Rats can be very ferocious at times. My feelings about rats are that they are treated very cruelly and killed because sometimes they are considered pests. I know when I say this most people will agree with me. There are the kinds of rats that need to be exterminated like non-domestic, disease caring rats, and rats that bite for no considerable reason.
Domestic rats are also very prone to tumors.
My rat Lucy that I told you about died last year from a tumor. Her tumor got to the point where she couldn't walk or turn around to scratch her back. By the time we did that her tumor was about 2 inches in diameter, the size of a Tangerine. Rats can also have respiratory problems. Rats may live up to the age of 3-4 years.