Rat is eating sand??

Question
QUESTION: My rat is approaching 2 years and is slowing down drastically. A little while ago she seemed to have started slowing down eating and has grown thinner and there is a lot less faeces present in the cage than before. In her cage she has a small sand box that I've noticed becoming less empty over the past few days and it would appear that she is actually eating the sand?? She wont eat her regular food either and is even very slow to eat any treats (pretzels) that she receives...
Is there something wrong that can be fixed? Is she sick? Would removing the sand make her more interested in her other food? Is it just age taking its toll?

ANSWER: why is there sand in the cage with the rat in the first place?

What is her diet?  Also, you should not feed her pretzels as treats, as there is too much sodium in them for rats to handle. Their kidneys are very fragile and should be on a low protein, low fat diet. Sand is very bad for rats as this can irritate the delicate lung tissue and cause problems with their breathing later in life.  As for age taking its toll, I am more worried that having sand in her cage is what could be causing health problems.  Weight loss is a sign of kidney disease and heart disease which is why I asked about her diet.
With a few changes, hopefully we can get her on the right track and she can live to be a nice old grandma rattie!

---------- FOLLOW-UP ----------

QUESTION: Thank you for your reply!
I have removed the sand box from her cage - I read on a website soon after I got her that you could train a rat to use a sand box similar to a cat, and so she has had a small sand box in her cage for most of her life. It is gone now.
Her regular diet consisted of a rodent mix from the pet store which included sunflower seeds, pellets(similar to rabbit food), wheat, coloured balls that appear like dog pellets, and dry corn. Of that she doesn't touch the wheat or pellets.
Since I noticed her conditions I swapped her food for some oats with fruit bits in them, and have also started picking fresh basil and lettuce from the garden which she seems to eat all of. I also haven't been giving her pretzels since I noticed her conditions.
Yesterday while eating her greens though, she appeared to start wheezing a bit, or gagging, I'm not entirely sure what - but it was as if she had hiccups. Only after a good 30 - 45 minutes it died down. It was the first time I had seen her do that.
What should be done?
Thank you so much for your help! It is truly appreciated!!

Answer
It sounds like she may have been coughing.  Do you hear a sound when she breathes?   Do you have a vet that sees rats in your area?

Check out my website on rat diets...there are alot of ideas of things she can eat rather than just the sunflower seeds from her food mix, which isnt very wholesome.   I think you will get alot of good ideas about what you can feed her to keep her healthy too.  I think she needs medication though, because she may have a respiratory infection.

Here is the URL to my site. Let me know what you think, please!

http://www.freewebs.com/crittercity/ratsandahealthydiet.htm