Missing Hamster

i've only had my hamster for three weeks and this is my first one. she went missing 3 days ago and i cant find her anywhere!i really need advise because my mom keeps vaccuuming up all her food that i left out and i hav a 15 year old dog.will he hurt it?he's pretty nice. we also think that he might have gone down stairs. please leave some tips!!!

Question From: keili bartlett - Jul 25th 2007