My Rat Harpo

Question
Hi on August 8th 2007 i purchased 2 rex rats from a pets mart and i have had them a little over a year now. They are 2 males named Harpo and Groucho.  Harpo has always been a smaller then Groucho. But about about a week a go i discovered that Harpo was loosing wieght and breathing heavier than normal.  He was not eating as much and I didnt know if Groucho was just getting to it first but one night after letting the rats play in my room i decided to put Harpo in the cage before i put Groucho in, to see if he would eat.  He ate a little but not like he did before i noticed in decline in wieght.  He has not seemed real sluggish to me but not as much energy of he used to have.  They were still pretty young when we purchased them.  Sometimes during the night he makes sounds that make he sound like he has a stopped up nose.  My mother told me about how cancer is common in rats and i got a little worried.  I really need help on this because i love my rats and i dont know what i would do without them.  People from where i come from dont understand why i care for creatures like rats. I look at it this way if i dont give them a home who will.  These two little guys have been a big part of my life and i would like them to stay in it. So what does this sound like to you is it cancer, respitory infection ect?????
Please write back ASAP.  Not just for me for Harpo
  Thank you, Rat Girl

Answer
My first guess would be perhaps an upper respiratory infection - however have you taken him to see a vet? Cancer is in fact rampant in pet rats but take things one step at a time and have a wellness check done.

I'm sorry for my delay in answering.. The holiday rush caught up with me!

Good luck with Harpo.