Rats bite when they are frightened, under stress or want to be left alone. Unaltered male rats can sometimes bite out of aggression, and female rats that are pregnant or nursing a litter may bite to protect themselves or their babies. Rats sometimes bite when they are looking for a treat.
It’s important to teach your rat not to bite you. If your rat has not been spayed or neutered, have this surgery done first. Getting rid of sexual hormones may solve the problem.
Be careful not to reward your rat for biting you by giving it food if it nips, or by putting the rat back in the cage afterward. Instead, think about what may be motivating your rat’s behavior and try to remedy the situation. If your rat is frightened or stressed, remove whatever is scaring it. If your rat is biting because it’s distrustful of humans, you may need to handle your small pet more to get it used to people.