They don't live very long. They get respiratory I infections and are predisposed to get cancer. I used to have rats several years ago. I took them to the vet when they were sick. I could tell you rat stories until the su n comes up.
I used Loop 494 when I had them. Dr Dori does Exotics. She was reasonable. If they had surgery to have tumors removed, it was under $100. When they got sick, the office visit was like $26 plus liquid Baytril for upper respiratory infection was not near as expensive as the Baytril tablets for dogs or cats. She n I had to put them to sleep, Dr Dori put them to sleep for around $26.. All my rats either died from cancer or upper respiratory. They will almost all get cancer. Very important to use Care Fresh bedding, and give them fresh fruits & veggies along with a good diet formulated for rats.