Sudden death of pet rats

Question
Hi,
My son had two female rats that were approximately six months old. We got them at the same time from the same litter. They were acting normal, healthy and playful all week. Yesterday when we woke up both rats were dead. They appeared to have died while sleeping together. They were not sneezing,coughing or acting lethargic.
They had been using aspen bedding. I had been feeding them kaytee's rat pellets. Nothing in their environment had changed. We gave them a few yogurt treats each day. I am at a complete loss as to what happened. Any ideas you have as to what might have caused this would be helpful. I am scared to get my son another pair of rats until we figure out what we did wrong.

Thanks!

Answer
Oh that is really unfortunate to read...losing both rats at the same time.  I wish I could pinpoint what happened but it would not be fair to say without a necropsy on both rats. To say they could have both had some type of congenital defect (where did you buy the rats from, pet store or private breeder?) is possible but kind of odd that they both died the same time.  This makes me wonder if they did not die from something in the environment that they could have gotten into....which you said was doubtful.  No pesticides at all have been used in your home that you know of or do you have a professional company come to your house to take care of any pests or rodents using sprays etc??  That is the only thing that comes to mind....some type of poisoning, which again is only a guess at this point.  Usually sudden death in an other wise happy healthy rat is from heart attack or a brain aneurysm but both at the same time? That is just strange.....strange, but not impossible, just not really probable, if that makes sense.