skin allergy in golden

Question
I have a female golden retriever age 10. We live in the same area since we've had her. Overnight she started with itching, biting her skin till it will bleed, redness on belly area inside of ears with abrasions, elbows,and knee areas. She will scratch, lick, and gnaw non stop. We've seen the vet twice and had a round of prednisone,and antiobiotics, plus some type of injection in the office to no avail. She is on benedryl 50mg bid with some relief. Tonight we noticed that while she is still and maybe sleeping her breathing is altered and there is some jerking in her legs. Can allergies develop overnight to this extreme, what type of allergy might it be, is the jerking and breathing a side effect of the benedryl? We live in Dallas and will be seeing a specialist on Monday at a referral clinic. We just lost our Choc. Lab to osteo sarcoma and we really hope this is not that type of news. The vet mentioned a dermatitis that is fatal called dermatitis lymphoma. Thanks for any help or advice. Su

Answer
If there has been no effect to the steroids, then I would have to think first of sarcoptic mange.  Has the dog been dipped for this parasite or has the vet given a shot for mange mites?  Benadryl will probably not be of much use as this drug has been shown to have no effect on dog allergies.  It will make the dog sleep and become lethargic. It is only useful for immediate hypersensitivities, like a bee sting.

Seeing a dermatologist is wise.