Dog bleeding from penis

Question
Hello, I have an American Pit Bull, three years old, and yesterday, I noticed that he was bleeding from the penis. I have not noticed him having any discomfort while urinating, nor any thing else for that matter, except that he may be drinking much less water. I took him to the vet (he's 65 lbs., by the way), who took a urine sample, and felt his prostate. He perscribed two weeks of antibiotics, and told me to follow up a week after that. If it has not cleared up by then, then we will need another urine sample, and some x-rays, for it may be cancer. My question is, what on earth could it be, and might it just be that dreaded cancer? Thank-you for your time. The Paul

Answer
He could very well just have a bladder or prostate infection.  If the bleeding persists, blood work should be done to check his white, red and platelet counts as well as kidney/liver function.  He could also have bladder stones that are causing the bleeding, which will be evident on an x-ray.  At three I would not suspect bladder or prostate cancer, however, it always has to be on the list if he is not getting better.