Urinary infection

I had both of my boys fixed three weeks ago. They are five years old now and were fighting terribly. The vets suggested the operation so I had it done. Last friday one of my boys was very listless and vomiting. He could not urinate. So he went back to the vet. They did blood work and xrays but couldnt find anything major wrong with him. they put tried twice to put in cathaters to expell urine and he chewed both of them out. they sent him home and we have been doing antibiotics all week. he seems better but he has swelling right at the base of his tail and he dosent seem to move it much. do you think it was just damaged or do you think more could be wrong......

I just noticed another ost about UTI and it said that one round of antiboitics sometimes dosent work. Will he get all sad and sick again of it returns ??

For most cats one round of antibiotics works wonders, but for others -- especially if the infection is really bad -- a second round of treatment is necessary.

With that said, your description of what happened to your cat sounds as if there is something more going on than a urinary tract infection. If I were you I would visit another vet to get a second opinion about what is going on.