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.
My rats were housed in my spare room. I had 4 cages of them, all separated by sex (M/F). I bought 2 rats @ two different times, and they were preggo. Got them at Pets Mart. Talk about surprised. I kept all the babies, weaned them and separated them. They had a good life. I fed them like Kings & Queens.
I got a hairless rat as a class pet because I had done so much reading on how great they are with young kids. Had to get a hairless one because I had students with allergies. I totally fell in love with her. When I left the school I took her home with me. She did get cancer at about 2 1/2 years old. I had one surgery done on her to remove a couple tumors. She was awesome. We'd chill and watch tv, or I'd put her in her ball and let her chase my sister's dogs around. She'd swim around in the tub and I'd put olive oil on her so her skin didn't get dry. Haha! Her favorite thing in the world was to be fed baby food out of a syringe. Miss my Lucy! Kenny was totally grossed out by her, so I'd torture him and put her on his shoulder. Great way to make a grown man beg. LOL!