rats excessive thirst and urination

Question
A young male rat is drinking at least twice as much as the other boys. He also urinates constantly when out of his cage.  He is in a cage alone and his litter becomes soiled very quickly and has a strong urine odor.  He has been taking doxycycline for an uri.  He is fed Harland lab blocks and eats 2 - 3 dried cranberries a day.  
Do you have any idea what might cause this or what might help?  
Thank you for any help you can offer.

Answer

Doxy wont help a urinary tract infection like it would a respiratory infection.
He needs to be put on another antibiotic for a urinary tract infection.


I prefer Trimethoprim Sulfa, also known as Tribrissen or Co-trimoxazole. This is a very good drug for urinary tract infections and secondary infections as well.