what is making my sisters dog itch so much?

Question
QUESTION: Hi, my sister has a golden retreiver/german shepard mix; I don't know how old the dog is.  But since November last year the dog has been scratching and using her teeth to scratch itches so it looks like she is biting herself.  She has been checked for fleas and she had a few so my sister bought a tick and flea collar and flea treatment in hopes that the dog would stop scratching but she just keeps scratching, using her teeth, and constantly cleaning herself (it seems more that a dog would normally do).  My sister switched the dog's shampoo from an oatmeal based shampoo to one that specializes in dandruff or something in hopes that would work and at first it made her clean herself more and then she started the scratching and all that again.  What could possibly be causing her to itch so much?

ANSWER: Flea allergy dermatitis is a possibility as are other types of allergic skin disease. Your vet can try some steroid therapy to see if it relieves the itching.  Also a good flea medicine or topical may be needed. Many dogs with skin allergies also have a secondary bacterial or yeast infection that cause itch must be treated.

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

QUESTION: I told my sister what you said in your answer and she has a few follow-up questions to have me ask you.  She would like to know that if the dog would have flea allergy dermatitis would the dog have any sores?  Also last summer she had a huge infestation of bees around the house and the dog was stung over twenty times because there was so many bees outside.  So my sister would like to know if being stung by so many bees could ause something like that.  Oh and she would also like to know if the dog could have flea allergy dermatitis if the dog has no fleas?

Answer
Sores are made from the dog self traumatizing the skin.  The intense itching causes many dogs to mutilate themselves.  We can have a flea allergy show up in dogs with as few as one flea present every 45 days.  The flea saliva binds to the collagen in the skin when the flea feeds and it is slowly released.  That is why many dogs without live fleas on them have all of the signs of flea allergy on their skin.