My dog wont stop itching!

Question
Hello, I have an 8 year old 30 pound mixed breed (terrier type) female dog.  She has a severe itching/scratching problem.  We have gone through the basic regimen of creams, then shots, and now she is on Atopica.  The Atopica works fairly well, as the creams and shots didn't work at all, but it hasn't worked great.  She has to take the 100mg size pill, as the 50mg doesn't help much.  This is obviously a very expensive pill, and like I mentioned, it works good, not great.  My question is if it could be something in our house, such as allergies in the air, dust, etc. We moved into a new house in a new town about 2 years ago.  The itching started about 6 months after we moved in.  She will lick and lick until her paws and stomach are raw and red.  We probably don't vaccuum the house as much as we should (maybe once a week) and we don't have an air purifier.  Is it possible that this could be our problem?  Can you recommend a good air purifier for pets?  Or should the 100mg Atopica knock out any allergy problems, and it is something else?  Is there a simple household test to see what it could be?  Thank you for your help.
Todd Hartz  

Answer
Your dog does have allergies.  The only way to know just what she is allergic to is to have her allergy tested.  If you do that, then you really need to consider hyposensitizing her to the specific allergens that she is sensitive to.  Ask your vet about allergy testing.

Atopica is fine for helping remove the itching, but if you don't take care of the allergies, when you stop the Atopica, the itching will return.

Another thing that works well is to add Omega3 fatty acids in her food to make the skin less sensitive to allergens that get on the skin.  Ask your vet which supplement is recommended.  It takes 30-60 days for these dietary oils to begin to work, so don't get discouraged.