We have had our chocolate lab since he was almost 10 weeks, now 17 weeks old.
We used a collar which was reflective and as it was too big when first used the reflective side was in contact with his neck hair.
There is white hair from the roots around his neck, a bigger patch at the back of his neck, he did not have any white hair when we first got him, we noticed a small amount of white hair then before we knew there was quite a bit. Our vet has not seen anything like this, no flea collar or chemicals have been used on the dog, collar taken off when bathed. The breeders who have both parents are also puzzled.
A spokesperson for the company who import/sell the collars suggested it was a natural flaw in the dogs coat. They also have not heard of loss of hair colour caused by these collars.
Of course if he was a golden we wouldn't have noticed.
I have attached a photo.
Does anyone have any ideas?