hair loss

Question
Hi, I have a 12 week old black toy poodle puppy. She has quite severe hair loss on her back (above her hindlegs) and half way up the tail. It looks as though she has dandruff where the hair has fallen out however I have been to the vets and they have said it is not fleas or mites. They advised me to contact the breeder to see if there was any hair loss with any other puppies in the litter but there was not. She is not scratching excessively and is behaving as her normal happy self. I do not know if this is worth mentioning but the patches where the hair has fallen out, there is a small layer of grey/white hair as there is through all her coat, so it is not quite patches of bare skin?? Although her skin is white and she does have stray white hairs around the nose and under her paws. I am taking her for a skin biopsy tomorrow but in the meantime do you have any idea what this could be?? thanks

Answer
Hello Bryony,
It very well could be that your dog has some kind of allergy to something in his enviroment.  You might talk to your Vet and see if he/she thinks this could be a possiblity, and if so, mention giving your dog Benedryl for a week or so to see if this helps any.  

It could also be a hot spot and hot spots can be caused by a number of things.  Stress can cause them, allergic reactions, being exposed to chemicals (such as cleaning products, laundry soaps, neighbors spraying their grass and your dog being exposed, etc) food allergies, or illness.  

About her hair color at her skin, are you for sure she is a true Black?  Could she be a Blue or Silver?  If she has Silver or Blue in her background, she could be starting to turn.  
Blue colored puppies are born Black, but usually have a tinge of Brown at the tips of their hair.  This is a good indicator that the puppy will be a Blue rather than a Black.  
Some solid colored dogs are born with white colored feet or with white on the chest, but this usually fades.
Also, you can find dogs with white hairs throughout their coat, if they are a Black dog that has a white parent in its backgroung.  These dogs aren't True Black because they have the Fading gene from the White dog and will eventually fade as they age; or at least get more of the white hairs scattered throughout the body.  

I hope this helps you some.  If you have other questions for me, please feel free to ask.

Thanks for using AllExperts.com,
Kim