How long have you had your hamster? What kind of hamster is it and is it alone in it's cage? If you have only had your hamster for a short while, you may have purchased a female hamster that is pregnant. If this is the case, make sure that the cage is clean and she has fresh bedding so she can make a nest. Also make sure that there is plenty of good hamster food and fresh water, preferably from a bottle. If the hamster has babies, then do not touch the babies or disturb the cage for at least 12 to 14 days.
If you have had your hamster a long time and it lives alone, or it is a boy, then your hamster might have a tumour. If you find that your hamster is sensitive when you touch her or his stomach then be careful as she might bite if it hurts. She does not mean to bite, but this is her only defense against pain.
