dogs skin

Question
I have a Golden Retriever and she has had a rash or irritation since we have owned her since a puppy (8 or 9 years now).  I have taken her to many vets and they have no idea and tell me not to worry about it.  My husband had a golden growing up and the dog had these same spots on his face and they thought it was an allergic reaction to grass and was told our dog had the same thing. I thought that since you do dog grooming you might be familiar with this.  It is only on her back paw and she bites it a lot.  The paw has always been swollen from this and has bald spots.  I can't seem to find a real picture of red mange (all I can find are hand drawn).  Do you have a picture of localized red mange?  I am taking her to the vet tomorrow because today my husband threw the ball for her and she started limping and not putting any weight on this paw.  She usually limps a little bit after ball but this is really bad.  I checked her for thorns or to see if it hurt and she didn't seem to mind me touching and massaging her.  Recently we put bug killer and weed and feed on the lawn and I know this effects animals.  Any suggestions or pictures would be appreciated.

Answer
First of all, that stuff you are putting on your lawn is highly toxic to animals and people. Do not let her on it, but only exercise her in an area that has not been treated.

As to the mange, here are some sites with photos: http://www.thepetcenter.com/exa/mites.html
http://www.petplace.com/dogs/demodicosis-red-mange-in-dogs/page1.aspx
http://www.peteducation.com/article.cfm?cls=2&articleid=729