My rat terrier, Randy, hasn't been himself for the past month or so. He never has accidents in the house but for the past few weeks he has had several. It seems that he just can't hold his urine. He can usually go hours between having to go to the bathroom but now its like he has to go much more often and sometimes its like he just can't hold it anymore and either pees a huge puddle or is leaking it out. Last week, Randy woke up shaking terribly and just laying around. He walked reallly slow and seemed like he was in pain. He peed very often and just wasn't himself. I took him to the doctor. They tested for kidney disease and cushing's disease but those tests came back normal. They also have ruled out urinary and bladder infections. They want to do another urine test to see if his kidneys concentrate his urine. I don't know what that means. Is it also possible that he could have a kidney stone? I'm not sure what is going on. Any ideas?