bladder surgery. Bladder cancer actually runs very high in my breed, but is a relatively uncommon cancer for most dogs. Please know that--I don't want to add to your worries. The sterile draw is actually very important. The sterile sample will allow the vet to culture the urine and find out the appropriate antibiotic for the infection. My little dog's infection (completely asymptomatic) was so severe she was on a 3 month antibiotic course before she could have surgery.