Possible allergy

Question
I have 2 female rats about 1 year old, they are cage kept and we use Cell Sorb Plus for bedding, which I change once a week and clean cage.  They eat regular vita-pus mouse,rat & gerbil mix from the pet store and fresh fruit & veggies.  They are itching until they bleed with sores all over.   They have had 2 visits to vet so far no mites, or growths.  The vet felt that it was a food or an environmental allergic reaction to something and gave them steroid injections.  They clear up right away and then about 30 - 45 days later, they start creating sores again! Any ideas? are there any foods or household products that would cause this reaction.  We do not spray any chemicals in the carpet or use spray air fresheners anywhere near their cage, which is in the main family room open to kitchen. These vet trips are getting costly.

Answer
Hi Patti!!

I already believe I know the answer to this question!!
Its the rats diet and the food they are eating!!!
Commercial seed mixes are terribly high in protein which can contribute to the allergies and also later in life can cause problems with kidneys.
Rats should have no more than 15 protein in their diets.

My suggestion (and this should greatly reduce your trips to the vets!!) is to look into changing their diet.
You may need to use the internet to locate the foods I am about to suggest, starting with a rodent block made by HARLAN TEKLAD.  
You can order it online at the following URL:

http://www.kimsarkrescue.org/content/view/35

Also, some exotic vets carry REGAL RAT made by OXBOW, but a fast internet search should lead you to a source to purchase it if not. Its a great rat kibble. Actually they both are and have all they need to meet their nutritional requirements. I am surprised your vet didnt think of the diet first hand once parasites were ruled out.  
Commercial seeds are so full of fats and unwanted things, thats the first question we ask at the clinic: What diet do you feed your rats?!
Also, there are TONS of recipes made by fellow rat lovers that are floating around the net and I have a link on my website to a very reputable site that shares the ingredients.  Its pretty basic stuff actually, from mixing up unsweetened cereals such as rice chex, puffed rice and puffed wheat, dry oatmeal, dehydrated cranberries, uncooked crazy mac (the green and orange pasta that is spinach and carrots or tomato, I cant recall now, my rats arent wild about it! LOL)  and the list goes on.....this fed with a good rodent block or regal rat food OR dry dog food, which is low in protein: NUTRO LITE DOG FOOD.  
Here is the link to my website. Scroll down for diet tips and recipes and links for the recipes.
http://www.freewebs.com/crittercity/healthcare.htm

You should see a change within at least 14 days.

Hope this helps.