dog shedding & diet

Question
My Corgi/Parsons Terrier mix (female) sheds all the time.  We feed her dry
dog food from the supermarket...popular brand.  We added some "high
protein" food, about 1/4 by volume, about 4 months ago.  There was no
change.  Please recommend a type of food (by composition) or a vitamin mix
(perhaps?) that might help.  *She also scratches herself alot (vigorously,
several times every day) but does not show evidence of irritation of the skin
nor evidence of bites.  She sometimes licks or bites at her lower legs.  I've
taken her to the vet, and she is protected by a tick & flea monthly application.  
A year ago, we tried a 6 day taper of Prednisone, but there was no
improvement at all.

Answer
http://www.freewebs.com/dustycovens/dietfeedingfoods.htm

my website address please see that page. I reccomend High quaility high protine low corn to No corn dog food for terriers in paticular with a great quaility food you will not have skin and coat problems as you are experiancing now. Also The two mixes mentioned both shed year round.