They seem to believe there is a mass (by feeling?) but only took Xrays. And with this guess they suggested putting the dog to sleep? It's good that they referred you to a specialist.

You should expect the specialist at a very minimum to perform an ultrasound, and to send a urine sample sent off to pathology. Until that is performed there is still a possibility of an infection with a benign mass wrapped around the bladder.

If it turns out to be TCC most likely you would want to try to find a Vet oncologist. The first big question would be if there was evidence of wide metastasis? Ultrasound will answer this question. Currently the treatment of choice for TCC is Mitoxantrone plus piroxicam. An older treatment was with Cisplatin which has not been too effective. Also Cisplatin is a nasty per nausea. If there is widespread metastasis ask the specialist/oncologist about the possibility of Doxorubicin plus Cytoxin, at least to begin with.

Let's assume that the diagnosis is TCC, and the Vet involved suggests Mitoxantrone plus piroxicam. What should you expect? First Mitoxantrone is one of the more expensive Chemo drugs or at least was 3 yrs ago. Mitoxantrone was created in the hope that it would be as effective as Doxorubicin without as high rate of cardiotoxicity as Doxorubicin. For the most part it's less effective than Doxorubicin for many cancers, but is less cardiotoxic. In general its side effect profile is simular to Doxorubicin per potential for nausea 48-72 hrs post administration. This can be suppressed with metoclopromide (10 mg 3X daily) during this period of time. Also acid blockers such as cimetidine or rantidine will not only help suppress any Chemo nausea, but should be given to decrease the irritation that the Cox-2 like piroxicam will create in the stomach. Ulcers could easily develop with the piroxicam if acid blockers are not used.

The response rate for TCC to Mitoxantrone plus Piroxicam is 35-75% with a median survival time of 350 days. If you are able to get your puppy dog into a remission even a partial one, then during the remission period it will enjoy a high quality of life. Most cancer puppies given Chemo will go down hill extremely quickly and succumb to a bacterial infection at the end.

Try a chemo therapy, and see if it helps.