Italian Greyhound hair loss

Question
I have a 3.5 year old female IG named Izzy who has been experiencing hair loss.  When she was around 2 years old her muzzle started turning white and the sort of coarse hair on her back started thinning.  When I took her to a Vet. check up they ran a battery of tests including ones for fungal and insects.  Recently I took her to another Vet. and they ran some more tests including kidney, liver, and a thyroid test that they had to send out...everything came back as normal.  They said that it might just be a genetic thing or related to stress.  Any ideas or suggestions?  Thanks.

Answer
This is obviously a hair follicle problem.  The pigmentation is wrong in the follicles where the hair is turning white and the coarse hair is abnormal growth of the follicle.  TO be sure, your vet can do a biopsy of the abnormal hairs and let the pathologist decide the problem.