I really don't think that what you need is a second opinion!! The treatment that your husband is getting is exactly what should be recommended for his condition. It is not uncommon for a treatment to be delayed because of low blood counts; the chemo agents used ARE toxic, which is how they kill cancer cells. If a patient's blood counts drop, it would be malpractice to give more chemo until they have had a chance to rebound. This often happens, and, when they have recovered, the treatments will continue. Others may chime in here, but I know that there are several people on this Forum who have done this, had to wait because of low blood counts, and then continued successfully.
Having said that I didn't think you needed a second opinion, I think you do need to get some communication going with his doctors. (Hint: I often find that by called the doctor's nurse I can get either really good information OR a call back from the doctor.) Don't be afraid to ask LOTS of questions and to be a bit assertive!
You are at one of the best places for bladder cancer treatment. Also, I doubt that another site such as Mayo would consider taking him for treatment until this series is completed. However, don't ever think that you shouldn't ask questions or (politely) note complaints because the doctors "might be upset." You are the customer here!!!
Please find someone...doctor, nurse, clinic administrator...who can answer your questions.
And best of luck to you both.
Sara Anne